I changed the eye socket in my Airline 14WG-806A to an octal so that it could receive a 6E5C, which I have plenty of. Upon first restoring the set I used it extensively to listen to music on my laptop (pandora.com). The eye was wired as the original was wired. After a few months of use I removed the eye and tested it on my tube tester. As it was always 'open' due to my not using the radio portion of the set, the small section of the eye was not illuminated during use. On my tester this section was noticeably brighter than the used section, and so it was evident that extensive use wears out the phosphor.
I then added a resistor to the heater circuit to reduce the heater to about 3 volts. I found that 3 volts would still produce a fully bright target on my tube tester. I also connected the B+ connection of the eye directly to one of the radio's rectifier plates instead of its cathode, so that the eye would receive AC instead of filtered DC. Since the tube will only pass current in one direction, it will actually see half wave unfiltered DC (a separate rectifier is unnecessary). I then inserted an unused 6E5C, with even brilliance over its entire target area (with pie section closed). As wired the tube took a bit longer to light up, but still lit to normal brilliance. I wanted to see if a pulsating B voltage and reduced cathode temperature might prolong the life of the tube (though from what I found on the first tube, it was phosphor burning and not cathode emission reduction that was causing the dimming).
...So I went on to use the radio extensively to listen to my music, with the eye tube in the 'open' position, as I was only using the radio's amplifier and not the RF section, so no station was tuned in. Then, after extensive use I pulled the eye tube and tested it in both the open and closed positions. The small pie wedge section was noticeably brighter than the larger normally illuminated section, and so none of what I did helped to prolong the life of the phosphor, and, as can be seen, dimming of eye tubes is caused by phosphor burn and not wearing of the cathode. Often you will find barely glowing eye tubes in which the pie wedge section still glows fairly brightly.
....Not sure what can be done to reduce this problem, as the vacuum fluorescent displays in VCRs, microwaves, DVD players, stereos, and even automobiles will display numbers faithfully for years and even decades, but, for some strange reason, the phosphor in magic eye tubes wears out rather quickly. I guess it depends on the phosphor used, as I have an RCA eye tube in my Crosley Super 11 that's been in there for a decade now, with plenty of use, and it's still somewhat visible, but the Russian 6E5C tubes wear out more quickly. Eye tubes in general, though, tend to wear out quickly. It would be nice if they used a phosphor like that used in a VFD or picture tube.
T.
With all the many radios I have restored, I have found eyes tubes in various stages of deterioration.I am not sure if one brand is any better than another.
Usually i can tell if a chassis has a lot of hours on it ( melted wax caps , tar from the power xfrmr) and these are the ones with the dimmer tubes.
Lou
:A while ago I posted something regarding perhaps extending the life of a magic eye tube by dimming its cathode and feeding it pulsing B voltage.
:
:I changed the eye socket in my Airline 14WG-806A to an octal so that it could receive a 6E5C, which I have plenty of. Upon first restoring the set I used it extensively to listen to music on my laptop (pandora.com). The eye was wired as the original was wired. After a few months of use I removed the eye and tested it on my tube tester. As it was always 'open' due to my not using the radio portion of the set, the small section of the eye was not illuminated during use. On my tester this section was noticeably brighter than the used section, and so it was evident that extensive use wears out the phosphor.
:
:I then added a resistor to the heater circuit to reduce the heater to about 3 volts. I found that 3 volts would still produce a fully bright target on my tube tester. I also connected the B+ connection of the eye directly to one of the radio's rectifier plates instead of its cathode, so that the eye would receive AC instead of filtered DC. Since the tube will only pass current in one direction, it will actually see half wave unfiltered DC (a separate rectifier is unnecessary). I then inserted an unused 6E5C, with even brilliance over its entire target area (with pie section closed). As wired the tube took a bit longer to light up, but still lit to normal brilliance. I wanted to see if a pulsating B voltage and reduced cathode temperature might prolong the life of the tube (though from what I found on the first tube, it was phosphor burning and not cathode emission reduction that was causing the dimming).
