Capacitors in Series

1/15/2007 10:52:28 PMWayne

Hello All...
I need a 10uf 700 volt electrolytic and cannot seem to find a supplier (for my Ranger transmitter).

Anyway, I'd appreciate some advice on using two 20uf 450 volt caps in series to achieve this goal. Is there any reason why this won't be OK?

Does one need to put some type of resistor in parallel with the caps (seems I remember reading this)? If so, what ohm would I need.
Thanks!
Wayne

1/16/2007 9:23:09 AMRadiodoc

Wayne,

You may want to look at:

http://www.oz.net/~coilgun/theory/capacitors2.htm

In the formula it is stated C is uF. I believe it should be in F (Farads).

Radiodoc

:Hello All...
:I need a 10uf 700 volt electrolytic and cannot seem to find a supplier (for my Ranger transmitter).
:
:Anyway, I'd appreciate some advice on using two 20uf 450 volt caps in series to achieve this goal. Is there any reason why this won't be OK?
:
:Does one need to put some type of resistor in parallel with the caps (seems I remember reading this)? If so, what ohm would I need.
:Thanks!
:Wayne

1/16/2007 9:53:54 AMLewis L.

:Wayne,
:
:You may want to look at:
:
:http://www.oz.net/~coilgun/theory/capacitors2.htm
:
:In the formula it is stated C is uF. I believe it should be in F (Farads).
:
:Radiodoc
:
:
::Hello All...
::I need a 10uf 700 volt electrolytic and cannot seem to find a supplier (for my Ranger transmitter).
::
::Anyway, I'd appreciate some advice on using two 20uf 450 volt caps in series to achieve this goal. Is there any reason why this won't be OK?
::
::Does one need to put some type of resistor in parallel with the caps (seems I remember reading this)? If so, what ohm would I need.
::Thanks!
::Wayne

About 10K, 1/2 Watt ought to do it. This will assure equal Voltages across each cap. Caps in series are like resistors in parallel, that is 1/Ct=(1/C1+1/C2...), so two 20s at 450 will = 1 10 at 800.
Lewis L.

1/16/2007 4:09:23 PMeasyide8

::Wayne,
::
::You may want to look at:
::
::http://www.oz.net/~coilgun/theory/capacitors2.htm
::
::In the formula it is stated C is uF. I believe it should be in F (Farads).
::
::Radiodoc
::
::
:::Hello All...
:::I need a 10uf 700 volt electrolytic and cannot seem to find a supplier (for my Ranger transmitter).
:::
:::Anyway, I'd appreciate some advice on using two 20uf 450 volt caps in series to achieve this goal. Is there any reason why this won't be OK?
:::
:::Does one need to put some type of resistor in parallel with the caps (seems I remember reading this)? If so, what ohm would I need.
:::Thanks!
:::Wayne
:
:About 10K, 1/2 Watt ought to do it. This will assure equal Voltages across each cap. Caps in series are like resistors in parallel, that is 1/Ct=(1/C1+1/C2...), so two 20s at 450 will = 1 10 at 800.
:Lewis L.

______________________________________________________________

You will want to use 2 watt resistors, 1/2 watt resistors are only rated for about 250 volts. Yep resistors have voltage ratings too.

Dave

1/16/2007 8:55:43 PMWayne

:::Wayne,
:::
:::You may want to look at:
:::
:::http://www.oz.net/~coilgun/theory/capacitors2.htm
:::
:::In the formula it is stated C is uF. I believe it should be in F (Farads).
:::
:::Radiodoc
:::
:::
::::Hello All...
::::I need a 10uf 700 volt electrolytic and cannot seem to find a supplier (for my Ranger transmitter).
::::
::::Anyway, I'd appreciate some advice on using two 20uf 450 volt caps in series to achieve this goal. Is there any reason why this won't be OK?
::::
::::Does one need to put some type of resistor in parallel with the caps (seems I remember reading this)? If so, what ohm would I need.
::::Thanks!
::::Wayne
::
::About 10K, 1/2 Watt ought to do it. This will assure equal Voltages across each cap. Caps in series are like resistors in parallel, that is 1/Ct=(1/C1+1/C2...), so two 20s at 450 will = 1 10 at 800.
::Lewis L.
:
:______________________________________________________________
:
:You will want to use 2 watt resistors, 1/2 watt resistors are only rated for about 250 volts. Yep resistors have voltage ratings too.
:
:Dave

