Hello All,
In December 2005 we spoke about this. There someone I know who has a critical ear and wants to listen to good sound from his AC/DC sets at low voume. He's annoyed by the half-wave hum.
In the discussion we concluded that if the power supply produces 110-125 volts DC, then the tubes will have the correct "A" filament voltage and the B+ will be slightly low. I still don't think that that would make a difference at a low volume.
If I use a diode bridge, two capacitors (47 or 100 microfarads), and a filter choke (I have a bunch of NOS chokes 12 Henries, 70 Ma, 390 ohms.) How's that choke? Will that work to reduce the voltage a little bit? Will it quiet the hum? Or will the hum still be heard if an ear is pressed into the speaker when the volume is turned all the way down. I want to try it. Thinking about it, 70 mA is probably not enough. It's more like 500 mA. But maybe there is a choke that will work.

Thanks,

Dave

Dave,

You can experiment by trying the choke in the place of the resistor between the two electrolytics which is probably 1200 to 1500 ohms resistance. Add a resistor in series with the choke to make up the difference between the choke DC resistance and the old PS resistor. I am pretty sure a choke will reduce the hum better than a resistor alone.

Radiodoc
****************

:Hello All,
: In December 2005 we spoke about this. There someone I know who has a critical ear and wants to listen to good sound from his AC/DC sets at low voume. He's annoyed by the half-wave hum.
: In the discussion we concluded that if the power supply produces 110-125 volts DC, then the tubes will have the correct "A" filament voltage and the B+ will be slightly low. I still don't think that that would make a difference at a low volume.
: If I use a diode bridge, two capacitors (47 or 100 microfarads), and a filter choke (I have a bunch of NOS chokes 12 Henries, 70 Ma, 390 ohms.) How's that choke? Will that work to reduce the voltage a little bit? Will it quiet the hum? Or will the hum still be heard if an ear is pressed into the speaker when the volume is turned all the way down. I want to try it. Thinking about it, 70 mA is probably not enough. It's more like 500 mA. But maybe there is a choke that will work.
:
:Thanks,
:
:Dave

:Dave,
:
:You can experiment by trying the choke in the place of the resistor between the two electrolytics which is probably 1200 to 1500 ohms resistance. Add a resistor in series with the choke to make up the difference between the choke DC resistance and the old PS resistor. I am pretty sure a choke will reduce the hum better than a resistor alone.

Why don't you try this: Get a, oh say 25 Ohm pot and put it in the speaker circuit. Adjust the radio volume a little higher than normal with the pot full volume, but not distorted, and then lower the volume with the speaker pot. No more hum, and a lot less trouble. You might try an external DC supply with your diodes and choke, and run the whole radio on DC, filaments and all. The unloaded DC Voltage will be 1.414 x the line Voltage, but a load will probably drop it to about 120 V. or so. DC on the filaments will for sure lower the hum, and a full wave will give you 120 Hz. instead of 60 to filter. One amp diodes can give you up to 120 Watts of radio to power. Just never plug in a transformer radio into a DC circuit. In my broadcast days, we were known to use DC on preamp fialments for hum reduction.

Lewis L.
:
:Radiodoc
:****************
:
::Hello All,
:: In December 2005 we spoke about this. There someone I know who has a critical ear and wants to listen to good sound from his AC/DC sets at low voume. He's annoyed by the half-wave hum.
:: In the discussion we concluded that if the power supply produces 110-125 volts DC, then the tubes will have the correct "A" filament voltage and the B+ will be slightly low. I still don't think that that would make a difference at a low volume.
:: If I use a diode bridge, two capacitors (47 or 100 microfarads), and a filter choke (I have a bunch of NOS chokes 12 Henries, 70 Ma, 390 ohms.) How's that choke? Will that work to reduce the voltage a little bit? Will it quiet the hum? Or will the hum still be heard if an ear is pressed into the speaker when the volume is turned all the way down. I want to try it. Thinking about it, 70 mA is probably not enough. It's more like 500 mA. But maybe there is a choke that will work.
::
::Thanks,
::
::Dave

Dave

A full wave rectifier with filtering will reduce hum if it's from the power supply. If left this way you radio will be hot. Chassis can not be grounded regardless of plug polarity.

Hum can also get in from filament to signal line capacity or internal tube leakage.

You could try cancelling hum by feeding some inverted into the signal line.

Using a resistor in series with a speaker in interesting. Never though of doing this. It will reduce low frequency response along with the hum.

Norm

::Dave,
::
::You can experiment by trying the choke in the place of the resistor between the two electrolytics which is probably 1200 to 1500 ohms resistance. Add a resistor in series with the choke to make up the difference between the choke DC resistance and the old PS resistor. I am pretty sure a choke will reduce the hum better than a resistor alone.
:
:Why don't you try this: Get a, oh say 25 Ohm pot and put it in the speaker circuit. Adjust the radio volume a little higher than normal with the pot full volume, but not distorted, and then lower the volume with the speaker pot. No more hum, and a lot less trouble. You might try an external DC supply with your diodes and choke, and run the whole radio on DC, filaments and all. The unloaded DC Voltage will be 1.414 x the line Voltage, but a load will probably drop it to about 120 V. or so. DC on the filaments will for sure lower the hum, and a full wave will give you 120 Hz. instead of 60 to filter. One amp diodes can give you up to 120 Watts of radio to power. Just never plug in a transformer radio into a DC circuit. In my broadcast days, we were known to use DC on preamp fialments for hum reduction.
:
:Lewis L.
::
::Radiodoc
::****************
::
:::Hello All,
::: In December 2005 we spoke about this. There someone I know who has a critical ear and wants to listen to good sound from his AC/DC sets at low voume. He's annoyed by the half-wave hum.
::: In the discussion we concluded that if the power supply produces 110-125 volts DC, then the tubes will have the correct "A" filament voltage and the B+ will be slightly low. I still don't think that that would make a difference at a low volume.
::: If I use a diode bridge, two capacitors (47 or 100 microfarads), and a filter choke (I have a bunch of NOS chokes 12 Henries, 70 Ma, 390 ohms.) How's that choke? Will that work to reduce the voltage a little bit? Will it quiet the hum? Or will the hum still be heard if an ear is pressed into the speaker when the volume is turned all the way down. I want to try it. Thinking about it, 70 mA is probably not enough. It's more like 500 mA. But maybe there is a choke that will work.
:::
:::Thanks,
:::
:::Dave

Hello All,
I have another idea. I'll let everyone know what it is after I try it out.