:
:...So I went on to use the radio extensively to listen to my music, with the eye tube in the 'open' position, as I was only using the radio's amplifier and not the RF section, so no station was tuned in. Then, after extensive use I pulled the eye tube and tested it in both the open and closed positions. The small pie wedge section was noticeably brighter than the larger normally illuminated section, and so none of what I did helped to prolong the life of the phosphor, and, as can be seen, dimming of eye tubes is caused by phosphor burn and not wearing of the cathode. Often you will find barely glowing eye tubes in which the pie wedge section still glows fairly brightly.
:
:....Not sure what can be done to reduce this problem, as the vacuum fluorescent displays in VCRs, microwaves, DVD players, stereos, and even automobiles will display numbers faithfully for years and even decades, but, for some strange reason, the phosphor in magic eye tubes wears out rather quickly. I guess it depends on the phosphor used, as I have an RCA eye tube in my Crosley Super 11 that's been in there for a decade now, with plenty of use, and it's still somewhat visible, but the Russian 6E5C tubes wear out more quickly. Eye tubes in general, though, tend to wear out quickly. It would be nice if they used a phosphor like that used in a VFD or picture tube.
:
:T.
:
Interesting experiment with AC on the target. Wonder if a smaller pulse will still show green?
Starting with low target voltage and increasing it as a tube ages works to extend life of the green. At some point the green is still too dim.
I figured it takes about 1000 hours (6 weeks) of use to lose much of the green. You have proven it...
Norm
:Tom:
:
:With all the many radios I have restored, I have found eyes tubes in various stages of deterioration.I am not sure if one brand is any better than another.
:Usually i can tell if a chassis has a lot of hours on it ( melted wax caps , tar from the power xfrmr) and these are the ones with the dimmer tubes.
:
:Lou
:
::A while ago I posted something regarding perhaps extending the life of a magic eye tube by dimming its cathode and feeding it pulsing B voltage.
::
::I changed the eye socket in my Airline 14WG-806A to an octal so that it could receive a 6E5C, which I have plenty of. Upon first restoring the set I used it extensively to listen to music on my laptop (pandora.com). The eye was wired as the original was wired. After a few months of use I removed the eye and tested it on my tube tester. As it was always 'open' due to my not using the radio portion of the set, the small section of the eye was not illuminated during use. On my tester this section was noticeably brighter than the used section, and so it was evident that extensive use wears out the phosphor.
::
::I then added a resistor to the heater circuit to reduce the heater to about 3 volts. I found that 3 volts would still produce a fully bright target on my tube tester. I also connected the B+ connection of the eye directly to one of the radio's rectifier plates instead of its cathode, so that the eye would receive AC instead of filtered DC. Since the tube will only pass current in one direction, it will actually see half wave unfiltered DC (a separate rectifier is unnecessary). I then inserted an unused 6E5C, with even brilliance over its entire target area (with pie section closed). As wired the tube took a bit longer to light up, but still lit to normal brilliance. I wanted to see if a pulsating B voltage and reduced cathode temperature might prolong the life of the tube (though from what I found on the first tube, it was phosphor burning and not cathode emission reduction that was causing the dimming).
::
::...So I went on to use the radio extensively to listen to my music, with the eye tube in the 'open' position, as I was only using the radio's amplifier and not the RF section, so no station was tuned in. Then, after extensive use I pulled the eye tube and tested it in both the open and closed positions. The small pie wedge section was noticeably brighter than the larger normally illuminated section, and so none of what I did helped to prolong the life of the phosphor, and, as can be seen, dimming of eye tubes is caused by phosphor burn and not wearing of the cathode. Often you will find barely glowing eye tubes in which the pie wedge section still glows fairly brightly.
::
::....Not sure what can be done to reduce this problem, as the vacuum fluorescent displays in VCRs, microwaves, DVD players, stereos, and even automobiles will display numbers faithfully for years and even decades, but, for some strange reason, the phosphor in magic eye tubes wears out rather quickly. I guess it depends on the phosphor used, as I have an RCA eye tube in my Crosley Super 11 that's been in there for a decade now, with plenty of use, and it's still somewhat visible, but the Russian 6E5C tubes wear out more quickly. Eye tubes in general, though, tend to wear out quickly. It would be nice if they used a phosphor like that used in a VFD or picture tube.
