I wounder if anyone has a simple circuit for testing magic eyes.
i can test them on my taylor 45d but they dont glow.
what i envisage is box with say 4 valve holders one for each of the common eyes
this is to save on any complex switching.
i think it will need app 180 volt ht 6.3 volt for heaters and a varible 0 to -20 volts for the controle grid.
has any one built such a device?
rob t
(09-08-2012, 07:22 PM)tiv48 Wrote: [ -> ]I wounder if anyone has a simple circuit for testing magic eyes.
i can test them on my taylor 45d but they dont glow.
what i envisage is box with say 4 valve holders one for each of the common eyes
this is to save on any complex switching.
i think it will need app 180 volt ht 6.3 volt for heaters and a varible 0 to -20 volts for the controle grid.
has any one built such a device?
rob t
Nope, not built one but I am guessing you are on the right lines ie: anode voltages same as what you would typicaly find in a receiver and grid voltage to simulate typical min and max AGC swing, I would have thought that most characteristics for octal valves would be similar (ish) I do not know about B9A etc, sounds like a good project to do, maybe a switched output to a test point for setting up purposes, just kicking a few ideas around.
Lawrence.
There is a challenge Rob!
Sounds like a plan.....
cheers Mark
any ideas gratefully recived .
rob t
Hi RobT, do you need to do ma/v, shorts, gas test/grid current etc or just a target display go/no go, if it's just a go/no go you might get away with one set of fixed anode resistors etc for most of the common ones. it would keep it simple. Also if you wanted expand the number of valve types without switching you could easily knock up a seperate plugin to fit any existing skts it might have.
Lawrence.
Oh dear, you're giving me ideas and they don't involve an HT transformer.
- Joe
hi lawrence its just to get a display all the res can be checked on my taylor.
the reason for this is that i bought a load of em80/em84/em87. from the Ukraine they were used but meant to be ok .i tested 10 all passed,but when i tried one in a set
it was dim.i tried two more and they were ok.so just a method of checking the target brightness.
rob t
(09-08-2012, 08:08 PM)tiv48 Wrote: [ -> ]hi lawrence its just to get a display all the res can be checked on my taylor.
the reason for this is that i bought a load of em80/em84/em87. from the Ukraine they were used but meant to be ok .i tested 10 all passed,but when i tried one in a set
it was dim.i tried two more and they were ok.so just a method of checking the target brightness.
rob t
Hi robT
They can be a pain those magic eyes, insofar as some are hard to obtain, I usually check all the voltages and then start trying other things in the vain hope that some how the display will get better, in most cases if the grid voltage is swinging enough and all the anode and heater voltages are more or less ok then the said item has had it, at least a simple tester will give you a definitive answer.
Good luck with the project.
Lawrence.
(09-08-2012, 08:16 PM)Joe Wrote: [ -> ]There may be something in this: http://www.b-kainka.de/bastel80.htm
- Joe
Enjoyed reading that Joe.
Another example of using the circuitry from a disposable flash camera to generate 250V HT from 6V.
Could also be used for a zener diode tester or cap leakage tester, where high voltage/low current is all that's required.
Obviously an inventive guy, with a wry sense of humour too. I liked these quotes produced by google translate:
Before the last error found, pass often laborious hours.
We all know about that don't we - how we suffer for our art!
The magic eye is best done in the dark with a glass of wine. Thanks to the battery operation, it can be used on warm summer nights in the garden. The green lights and gentle vibrations relax the viewer quickly and effectively. Even after ten minutes, away all the heavy thoughts. After another ten minutes, the viewer falls into a trance, with no guarantee can be assumed that he also wakes up.
Brings a new slant to the saying 'happiness is a warm dropper' - 'happiness is a nocturnal glass of wine, a soporific inducing magice eye and a catatonic trance'