Thanks,

Dave
:Dave
:
: A full wave rectifier with filtering will reduce hum if it's from the power supply. If left this way you radio will be hot. Chassis can not be grounded regardless of plug polarity.
:
: Hum can also get in from filament to signal line capacity or internal tube leakage.
:
: You could try cancelling hum by feeding some inverted into the signal line.
:
: Using a resistor in series with a speaker in interesting. Never though of doing this. It will reduce low frequency response along with the hum.
:
:Norm
:
:::Dave,
:::
:::You can experiment by trying the choke in the place of the resistor between the two electrolytics which is probably 1200 to 1500 ohms resistance. Add a resistor in series with the choke to make up the difference between the choke DC resistance and the old PS resistor. I am pretty sure a choke will reduce the hum better than a resistor alone.
::
::Why don't you try this: Get a, oh say 25 Ohm pot and put it in the speaker circuit. Adjust the radio volume a little higher than normal with the pot full volume, but not distorted, and then lower the volume with the speaker pot. No more hum, and a lot less trouble. You might try an external DC supply with your diodes and choke, and run the whole radio on DC, filaments and all. The unloaded DC Voltage will be 1.414 x the line Voltage, but a load will probably drop it to about 120 V. or so. DC on the filaments will for sure lower the hum, and a full wave will give you 120 Hz. instead of 60 to filter. One amp diodes can give you up to 120 Watts of radio to power. Just never plug in a transformer radio into a DC circuit. In my broadcast days, we were known to use DC on preamp fialments for hum reduction.
::
::Lewis L.
:::
:::Radiodoc
:::****************
:::
::::Hello All,
:::: In December 2005 we spoke about this. There someone I know who has a critical ear and wants to listen to good sound from his AC/DC sets at low voume. He's annoyed by the half-wave hum.
:::: In the discussion we concluded that if the power supply produces 110-125 volts DC, then the tubes will have the correct "A" filament voltage and the B+ will be slightly low. I still don't think that that would make a difference at a low volume.
:::: If I use a diode bridge, two capacitors (47 or 100 microfarads), and a filter choke (I have a bunch of NOS chokes 12 Henries, 70 Ma, 390 ohms.) How's that choke? Will that work to reduce the voltage a little bit? Will it quiet the hum? Or will the hum still be heard if an ear is pressed into the speaker when the volume is turned all the way down. I want to try it. Thinking about it, 70 mA is probably not enough. It's more like 500 mA. But maybe there is a choke that will work.
::::
::::Thanks,
::::
::::Dave

:Hello All,
: I have another idea. I'll let everyone know what it is after I try it out.........................

Ten 12 volt car batteries wired in series ???

73's

Edd,
It's still a power supply but something different.

Dave
::Hello All,
:: I have another idea. I'll let everyone know what it is after I try it out.........................
:
:Ten 12 volt car batteries wired in series ???
:
:73's
:

Dave, check the B+ supply voltages in a systematic manner, and you should be able to pinpoint the problem.

First, check the DC voltage across the filter cap, C1. It should be about 165V or so. If that voltage is OK, then the problem must be downstream from there, e.g., the transistor regulators, zeners, etc.
Doug

Whoops, sorry - posted to the wrong thread. Ignore.

:Dave, check the B+ supply voltages in a systematic manner, and you should be able to pinpoint the problem.
:
:First, check the DC voltage across the filter cap, C1. It should be about 165V or so. If that voltage is OK, then the problem must be downstream from there, e.g., the transistor regulators, zeners, etc.
:Doug

If you power the entire radio from a bridge, the voltages won't be different. It isn't like you're feeding the radio 120 volts steady DC. You're feeding it from a bridge rectifier that's connected to 120 volts AC, and the peaks will still get through, so your B supply will have an unloaded potential of over 150 volts.

I don't think that you need to add any chokes or change resistors to chokes. I built an AC amplifier once that originally called for a field coil type speaker. I built the amplifier strictly using resistors, except for the power and output transformers. There was no speaker field or a hum bucking coil. The field was substituted with a 1800 ohm resistor. The amplifier had almost no hum. Of course in such an amplifier, the entire amplification unit is usually after the filter choke/resistor. In AC/DC radios, the output plate circuit is usually connected directly to the rectifier. Still, you should have some good results. Why not just try it????? The bridge rectifiers are obtained cheaply at Radio Shack. Wire one up and plug it in!

T.

Thomas,
It's a little bit different. it's still a power supply. It may take until next month before I build and try it. But then I'll let everyone know how it worked out.

Thanks,

Dave

:If you power the entire radio from a bridge, the voltages won't be different. It isn't like you're feeding the radio 120 volts steady DC. You're feeding it from a bridge rectifier that's connected to 120 volts AC, and the peaks will still get through, so your B supply will have an unloaded potential of over 150 volts.
:
:I don't think that you need to add any chokes or change resistors to chokes. I built an AC amplifier once that originally called for a field coil type speaker. I built the amplifier strictly using resistors, except for the power and output transformers. There was no speaker field or a hum bucking coil. The field was substituted with a 1800 ohm resistor. The amplifier had almost no hum. Of course in such an amplifier, the entire amplification unit is usually after the filter choke/resistor. In AC/DC radios, the output plate circuit is usually connected directly to the rectifier. Still, you should have some good results. Why not just try it????? The bridge rectifiers are obtained cheaply at Radio Shack. Wire one up and plug it in!
:
:T.