::
::T.
::
:
:
Best Regards,
Bill Grimm
T.
:D
T.
What about a timing circuit that interrupts the B+ more like a 10% duty cycle. Perhaps the persistence of the phosphor's illumination would make the display seem constant, but with less degradation.
How difficult would it be to build new eye tubes from scratch, using longer-life phosphors? Many vacuum tubes are now being manufactured in Russia, China, etc.
Or, circumcise a depleted tube, and apply new phosphor? But, then, how to seal and evacuate? Does it really need to be evacuated?
What's involved in changing the pie wedge to the opposite side of the tube? I think I've experienced this when testing eye tubes.
Would heat, e.g. in an oven, rejuvenate the phosphor?
I save my old eye tubes so that one day I may be brave enough to open them up and experiment. I also save various other dud tubes of more importance and rarity so that I may someday repair them, too. I recently accidentally cracked a 6D8G that is otherwise perfectly functional, so it will be interesting to try to mend the crack with a torch and then evacuate and bake the tube. I'll have to find a good vacuum pump. I have used the inlet side of my 1920s Kellogg compressor to evacuate air conditioners prior to filling with refrigerant, but I don't think that it can get down past about 29.5 inches of mercury, which isn't very thorough, I think.
T.
Are we totally sure it's only the plate voltage that burn the eye tubes with time ? and not the heating that burn ? Heating is burning no ?
May be another test for you Thomas: Try to cool down your 6E5 with a Peltier module and a little fan to see if phosphor will remains bright with the time...
I also intensively use the amplifier on my Crosley. I feed it with an old 8X CD drive that i put on the top of the cabinet. I was planning to simply add a switch to cut off the heating element of my 6E5 or a switch to cut off the plate voltage..i wonder which one is the best ...
:I should add, in case anyone else does, for some reason, want to reduce the heater voltage of their eye tube, that it was actually 5 volts and not 3 volts that still allowed for a fully lit display. However, reducing voltage did nothing to prolong the life of the phosphor as far as I can see. Another article mentioned ion bombardment, and so it would be interesting to place a magnet near the eye to deter ions (not sure where it'd be placed), but placing a magnet near the display would also warp the display. I'll try it, though, and see what I come up with. Perhaps a magnet right in the center would do, but I think that might just wipe it out or something.
:
:T.
:
http://www.dialcover.com/eyetube.html
Bob Masse
:
:
The eye tube on my Airline 14WG-806A definitely has burn-in from being used, as one part (the unused part) is brighter than the rest.
I do know that VFDs often have a somewhat smoked piece of plastic over them, which may reduce ultraviolet light.
The eye on my Super Silvertone Radio Recorder radio/phonograph wore out evenly. I always leave the lid open, so it could be from sunlight (I live on the 3rd floor), but since the eye moves with recorded music, pretty much the entire display is being used constantly, and I play a lot of records (I use it almost every day, and have for at least 12 years now).
The eye on my Crosley Super 11 also wore out fairly evenly from what I can tell. It isn't completely dark, but it isn't that bright, either. I used to use the radio a lot back when AM was good listening, so that would make for varying amounts of use of the display, but now I just feed music in through the amplifier, so the eye tends to sit more stationary. The radio portion is functional when I'm using it, though (unlike the Airline 14WG-806A), so the eye is still moving around even though I'm not listening to the radio, and sometimes I move the dial around.
It would be interesting to both cycle an eye tube at a low frequency and place a piece of smoked glass in front of it.
T.
You can cycle it with a half wave of any freq, and the duty cycle (percent time on) will still be 50%. My theory is that a pulse-width modulated B+ would be best - that would enable the duty cycle to be varied.
:It would be interesting to both cycle an eye tube at a low frequency and place a piece of smoked glass in front of it.
:
:T.
:
Regarding cycling, however, I tried humming and fluttering my tongue while in a 2004 Dodge Ram, which has a VFD for the odometer and transmission indicator, but the numbers wouldn't dance, so either it isn't necessary to cycle the phosphor in a car since it isn't used continuously, or it doesn't do anything for the longevity of the phosphor. I believe that these displays use lower voltages, which might help reduce ion emission, if ion bombardment is what destroys the phosphor, as is the case with CRTs.