Thanks! That is very helpful...
Just so I have this correct, if I'm using two caps in series, I'm to put a resistor across each cap individually... (i.e. two resistors and two capacitors) and not one resistor parallel with two caps?
Thanks again.
Wayne

1/16/2007 9:10:08 PMLewis L.

::::Wayne,
::::
::::You may want to look at:
::::
::::http://www.oz.net/~coilgun/theory/capacitors2.htm
::::
::::In the formula it is stated C is uF. I believe it should be in F (Farads).
::::
::::Radiodoc
::::
::::
:::::Hello All...
:::::I need a 10uf 700 volt electrolytic and cannot seem to find a supplier (for my Ranger transmitter).
:::::
:::::Anyway, I'd appreciate some advice on using two 20uf 450 volt caps in series to achieve this goal. Is there any reason why this won't be OK?
:::::
:::::Does one need to put some type of resistor in parallel with the caps (seems I remember reading this)? If so, what ohm would I need.
:::::Thanks!
:::::Wayne
:::
:::About 10K, 1/2 Watt ought to do it. This will assure equal Voltages across each cap. Caps in series are like resistors in parallel, that is 1/Ct=(1/C1+1/C2...), so two 20s at 450 will = 1 10 at 800.
:::Lewis L.
::
::______________________________________________________________
::
::You will want to use 2 watt resistors, 1/2 watt resistors are only rated for about 250 volts. Yep resistors have voltage ratings too.
::
::Dave
:
:Thanks! That is very helpful...
:Just so I have this correct, if I'm using two caps in series, I'm to put a resistor across each cap individually... (i.e. two resistors and two capacitors) and not one resistor parallel with two caps?
:Thanks again.
:Wayne

Yes, that would be two resistors one across each cap. Also, Dave is right, I got the Voltage wrong, the correction in the wrong place and the Wattage wrong. All I can say is that I have a chest infection, and the doc has me on enough drugs to open my own store. The cough syrup is under lock and key by my wife.
Also, the resistors will slowly discharge the caps, (bleeder resistors) may keep you from working on a radio that has been off all night and knocking....well, you know.

Lewis

1/16/2007 10:57:22 PMRadiodoc

:::::Wayne,
:::::
:::::You may want to look at:
:::::
:::::http://www.oz.net/~coilgun/theory/capacitors2.htm
:::::
:::::In the formula it is stated C is uF. I believe it should be in F (Farads).
:::::
:::::Radiodoc
:::::
:::::
::::::Hello All...
::::::I need a 10uf 700 volt electrolytic and cannot seem to find a supplier (for my Ranger transmitter).
::::::
::::::Anyway, I'd appreciate some advice on using two 20uf 450 volt caps in series to achieve this goal. Is there any reason why this won't be OK?
::::::
::::::Does one need to put some type of resistor in parallel with the caps (seems I remember reading this)? If so, what ohm would I need.
::::::Thanks!
::::::Wayne
::::
::::About 10K, 1/2 Watt ought to do it. This will assure equal Voltages across each cap. Caps in series are like resistors in parallel, that is 1/Ct=(1/C1+1/C2...), so two 20s at 450 will = 1 10 at 800.
::::Lewis L.
:::
:::______________________________________________________________
:::
:::You will want to use 2 watt resistors, 1/2 watt resistors are only rated for about 250 volts. Yep resistors have voltage ratings too.
:::
:::Dave
::
::Thanks! That is very helpful...
::Just so I have this correct, if I'm using two caps in series, I'm to put a resistor across each cap individually... (i.e. two resistors and two capacitors) and not one resistor parallel with two caps?
::Thanks again.
::Wayne
:
:Yes, that would be two resistors one across each cap. Also, Dave is right, I got the Voltage wrong, the correction in the wrong place and the Wattage wrong. All I can say is that I have a chest infection, and the doc has me on enough drugs to open my own store. The cough syrup is under lock and key by my wife.
:Also, the resistors will slowly discharge the caps, (bleeder resistors) may keep you from working on a radio that has been off all night and knocking....well, you know.
:
:Lewis