All you do is go to Radio Shack and buy one of those little square bridge rectifier thingies. It might cost $3. Buy a 2 ampere unit or higher. When you get home, solder an old lamp cord to the ~ terminals (AC terminals). Touch the + and - terminals to the prongs of your radio. Plug it in and try it out. If the radio won't work, reverse how its plug is connected to the + and - of the rectifier.

T.

That will give power to operate a radio but only pulsing DC. Pulsing DC will probably cause more noise than AC?

Also be careful as both sides of the line are now hot.

Norm

:All you do is go to Radio Shack and buy one of those little square bridge rectifier thingies. It might cost $3. Buy a 2 ampere unit or higher. When you get home, solder an old lamp cord to the ~ terminals (AC terminals). Touch the + and - terminals to the prongs of your radio. Plug it in and try it out. If the radio won't work, reverse how its plug is connected to the + and - of the rectifier.
:
:T.

So.........for craps and giggles I decided to try this trick out. I had a full wave rectifier lying around. I connected it to the radio. It lit up, but nothing happened. Then I reversed the radio's plug. The radio came to life! The hum was very much less than before. Then I took a 47 MFD 250 WV condenser and put it across the full wave rectifier. The hum disappeared!!!!!!!!!!!!!!!!!!

AMAZING!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Well, then I put a meter across the rectifier, and it turns out that the power is 150 volts even with the entire radio loading it down.......not good for the filaments. What I recommend is that people just wire this to the B circuit, and not to the entire radio. Wire the AC leads with one going to the B- side of the line cord. The other AC lead should go to pin 3 of the 35Z5, so that the pilot lamp will still be in the B circuit. If there is no pilot lamp, the rectifier can simply be wired to pin 2, or to that side of the AC cord. Lift pin 5 of the 35Z5 from wherever it connects (pin 3, usually). Connect it to a 50 ohm resistor, and this to the + side of the bridge. Separate B- from the filament wiring. If B- and the filament wiring connect to the chassis (even if indirectly), leave B- connected to the chassis (even if indirectly), since the chassis must shield in relation to B-. Connect the - side of the bridge to B-. Connect a 47 MFD condenser between pin 5 of the 35Z5 and the - side of the bridge.

The reason why I leave the rectifier tube included in the B circuit is because it adds a little extra resistance between the bridge and the B circuit, which further reduces hum.

You could also save all of the above modifications and just put a resistor in the filament circuit. However, the resistor might add unwanted extra heat.

Also, with the extra B voltage you will get with the bridge rectifier, you can try out a 50C6G, which puts out more power than the 50L6GT.

Actually, I was thinking that if the rectifier is wired into the B circuit only, it will be better to put the 50 ohm resistor on the AC side of the rectifier. This will protect the rectifier against electrolytic surges, and will also protect your home in case the rectifier has an internal short (not impossible...I've seen it happen quite a few times).

If the rectifier is used to power the entire radio, with a dropping resistor in the filament circuit only, it will be best to fuse the rectifier to protect against internal shorts. Also, put a 50 ohm resistor between the + side of the rectifier, and the electrolytic you add on the plate side of the 35Z5.

T.

You can operate the radio directly from the rectifier without any modification at all if you eliminate the additional 47 MFD electrolytic that's placed right at the bridge. Your DC meter will read about 110 volts, and the filaments will all glow normally, because they will be receiving exactly what they'd receive if connected directly to the AC line, but it will all be of positive polarity.

If you do not add the 47 MFD electrolytic, however, there will be a small 120 cycle hum in the speaker.

T.

Or, rather, it will all be of one polarity.

T.

:Actually, I was thinking that if the rectifier is wired into the B circuit only, it will be better to put the 50 ohm resistor on the AC side of the rectifier. This will protect the rectifier against electrolytic surges, and will also protect your home in case the rectifier has an internal short (not impossible...I've seen it happen quite a few times).
:

Thomas :
If you need to drop the AC side why not just use a small non polarized AC capacitor??
... (assuming about a 150 ma load)
4.5 uf will drop 30 vac
5.5 uf = 20 vac drop
8 uf = 10v ac drop

Or just experiment with various AC caps on the AC side till you get the desired voltage level on the DC side.

Hello Thomas, Norm, Edd,
I am expermenting with number 83 tubes for this power supply. So far it looks good. But as was pointed out, the voltage is a bit high and the sound distorts after a short time. This may be because the current isn't high enough. I need about 350mA for the 35-40 watts most AC/DC sets work on.
I have found a suitable Isolation tramsformer. But this one is designed with a dual primary and dual secondary. 115-0-115 on both sides, if the two coils are connected in series. I'm using just one coil on the primary side. I have the two coils on the secondary connected together in series. This provides a connection for the negative terminal and full wave rectification using two 83 tubes. The plates are in parallel so they can handle the current. 250mA is what a plate should be handling nominally. So with the two plates 350mA should be fine, and it seems to be.
For filament I'm using a 5v center tapped 8 amp filament transformer. It gets pretty warm to the touch when it's on a while. I'm probably drawing 6 amps. The voltage when a radio is connected is 147. It really should be more like 120 or 115. Maybe if I add a 1.5 henry choke and another capacitor (Pi filter capacitor input), the voltage should come down a bit. I want to use a resistor but that may limit the current too much. I'll get an ammeter hooked up to it to be sure it's not drawing too much current. The power transformer is only capable of 350mA per winding. So I may have to move up to one that's capable of a little more current.