I think it might be a different kind of VFD, too, as there are no grids in front of the numbers, as there are in my parents' microwave, so they may just have a lead for each segment of each number. The VFD on the microwave has all of the like segments of each number tied together to a single terminal. The terminals are cycled in sequence, and the grids that are in front of each number are either unbiased or at cut-off, depending on whether the particular segment that is currently being cycled is supposed to be illuminated or not. ...So the cycling may simply have to do with the particular method of display. I imagine that this type of display might prove annoying to a driver, as it would tend to dance with every vibration of the vehicle, though the reason why this type of display isn't used in vehicles may not have anything to do with this at all. I have noticed that in many vehicles the display is rather steady, though, and doesn't jitter like the one you'd see on home appliances.
...Still, pulse width modulating the eye tube display would reduce the time it was illuminated, and might very well prove to prolong its life.
T.
marv
:A while ago I posted something regarding perhaps extending the life of a magic eye tube by dimming its cathode and feeding it pulsing B voltage.
:
:I changed the eye socket in my Airline 14WG-806A to an octal so that it could receive a 6E5C, which I have plenty of. Upon first restoring the set I used it extensively to listen to music on my laptop (pandora.com). The eye was wired as the original was wired. After a few months of use I removed the eye and tested it on my tube tester. As it was always 'open' due to my not using the radio portion of the set, the small section of the eye was not illuminated during use. On my tester this section was noticeably brighter than the used section, and so it was evident that extensive use wears out the phosphor.
:
:I then added a resistor to the heater circuit to reduce the heater to about 3 volts. I found that 3 volts would still produce a fully bright target on my tube tester. I also connected the B+ connection of the eye directly to one of the radio's rectifier plates instead of its cathode, so that the eye would receive AC instead of filtered DC. Since the tube will only pass current in one direction, it will actually see half wave unfiltered DC (a separate rectifier is unnecessary). I then inserted an unused 6E5C, with even brilliance over its entire target area (with pie section closed). As wired the tube took a bit longer to light up, but still lit to normal brilliance. I wanted to see if a pulsating B voltage and reduced cathode temperature might prolong the life of the tube (though from what I found on the first tube, it was phosphor burning and not cathode emission reduction that was causing the dimming).
:
:...So I went on to use the radio extensively to listen to my music, with the eye tube in the 'open' position, as I was only using the radio's amplifier and not the RF section, so no station was tuned in. Then, after extensive use I pulled the eye tube and tested it in both the open and closed positions. The small pie wedge section was noticeably brighter than the larger normally illuminated section, and so none of what I did helped to prolong the life of the phosphor, and, as can be seen, dimming of eye tubes is caused by phosphor burn and not wearing of the cathode. Often you will find barely glowing eye tubes in which the pie wedge section still glows fairly brightly.
:
:....Not sure what can be done to reduce this problem, as the vacuum fluorescent displays in VCRs, microwaves, DVD players, stereos, and even automobiles will display numbers faithfully for years and even decades, but, for some strange reason, the phosphor in magic eye tubes wears out rather quickly. I guess it depends on the phosphor used, as I have an RCA eye tube in my Crosley Super 11 that's been in there for a decade now, with plenty of use, and it's still somewhat visible, but the Russian 6E5C tubes wear out more quickly. Eye tubes in general, though, tend to wear out quickly. It would be nice if they used a phosphor like that used in a VFD or picture tube.
:
:T.
:
You are right about target voltage. Higher voltage means brighter green.
Unlike picture tubes higher filament voltage has ne effect on green for most eye tubes.
Your idea to control electron flow might work. Thomas did this with AC to the target. What if the target was only supplied voltage for 5 or 10% of the time? TVs operate this way. A spot on the screen is hit with electrons only a small portion of the time. Our eye see the screen lit.