Lewis,

Isn't 20K Ohms kind of a low value of resistance to put across a 500 volt source?

Radiodoc

1/17/2007 11:00:37 AMLewis Linson

::::::Wayne,
::::::
::::::You may want to look at:
::::::
::::::http://www.oz.net/~coilgun/theory/capacitors2.htm
::::::
::::::In the formula it is stated C is uF. I believe it should be in F (Farads).
::::::
::::::Radiodoc
::::::
::::::
:::::::Hello All...
:::::::I need a 10uf 700 volt electrolytic and cannot seem to find a supplier (for my Ranger transmitter).
:::::::
:::::::Anyway, I'd appreciate some advice on using two 20uf 450 volt caps in series to achieve this goal. Is there any reason why this won't be OK?
:::::::
:::::::Does one need to put some type of resistor in parallel with the caps (seems I remember reading this)? If so, what ohm would I need.
:::::::Thanks!
:::::::Wayne
:::::
:::::About 10K, 1/2 Watt ought to do it. This will assure equal Voltages across each cap. Caps in series are like resistors in parallel, that is 1/Ct=(1/C1+1/C2...), so two 20s at 450 will = 1 10 at 800.
:::::Lewis L.
::::
::::______________________________________________________________
::::
::::You will want to use 2 watt resistors, 1/2 watt resistors are only rated for about 250 volts. Yep resistors have voltage ratings too.
::::
::::Dave
:::
:::Thanks! That is very helpful...
:::Just so I have this correct, if I'm using two caps in series, I'm to put a resistor across each cap individually... (i.e. two resistors and two capacitors) and not one resistor parallel with two caps?
:::Thanks again.
:::Wayne
::
::Yes, that would be two resistors one across each cap. Also, Dave is right, I got the Voltage wrong, the correction in the wrong place and the Wattage wrong. All I can say is that I have a chest infection, and the doc has me on enough drugs to open my own store. The cough syrup is under lock and key by my wife.
::Also, the resistors will slowly discharge the caps, (bleeder resistors) may keep you from working on a radio that has been off all night and knocking....well, you know.
::
::Lewis
:
:Lewis,
:
:Isn't 20K Ohms kind of a low value of resistance to put across a 500 volt source?
:
:Radiodoc

You might be right about that, higher would be better, say 47K maybe, but use something to equalize the Voltages across the caps.
:

1/17/2007 3:17:07 PMLewis L.