The hum is now down to a barely noticable level. This is tons better than the built in half wave rectifier. It makes a tremendous difference.
The blue glow looks pretty good too.

If anyone has any suggestions that may help reduce the output voltage a little bit (20 volts or so), please help. Is it ok to use two zener diodes (12 volt 1 amp)? Does solid state mix with tubes?

Thanks,

Dave
:If you power the entire radio from a bridge, the voltages won't be different. It isn't like you're feeding the radio 120 volts steady DC. You're feeding it from a bridge rectifier that's connected to 120 volts AC, and the peaks will still get through, so your B supply will have an unloaded potential of over 150 volts.
:
:I don't think that you need to add any chokes or change resistors to chokes. I built an AC amplifier once that originally called for a field coil type speaker. I built the amplifier strictly using resistors, except for the power and output transformers. There was no speaker field or a hum bucking coil. The field was substituted with a 1800 ohm resistor. The amplifier had almost no hum. Of course in such an amplifier, the entire amplification unit is usually after the filter choke/resistor. In AC/DC radios, the output plate circuit is usually connected directly to the rectifier. Still, you should have some good results. Why not just try it????? The bridge rectifiers are obtained cheaply at Radio Shack. Wire one up and plug it in!
:
:T.

Hello All,
Yes, a 30 volt zener diode brings the voltage to 117V DC. It sounds really good. The radio plays nice and strongly. No noticable strength difference. But the hum has been greatly reduced, which was the purpose of this power supply.

I hope this helps anyone interested in such a power supply. It is expensive. So this is probably for someone who has an extensive collection of AC/DC sets.

This is a standard full-wave (aka. Double-wave) power supply with a capacitor filter and a voltage regulator. The only thing special about it is that it uses two number 83 mercury vapor rectifier tubes. Other tubes, such as a 5U4 or 80, or 5Y3 couldn't work here because of the higher current requirements. Does anyone know of a 4 pin 5 volt duo dilode that doesn't contain Mercury, that also works with "high" current. 350 mA or so is high current for a tube.

Thanks,

Dave
:Hello Thomas, Norm, Edd,
: I am expermenting with number 83 tubes for this power supply. So far it looks good. But as was pointed out, the voltage is a bit high and the sound distorts after a short time. This may be because the current isn't high enough. I need about 350mA for the 35-40 watts most AC/DC sets work on.
: I have found a suitable Isolation tramsformer. But this one is designed with a dual primary and dual secondary. 115-0-115 on both sides, if the two coils are connected in series. I'm using just one coil on the primary side. I have the two coils on the secondary connected together in series. This provides a connection for the negative terminal and full wave rectification using two 83 tubes. The plates are in parallel so they can handle the current. 250mA is what a plate should be handling nominally. So with the two plates 350mA should be fine, and it seems to be.
: For filament I'm using a 5v center tapped 8 amp filament transformer. It gets pretty warm to the touch when it's on a while. I'm probably drawing 6 amps. The voltage when a radio is connected is 147. It really should be more like 120 or 115. Maybe if I add a 1.5 henry choke and another capacitor (Pi filter capacitor input), the voltage should come down a bit. I want to use a resistor but that may limit the current too much. I'll get an ammeter hooked up to it to be sure it's not drawing too much current. The power transformer is only capable of 350mA per winding. So I may have to move up to one that's capable of a little more current.
:
: The hum is now down to a barely noticable level. This is tons better than the built in half wave rectifier. It makes a tremendous difference.
:The blue glow looks pretty good too.
:
: If anyone has any suggestions that may help reduce the output voltage a little bit (20 volts or so), please help. Is it ok to use two zener diodes (12 volt 1 amp)? Does solid state mix with tubes?
:
:Thanks,
:
:Dave
::If you power the entire radio from a bridge, the voltages won't be different. It isn't like you're feeding the radio 120 volts steady DC. You're feeding it from a bridge rectifier that's connected to 120 volts AC, and the peaks will still get through, so your B supply will have an unloaded potential of over 150 volts.
::
::I don't think that you need to add any chokes or change resistors to chokes. I built an AC amplifier once that originally called for a field coil type speaker. I built the amplifier strictly using resistors, except for the power and output transformers. There was no speaker field or a hum bucking coil. The field was substituted with a 1800 ohm resistor. The amplifier had almost no hum. Of course in such an amplifier, the entire amplification unit is usually after the filter choke/resistor. In AC/DC radios, the output plate circuit is usually connected directly to the rectifier. Still, you should have some good results. Why not just try it????? The bridge rectifiers are obtained cheaply at Radio Shack. Wire one up and plug it in!
::
::T.

Tubes look nice, and I'm all for them, but you can make the power supply much more cheaply if you just purchase a full wave rectifier unit from Radio Shack. It costs all of about $3. You can use it either with or without an isolation transformer.

T.

Thomas,
I plan on making the same thing with 1N4007s for rectification and regulation. They cost about 2 cents each in quantity. Not using the tubes would eliminate the, tubes and filament transformer. That would take about $40.00 off the cost. That will also eliminate the look of the cool blue tubes. It could lead to inrush current that would damage my power transformer. This is high current. Nobody makes a 30v 1 amp zener diode. The one that handles 850 mA costs about $25.00. Then there's the cost of the heat sink on top of that. But if I make one myself out of 42 doides, it costs about 84 cents and I don't need a heat sink. If I use a solid state rectifier, I will have to reduce the output by another 15 volts. That will add another 21 diodes to my zener diode for a total of 63 diodes, at a cost of $1.26. Adding a filter choke will cost about $20.00, and may reduce the voltage a bit as well. I don't think I need the choke. A 100 mf capacitor works just fine with the tubes. I don't know what ripple there will be using the solid state diodes instead of the tubes. I assume less or the same.