Norm
:T,
:Didn't follow your post word for word, but remember the burnt in "Test Patterns" on old TV's, and burnt in traces on O'scopes of yesteryear. Seems the only action req'd to illuminate the target is electron flow, and conversely, the only way to conserve the phosphor, would be to lower or stop that flow. A lower target voltage or lower emissions from the source would accomplish this. It would be appropriate to assume that raising the emissions level or the target voltage would increase brightness, but never having encountered a "Magic Eye", I'm just guessing. As I recall, picture tube rejuvenators of yesteryear, simply raised the heater voltage, without affecting the anode voltage, but increased the brightness. Another idea I haven't tried, would be a small rectifier and DC heaters, with possibly a regulator chip. Although I can't imagine how this might work, I have several "Rare Earth Magnets" from old PC hard drives that I'd gladly send you for an experiment.
:
:marv
:
::A while ago I posted something regarding perhaps extending the life of a magic eye tube by dimming its cathode and feeding it pulsing B voltage.
::
::I changed the eye socket in my Airline 14WG-806A to an octal so that it could receive a 6E5C, which I have plenty of. Upon first restoring the set I used it extensively to listen to music on my laptop (pandora.com). The eye was wired as the original was wired. After a few months of use I removed the eye and tested it on my tube tester. As it was always 'open' due to my not using the radio portion of the set, the small section of the eye was not illuminated during use. On my tester this section was noticeably brighter than the used section, and so it was evident that extensive use wears out the phosphor.
::
::I then added a resistor to the heater circuit to reduce the heater to about 3 volts. I found that 3 volts would still produce a fully bright target on my tube tester. I also connected the B+ connection of the eye directly to one of the radio's rectifier plates instead of its cathode, so that the eye would receive AC instead of filtered DC. Since the tube will only pass current in one direction, it will actually see half wave unfiltered DC (a separate rectifier is unnecessary). I then inserted an unused 6E5C, with even brilliance over its entire target area (with pie section closed). As wired the tube took a bit longer to light up, but still lit to normal brilliance. I wanted to see if a pulsating B voltage and reduced cathode temperature might prolong the life of the tube (though from what I found on the first tube, it was phosphor burning and not cathode emission reduction that was causing the dimming).
::
::...So I went on to use the radio extensively to listen to my music, with the eye tube in the 'open' position, as I was only using the radio's amplifier and not the RF section, so no station was tuned in. Then, after extensive use I pulled the eye tube and tested it in both the open and closed positions. The small pie wedge section was noticeably brighter than the larger normally illuminated section, and so none of what I did helped to prolong the life of the phosphor, and, as can be seen, dimming of eye tubes is caused by phosphor burn and not wearing of the cathode. Often you will find barely glowing eye tubes in which the pie wedge section still glows fairly brightly.
::
::....Not sure what can be done to reduce this problem, as the vacuum fluorescent displays in VCRs, microwaves, DVD players, stereos, and even automobiles will display numbers faithfully for years and even decades, but, for some strange reason, the phosphor in magic eye tubes wears out rather quickly. I guess it depends on the phosphor used, as I have an RCA eye tube in my Crosley Super 11 that's been in there for a decade now, with plenty of use, and it's still somewhat visible, but the Russian 6E5C tubes wear out more quickly. Eye tubes in general, though, tend to wear out quickly. It would be nice if they used a phosphor like that used in a VFD or picture tube.
::
::T.
::
:
:
Regarding heater temp., yes, heater temp has little effect on the brightness of an eye tube. It takes very little current to light an eye tube, and so the cathode is usually not worn out. The phosphor wears out instead. With CRTs the cathode often wears out with or before the phosphor.
T.
marv
:Feeding the eye through some device that would only pass voltage at its peak would accomplish the same effect as the scanning beam in a television. ...Something like a triac would do this. Connecting the eye tube to the AC side of the rectifier and through a triac would allow adjustment of the duty cycle. I'm not sure if the triac would work properly, though, since the eye tube would serve as a rectifier and effectively only allow current to flow one way through the triac. ...Perhaps a silicon controlled rectifier. I'll have to study that more.
:
:Regarding heater temp., yes, heater temp has little effect on the brightness of an eye tube. It takes very little current to light an eye tube, and so the cathode is usually not worn out. The phosphor wears out instead. With CRTs the cathode often wears out with or before the phosphor.
:
:T.
:
T.