:::::::Wayne,
:::::::
:::::::You may want to look at:
:::::::
:::::::http://www.oz.net/~coilgun/theory/capacitors2.htm
:::::::
:::::::In the formula it is stated C is uF. I believe it should be in F (Farads).
:::::::
:::::::Radiodoc
:::::::
:::::::
::::::::Hello All...
::::::::I need a 10uf 700 volt electrolytic and cannot seem to find a supplier (for my Ranger transmitter).
::::::::
::::::::Anyway, I'd appreciate some advice on using two 20uf 450 volt caps in series to achieve this goal. Is there any reason why this won't be OK?
::::::::
::::::::Does one need to put some type of resistor in parallel with the caps (seems I remember reading this)? If so, what ohm would I need.
::::::::Thanks!
::::::::Wayne
::::::
::::::About 10K, 1/2 Watt ought to do it. This will assure equal Voltages across each cap. Caps in series are like resistors in parallel, that is 1/Ct=(1/C1+1/C2...), so two 20s at 450 will = 1 10 at 800.
::::::Lewis L.
:::::
:::::______________________________________________________________
:::::
:::::You will want to use 2 watt resistors, 1/2 watt resistors are only rated for about 250 volts. Yep resistors have voltage ratings too.
:::::
:::::Dave
::::
::::Thanks! That is very helpful...
::::Just so I have this correct, if I'm using two caps in series, I'm to put a resistor across each cap individually... (i.e. two resistors and two capacitors) and not one resistor parallel with two caps?
::::Thanks again.
::::Wayne
:::
:::Yes, that would be two resistors one across each cap. Also, Dave is right, I got the Voltage wrong, the correction in the wrong place and the Wattage wrong. All I can say is that I have a chest infection, and the doc has me on enough drugs to open my own store. The cough syrup is under lock and key by my wife.
:::Also, the resistors will slowly discharge the caps, (bleeder resistors) may keep you from working on a radio that has been off all night and knocking....well, you know.
:::
:::Lewis
::
::Lewis,
::
::Isn't 20K Ohms kind of a low value of resistance to put across a 500 volt source?
::
::Radiodoc
:
:You might be right about that, higher would be better, say 47K maybe, but use something to equalize the Voltages across the caps.
I know where I got that. The last place I worked before retirement was in aviation, and strobe lights were one of my jobs. One unit used 10K across the series caps, but the caps only had full voltage (400V on two 250V. caps in series)for about 100 ms before the tube fired and discharged them to less than 100 V. Then they would charge back up to 400V. and the tube would flash again 1 sec. later. They were also used for bleeders, as the box was in the plane, and the tubes were on the wingtips and tail, and they didn't want to be knocking people off ladders with 400 Volts./
Lewis L.
::

1/16/2007 9:21:01 PMRadiodoc

Wayne,

What is the DC voltage that will be applied to the caps?

Radiodoc

1/16/2007 10:32:00 PMWayne

:::::Wayne,
:::::
:::::You may want to look at:
:::::
:::::http://www.oz.net/~coilgun/theory/capacitors2.htm
:::::
:::::In the formula it is stated C is uF. I believe it should be in F (Farads).
:::::
:::::Radiodoc
:::::
:::::
::::::Hello All...
::::::I need a 10uf 700 volt electrolytic and cannot seem to find a supplier (for my Ranger transmitter).
::::::
::::::Anyway, I'd appreciate some advice on using two 20uf 450 volt caps in series to achieve this goal. Is there any reason why this won't be OK?
::::::
::::::Does one need to put some type of resistor in parallel with the caps (seems I remember reading this)? If so, what ohm would I need.
::::::Thanks!
::::::Wayne
::::
::::About 10K, 1/2 Watt ought to do it. This will assure equal Voltages across each cap. Caps in series are like resistors in parallel, that is 1/Ct=(1/C1+1/C2...), so two 20s at 450 will = 1 10 at 800.
::::Lewis L.
:::
:::______________________________________________________________
:::
:::You will want to use 2 watt resistors, 1/2 watt resistors are only rated for about 250 volts. Yep resistors have voltage ratings too.
:::
:::Dave
::
::Thanks! That is very helpful...
::Just so I have this correct, if I'm using two caps in series, I'm to put a resistor across each cap individually... (i.e. two resistors and two capacitors) and not one resistor parallel with two caps?
::Thanks again.
::Wayne
:
:Wayne,
:
:What is the DC voltage that will be applied to the caps?
:
:Radiodoc
:
Thanks again guys.
It looks like about 500 volts... the one that I'm replacing is rated at 700 volts.
Thanks
Wayne