Dave
:Tubes look nice, and I'm all for them, but you can make the power supply much more cheaply if you just purchase a full wave rectifier unit from Radio Shack. It costs all of about $3. You can use it either with or without an isolation transformer.
:
:T.

Dave,

Check out Mouser PN 863-1N5363BG at www.mouser.com

Radiodoc
***********

:Thomas,
: I plan on making the same thing with 1N4007s for rectification and regulation. They cost about 2 cents each in quantity. Not using the tubes would eliminate the, tubes and filament transformer. That would take about $40.00 off the cost. That will also eliminate the look of the cool blue tubes. It could lead to inrush current that would damage my power transformer. This is high current. Nobody makes a 30v 1 amp zener diode. The one that handles 850 mA costs about $25.00. Then there's the cost of the heat sink on top of that. But if I make one myself out of 42 doides, it costs about 84 cents and I don't need a heat sink. If I use a solid state rectifier, I will have to reduce the output by another 15 volts. That will add another 21 diodes to my zener diode for a total of 63 diodes, at a cost of $1.26. Adding a filter choke will cost about $20.00, and may reduce the voltage a bit as well. I don't think I need the choke. A 100 mf capacitor works just fine with the tubes. I don't know what ripple there will be using the solid state diodes instead of the tubes. I assume less or the same.
:
:Dave
::Tubes look nice, and I'm all for them, but you can make the power supply much more cheaply if you just purchase a full wave rectifier unit from Radio Shack. It costs all of about $3. You can use it either with or without an isolation transformer.
::
::T.

Radiodoc,
That diode (1N5363BG) is only 5 watts. I need about 50 watts. The voltage is 147 and the current is 400 mA. 147 x .4 = 58.8 Watts. That will fry a 5 watt diode. I have it in series. If I put it in parallel, I would need a rather large power resistor, whch would get pretty hot and possibly cut down the current. So I would rather have the zener diode in series. The 1N4007 handles 1 amp. So no problem with the 58 Watts. 147 x 1000 mA = 147 Watts. That's how much the 1N4007s can handle maximum at 147 volts. Even 45 volts x .4 = 18 watts, which is the voltage drop accross the zener, will stll fry the 5 watt zener. I would probably have to put several of them in parallel to get them to handle the current.
The correct zener diode costs over $20.00 and it's a stud type mount. It looks like I' m going to be using a lot of 1N4007s.

Thanks,

Dave

:Dave,
:
:Check out Mouser PN 863-1N5363BG at www.mouser.com
:
:Radiodoc
:***********
:
::Thomas,
:: I plan on making the same thing with 1N4007s for rectification and regulation. They cost about 2 cents each in quantity. Not using the tubes would eliminate the, tubes and filament transformer. That would take about $40.00 off the cost. That will also eliminate the look of the cool blue tubes. It could lead to inrush current that would damage my power transformer. This is high current. Nobody makes a 30v 1 amp zener diode. The one that handles 850 mA costs about $25.00. Then there's the cost of the heat sink on top of that. But if I make one myself out of 42 doides, it costs about 84 cents and I don't need a heat sink. If I use a solid state rectifier, I will have to reduce the output by another 15 volts. That will add another 21 diodes to my zener diode for a total of 63 diodes, at a cost of $1.26. Adding a filter choke will cost about $20.00, and may reduce the voltage a bit as well. I don't think I need the choke. A 100 mf capacitor works just fine with the tubes. I don't know what ripple there will be using the solid state diodes instead of the tubes. I assume less or the same.
::
::Dave
:::Tubes look nice, and I'm all for them, but you can make the power supply much more cheaply if you just purchase a full wave rectifier unit from Radio Shack. It costs all of about $3. You can use it either with or without an isolation transformer.
:::
:::T.

Dave,

Just thought you were having trouble finding a 30 VOLT 1 AMP zener diode.

Radiodoc
***********

:Radiodoc,
: That diode (1N5363BG) is only 5 watts. I need about 50 watts. The voltage is 147 and the current is 400 mA. 147 x .4 = 58.8 Watts. That will fry a 5 watt diode. I have it in series. If I put it in parallel, I would need a rather large power resistor, whch would get pretty hot and possibly cut down the current. So I would rather have the zener diode in series. The 1N4007 handles 1 amp. So no problem with the 58 Watts. 147 x 1000 mA = 147 Watts. That's how much the 1N4007s can handle maximum at 147 volts. Even 45 volts x .4 = 18 watts, which is the voltage drop accross the zener, will stll fry the 5 watt zener. I would probably have to put several of them in parallel to get them to handle the current.
: The correct zener diode costs over $20.00 and it's a stud type mount. It looks like I' m going to be using a lot of 1N4007s.
:
:Thanks,
:
:Dave
:
::Dave,
::
::Check out Mouser PN 863-1N5363BG at www.mouser.com
::
::Radiodoc
::***********
::
:::Thomas,
::: I plan on making the same thing with 1N4007s for rectification and regulation. They cost about 2 cents each in quantity. Not using the tubes would eliminate the, tubes and filament transformer. That would take about $40.00 off the cost. That will also eliminate the look of the cool blue tubes. It could lead to inrush current that would damage my power transformer. This is high current. Nobody makes a 30v 1 amp zener diode. The one that handles 850 mA costs about $25.00. Then there's the cost of the heat sink on top of that. But if I make one myself out of 42 doides, it costs about 84 cents and I don't need a heat sink. If I use a solid state rectifier, I will have to reduce the output by another 15 volts. That will add another 21 diodes to my zener diode for a total of 63 diodes, at a cost of $1.26. Adding a filter choke will cost about $20.00, and may reduce the voltage a bit as well. I don't think I need the choke. A 100 mf capacitor works just fine with the tubes. I don't know what ripple there will be using the solid state diodes instead of the tubes. I assume less or the same.
:::
:::Dave
::::Tubes look nice, and I'm all for them, but you can make the power supply much more cheaply if you just purchase a full wave rectifier unit from Radio Shack. It costs all of about $3. You can use it either with or without an isolation transformer.
::::
::::T.

Hi

Just reading about a 30 volt 1 amp Zener diode. Zener diodes are rated in watts. 30 volts @ 1 amp would be 30 watts but that's not the way to go.

If you really need that kind of power use a 2N3055 transistor wired as emitter follower. Base of the transistor will be tied to a 30 volt 1 watt Zener diode. A resistor from base to B+. Collector of the 2N3055 also to B+. The emitter of the transistor will have regulated 30 volts.

You may not need this much regulation but this is an easy/cheap way.

Norm

:Dave,
:
:Just thought you were having trouble finding a 30 VOLT 1 AMP zener diode.
:
:Radiodoc
:***********
:
::Radiodoc,
:: That diode (1N5363BG) is only 5 watts. I need about 50 watts. The voltage is 147 and the current is 400 mA. 147 x .4 = 58.8 Watts. That will fry a 5 watt diode. I have it in series. If I put it in parallel, I would need a rather large power resistor, whch would get pretty hot and possibly cut down the current. So I would rather have the zener diode in series. The 1N4007 handles 1 amp. So no problem with the 58 Watts. 147 x 1000 mA = 147 Watts. That's how much the 1N4007s can handle maximum at 147 volts. Even 45 volts x .4 = 18 watts, which is the voltage drop accross the zener, will stll fry the 5 watt zener. I would probably have to put several of them in parallel to get them to handle the current.
:: The correct zener diode costs over $20.00 and it's a stud type mount. It looks like I' m going to be using a lot of 1N4007s.
::
::Thanks,
::
::Dave
::
:::Dave,
:::
:::Check out Mouser PN 863-1N5363BG at www.mouser.com
:::
:::Radiodoc
:::***********
:::
::::Thomas,
:::: I plan on making the same thing with 1N4007s for rectification and regulation. They cost about 2 cents each in quantity. Not using the tubes would eliminate the, tubes and filament transformer. That would take about $40.00 off the cost. That will also eliminate the look of the cool blue tubes. It could lead to inrush current that would damage my power transformer. This is high current. Nobody makes a 30v 1 amp zener diode. The one that handles 850 mA costs about $25.00. Then there's the cost of the heat sink on top of that. But if I make one myself out of 42 doides, it costs about 84 cents and I don't need a heat sink. If I use a solid state rectifier, I will have to reduce the output by another 15 volts. That will add another 21 diodes to my zener diode for a total of 63 diodes, at a cost of $1.26. Adding a filter choke will cost about $20.00, and may reduce the voltage a bit as well. I don't think I need the choke. A 100 mf capacitor works just fine with the tubes. I don't know what ripple there will be using the solid state diodes instead of the tubes. I assume less or the same.
::::
::::Dave
:::::Tubes look nice, and I'm all for them, but you can make the power supply much more cheaply if you just purchase a full wave rectifier unit from Radio Shack. It costs all of about $3. You can use it either with or without an isolation transformer.
:::::
:::::T.

Norm,
Some of us have 2N3055s just lying around collecting dust. So this is a very good idea as well. Could you post a picture of this circuit. I remember there was a way to make this adjustable with a control so that for any radio it could be set to exactly 117v DC. I haven't put together one of these in years.

Thanks,

Dave
:Hi
:
: Just reading about a 30 volt 1 amp Zener diode. Zener diodes are rated in watts. 30 volts @ 1 amp would be 30 watts but that's not the way to go.
:
: If you really need that kind of power use a 2N3055 transistor wired as emitter follower. Base of the transistor will be tied to a 30 volt 1 watt Zener diode. A resistor from base to B+. Collector of the 2N3055 also to B+. The emitter of the transistor will have regulated 30 volts.
:
: You may not need this much regulation but this is an easy/cheap way.
:
:Norm
:
:
:
::Dave,
::
::Just thought you were having trouble finding a 30 VOLT 1 AMP zener diode.
::
::Radiodoc
::***********
::
:::Radiodoc,
::: That diode (1N5363BG) is only 5 watts. I need about 50 watts. The voltage is 147 and the current is 400 mA. 147 x .4 = 58.8 Watts. That will fry a 5 watt diode. I have it in series. If I put it in parallel, I would need a rather large power resistor, whch would get pretty hot and possibly cut down the current. So I would rather have the zener diode in series. The 1N4007 handles 1 amp. So no problem with the 58 Watts. 147 x 1000 mA = 147 Watts. That's how much the 1N4007s can handle maximum at 147 volts. Even 45 volts x .4 = 18 watts, which is the voltage drop accross the zener, will stll fry the 5 watt zener. I would probably have to put several of them in parallel to get them to handle the current.
::: The correct zener diode costs over $20.00 and it's a stud type mount. It looks like I' m going to be using a lot of 1N4007s.
:::
:::Thanks,
:::
:::Dave
:::
::::Dave,
::::
::::Check out Mouser PN 863-1N5363BG at www.mouser.com
::::
::::Radiodoc
::::***********
::::
:::::Thomas,
::::: I plan on making the same thing with 1N4007s for rectification and regulation. They cost about 2 cents each in quantity. Not using the tubes would eliminate the, tubes and filament transformer. That would take about $40.00 off the cost. That will also eliminate the look of the cool blue tubes. It could lead to inrush current that would damage my power transformer. This is high current. Nobody makes a 30v 1 amp zener diode. The one that handles 850 mA costs about $25.00. Then there's the cost of the heat sink on top of that. But if I make one myself out of 42 doides, it costs about 84 cents and I don't need a heat sink. If I use a solid state rectifier, I will have to reduce the output by another 15 volts. That will add another 21 diodes to my zener diode for a total of 63 diodes, at a cost of $1.26. Adding a filter choke will cost about $20.00, and may reduce the voltage a bit as well. I don't think I need the choke. A 100 mf capacitor works just fine with the tubes. I don't know what ripple there will be using the solid state diodes instead of the tubes. I assume less or the same.
:::::
:::::Dave
::::::Tubes look nice, and I'm all for them, but you can make the power supply much more cheaply if you just purchase a full wave rectifier unit from Radio Shack. It costs all of about $3. You can use it either with or without an isolation transformer.
::::::
::::::T.