1/18/2007 11:03:15 PMWayne

::::::Wayne,
::::::
::::::You may want to look at:
::::::
::::::http://www.oz.net/~coilgun/theory/capacitors2.htm
::::::
::::::In the formula it is stated C is uF. I believe it should be in F (Farads).
::::::
::::::Radiodoc
::::::
::::::
:::::::Hello All...
:::::::I need a 10uf 700 volt electrolytic and cannot seem to find a supplier (for my Ranger transmitter).
:::::::
:::::::Anyway, I'd appreciate some advice on using two 20uf 450 volt caps in series to achieve this goal. Is there any reason why this won't be OK?
:::::::
:::::::Does one need to put some type of resistor in parallel with the caps (seems I remember reading this)? If so, what ohm would I need.
:::::::Thanks!
:::::::Wayne
:::::
:::::About 10K, 1/2 Watt ought to do it. This will assure equal Voltages across each cap. Caps in series are like resistors in parallel, that is 1/Ct=(1/C1+1/C2...), so two 20s at 450 will = 1 10 at 800.
:::::Lewis L.
::::
::::______________________________________________________________
::::
::::You will want to use 2 watt resistors, 1/2 watt resistors are only rated for about 250 volts. Yep resistors have voltage ratings too.
::::
::::Dave
:::
:::Thanks! That is very helpful...
:::Just so I have this correct, if I'm using two caps in series, I'm to put a resistor across each cap individually... (i.e. two resistors and two capacitors) and not one resistor parallel with two caps?
:::Thanks again.
:::Wayne
::
::Wayne,
::
::What is the DC voltage that will be applied to the caps?
::
::Radiodoc
::
:Thanks again guys.
:It looks like about 500 volts... the one that I'm replacing is rated at 700 volts.
:Thanks
:Wayne

One last question guys... I did use two 20uf 450volt caps in series(with a 10K 5 watt resistor in parallel with each). This arrangement appears to work fine. However, even the 5 watt (wire wound) resistors get much too hot to touch (shortly after it is unplugged). Should they get this hot?
Thanks
Wayne

1/18/2007 11:13:14 PMRadiodoc

:::::::Wayne,
:::::::
:::::::You may want to look at:
:::::::
:::::::http://www.oz.net/~coilgun/theory/capacitors2.htm
:::::::
:::::::In the formula it is stated C is uF. I believe it should be in F (Farads).
:::::::
:::::::Radiodoc
:::::::
:::::::
::::::::Hello All...
::::::::I need a 10uf 700 volt electrolytic and cannot seem to find a supplier (for my Ranger transmitter).
::::::::
::::::::Anyway, I'd appreciate some advice on using two 20uf 450 volt caps in series to achieve this goal. Is there any reason why this won't be OK?
::::::::
::::::::Does one need to put some type of resistor in parallel with the caps (seems I remember reading this)? If so, what ohm would I need.
::::::::Thanks!
::::::::Wayne
::::::
::::::About 10K, 1/2 Watt ought to do it. This will assure equal Voltages across each cap. Caps in series are like resistors in parallel, that is 1/Ct=(1/C1+1/C2...), so two 20s at 450 will = 1 10 at 800.
::::::Lewis L.
:::::
:::::______________________________________________________________
:::::
:::::You will want to use 2 watt resistors, 1/2 watt resistors are only rated for about 250 volts. Yep resistors have voltage ratings too.
:::::
:::::Dave
::::
::::Thanks! That is very helpful...
::::Just so I have this correct, if I'm using two caps in series, I'm to put a resistor across each cap individually... (i.e. two resistors and two capacitors) and not one resistor parallel with two caps?
::::Thanks again.
::::Wayne
:::
:::Wayne,
:::
:::What is the DC voltage that will be applied to the caps?
:::
:::Radiodoc
:::
::Thanks again guys.
::It looks like about 500 volts... the one that I'm replacing is rated at 700 volts.
::Thanks
::Wayne
:
:One last question guys... I did use two 20uf 450volt caps in series(with a 10K 5 watt resistor in parallel with each). This arrangement appears to work fine. However, even the 5 watt (wire wound) resistors get much too hot to touch (shortly after it is unplugged). Should they get this hot?
:Thanks
:Wayne

Wayne,

A 47000 to 50000 Ohm resistor across each cap may be better.

Radiodoc