Dave

Here is what's needed. First you don't want to drop more than 70 volts across the 2N3055. Not a problem if you only have 135-145 input and want 117 output. It's voltage difference across a transistor that's limiting.

A 2N3055 can handle up to 115 watts but needs a good heat sink for anything near that.

Connect B+ to the collector. You could use a small resistor in series if voltage is known to be high and for protection. Connect cathode of a Zener, voltage wanted, to base of the 2N3055. Anode of this Zener to B-. Also connect a resistor from base to B+. Set resistance value so the Zener will dissipate around half of it's rating. Regulated B+ comes out the emitter terminal. That's all needed. Of course you can add capacitors as wanted.

If you want an adjustable supply the Zener can be a pot instead. Don't try zero to 115 volt supply with a 2N3055. You will have too much drop across the transistor when voltage out is very low.

You could use a Zener with pot across it. This will give some regulation up to the Zener voltage.

http://www.onsemi.com/pub/Collateral/2N3055-D.PDF

Norm

:Norm,
: Some of us have 2N3055s just lying around collecting dust. So this is a very good idea as well. Could you post a picture of this circuit. I remember there was a way to make this adjustable with a control so that for any radio it could be set to exactly 117v DC. I haven't put together one of these in years.
:
:Thanks,
:
:Dave
::Hi
::
:: Just reading about a 30 volt 1 amp Zener diode. Zener diodes are rated in watts. 30 volts @ 1 amp would be 30 watts but that's not the way to go.
::
:: If you really need that kind of power use a 2N3055 transistor wired as emitter follower. Base of the transistor will be tied to a 30 volt 1 watt Zener diode. A resistor from base to B+. Collector of the 2N3055 also to B+. The emitter of the transistor will have regulated 30 volts.
::
:: You may not need this much regulation but this is an easy/cheap way.
::
::Norm
::
::
::
:::Dave,
:::
:::Just thought you were having trouble finding a 30 VOLT 1 AMP zener diode.
:::
:::Radiodoc
:::***********
:::
::::Radiodoc,
:::: That diode (1N5363BG) is only 5 watts. I need about 50 watts. The voltage is 147 and the current is 400 mA. 147 x .4 = 58.8 Watts. That will fry a 5 watt diode. I have it in series. If I put it in parallel, I would need a rather large power resistor, whch would get pretty hot and possibly cut down the current. So I would rather have the zener diode in series. The 1N4007 handles 1 amp. So no problem with the 58 Watts. 147 x 1000 mA = 147 Watts. That's how much the 1N4007s can handle maximum at 147 volts. Even 45 volts x .4 = 18 watts, which is the voltage drop accross the zener, will stll fry the 5 watt zener. I would probably have to put several of them in parallel to get them to handle the current.
:::: The correct zener diode costs over $20.00 and it's a stud type mount. It looks like I' m going to be using a lot of 1N4007s.
::::
::::Thanks,
::::
::::Dave
::::
:::::Dave,
:::::
:::::Check out Mouser PN 863-1N5363BG at www.mouser.com
:::::
:::::Radiodoc
:::::***********
:::::
::::::Thomas,
:::::: I plan on making the same thing with 1N4007s for rectification and regulation. They cost about 2 cents each in quantity. Not using the tubes would eliminate the, tubes and filament transformer. That would take about $40.00 off the cost. That will also eliminate the look of the cool blue tubes. It could lead to inrush current that would damage my power transformer. This is high current. Nobody makes a 30v 1 amp zener diode. The one that handles 850 mA costs about $25.00. Then there's the cost of the heat sink on top of that. But if I make one myself out of 42 doides, it costs about 84 cents and I don't need a heat sink. If I use a solid state rectifier, I will have to reduce the output by another 15 volts. That will add another 21 diodes to my zener diode for a total of 63 diodes, at a cost of $1.26. Adding a filter choke will cost about $20.00, and may reduce the voltage a bit as well. I don't think I need the choke. A 100 mf capacitor works just fine with the tubes. I don't know what ripple there will be using the solid state diodes instead of the tubes. I assume less or the same.
::::::
::::::Dave
:::::::Tubes look nice, and I'm all for them, but you can make the power supply much more cheaply if you just purchase a full wave rectifier unit from Radio Shack. It costs all of about $3. You can use it either with or without an isolation transformer.
:::::::
:::::::T.

Did anyone read my last post????????????????????????????????????????????????????????????????????????????????????????

All you need are three things: a full wave rectifier unit from Radio Shack, a 100 ohm 10 watt resistor from Radio Shack, and a 47 MFD 250 WVDC electrolytic from some other source. That'll give you 120 volts DC, and your radio WILL NOT HUM AT ALL.

This will work perfectly for any 30 watt radio. You will need other resistor values for larger wattage radios.

T.

Thomas,
Yes I read it but a 40 watt resistor is probably needed. These radios used different amounts of power, some as high as 50 watts, and some as low as 35. I haven't seen one that used 30 watts. Please give me a few examples. The Emerson 520 I believe is a 40 watt radio.
How is a 10 watt resistor going to work? As you said, I would need to find an even larger resistor. This needs to work with any AC/DC radio. The string of diodes doesn't get hot like the resistor because it's so spread out and it can be adjusted to the proper voltage for each radio with a rotary switch or a few voltage taps, and built-in meter. Also I had to move up to a 100 mf capacitor because there was still a hum with a 47 mf when using the tube rectifiers.
I'll try the 100 ohm 10 watt resistor with a solid state rectifier.

Thanks,

Dave
:Did anyone read my last post????????????????????????????????????????????????????????????????????????????????????????
:
:All you need are three things: a full wave rectifier unit from Radio Shack, a 100 ohm 10 watt resistor from Radio Shack, and a 47 MFD 250 WVDC electrolytic from some other source. That'll give you 120 volts DC, and your radio WILL NOT HUM AT ALL.
:
:This will work perfectly for any 30 watt radio. You will need other resistor values for larger wattage radios.
:
:
:
:T.

Most of the AC/DC radios I own with .15 ampere tubes draw 30 watts. My 3-way portables with 117Z6 rectifiers draw 20 watts. I do know that radios with .3 ampere tubes draw more current, and radios with multiple filament strings draw more current, too.

As far as 10 watts is concerned, sure, the whole radio might draw 30 or 40 watts, but the resistor is only dropping a portion of the power. Wattage isn't the same as current. Wattage is amperage times voltage. For instance, although there may be .15 amperes being drawn by each tube in a .15 ampere string, a 12 volt tube is not going to consume as much WATTAGE as a 50 volt tube. ....So, the resistor in series with the radio is only going to consume a portion of the wattage. The radio is going to consume the rest. You don't need a 40 watt resistor on a 30 or 40 watt radio. It's only going to drop a portion of the wattage. If you want to operate the resistor farther down from its maximum operating range (a 100 ohm resistor on a 30 watt radio, with a full voltage of 150 from the rectifier, is going to consume 9 watts), you can parallel two 200 ohm resistors, which will give you a rating of 20 watts at 100 ohms.

You will need different resistance values for different radios, but you don't need wattages equal to what the radios consume. You only need wattages greater than the wattage that will be consumed by the resistor in each case. You can go larger if you want the resistor to run cooler.

Thomas

:Most of the AC/DC radios I own with .15 ampere tubes draw 30 watts. My 3-way portables with 117Z6 rectifiers draw 20 watts. I do know that radios with .3 ampere tubes draw more current, and radios with multiple filament strings draw more current, too.
Thomas,
Ok. I have a bunch of diodes. I also have a 100 ohm 10 watt resistor. I'll try it and see if it works. If it works 4 diodes for the diode bridge is all I'll need.

Thanks,

Dave
:
:As far as 10 watts is concerned, sure, the whole radio might draw 30 or 40 watts, but the resistor is only dropping a portion of the power. Wattage isn't the same as current. Wattage is amperage times voltage. For instance, although there may be .15 amperes being drawn by each tube in a .15 ampere string, a 12 volt tube is not going to consume as much WATTAGE as a 50 volt tube. ....So, the resistor in series with the radio is only going to consume a portion of the wattage. The radio is going to consume the rest. You don't need a 40 watt resistor on a 30 or 40 watt radio. It's only going to drop a portion of the wattage. If you want to operate the resistor farther down from its maximum operating range (a 100 ohm resistor on a 30 watt radio, with a full voltage of 150 from the rectifier, is going to consume 9 watts), you can parallel two 200 ohm resistors, which will give you a rating of 20 watts at 100 ohms.
:
:You will need different resistance values for different radios, but you don't need wattages equal to what the radios consume. You only need wattages greater than the wattage that will be consumed by the resistor in each case. You can go larger if you want the resistor to run cooler.
:
:Thomas

You also need a 47 MFD condenser.

T.

Thomas,
I'm going to use a 100 mfd capacitor. Also, if there's 360 mA being drawn through the resistor the power is a little bit over 10 Watts. So I think at 25 Watt resistor would work better.

Thanks,

Dave
:You also need a 47 MFD condenser.
:
:T.

Thomas,
I tried the type without an isolation transformer. A 100 mf capacitor has to be used on both sides of the power resistor to reduce the residual hum. It still isn't as quiet as the power supply with the two 83s, the power transformer and all the diodes (zener).
I also had to use a line capacitor to get some buzzing out of the sound. I'll end up building all different types of supplies. The next one will have an isolation transformer, and possibly a filter choke.
The simple full-wave supply is better than the radio's internal half-wave supply but I can make it a lot quieter.

Thanks,

Dave
:Thomas,
: I'm going to use a 100 mfd capacitor. Also, if there's 360 mA being drawn through the resistor the power is a little bit over 10 Watts. So I think at 25 Watt resistor would work better.
:
:Thanks,
:
:Dave
::You also need a 47 MFD condenser.
::
::T.

Well, I already tried out a solid state rectifier unit a while back on this post, and it worked perfectly with a 47 MFD across its output. The only problem was that the radio was seeing 150 volts. At any rate, the radio was hum free. All I used was a full wave rectifier unit (about 2 to 3 dollars) and a 47 MFD condenser. To reduce the voltage you can put in a small wire wound resistor of about 10 watts or so. I don't think that anything larger than 100 ohms should be necessary, and 10 watts should do it. You'll need about an 83 ohm resistor to drop 25 volts, and it'll dissipate a little over 7 watts of heat. Maybe a 100 ohm resistor will be better. That'll drop 30 volts at 9 watts. Since 100 ohm resistors are common, picking one up from Radio Shack shouldn't be hard. The only thing out of the three parts mentioned above that they don't carry is the 47 MFD 250 WVDC condenser.

T.