Magic Eye tubes help/suggestions - Meter Circuit for FUN

HI Guys,

I have a bunch of Magic Eye Tubes that I would like to utilize for FUN -- mainly I have some EM4 and a bunch of 1629. I know the 1629s need a Voltage doubler for a 12V filament.

What I would like to do is create a meter bridge with these...

Option 1 - a passive unit with just input meter monitor --
Option 2 - a passive unit with Balanced in and outs (to monitors)
Option 3 - a volume control with transformers (to monitors)
just something simple though.

Again this is for Fun... nothing crazy.

I have found these links... but still trying to figure out. Any thoughts? not sure how to Connect everything and what I would Need to make it work

http://www.nostalgiaair.org/References/Articles/TheFlash/Flash04.htm
http://www.vacuumtube.com/eyetubes.htm
http://www.akh.se/tubes/htm/em4.htm
http://www.antiqueradios.com/chrs/journal/eyetube.html
http://www.audiohobbyist.com/projects/magiceye.htm

:grin:

also check these website

http://www.vcomp.co.uk/tech_tips/eye_tube/eye_tubes.htm

http://antiqueradio.org/art/magiceye.gif

http://antiqueradio.org/magiceye.htm

www.hollowstate.netfirms.com/eye2kitmanual.pdf

question could use a magic eye as an opto for a compressor

Cool thanks

for this schematic

http://antiqueradio.org/art/magiceye.gif

What is AVS?

AVS I dunno. Guessing that since magic eyes were used as tunning indicators AVS has something to do with the signal comming off the radio :?

could it mean: Audio/Visual Signal

Since Magic eyes used to be used in TV and Radio it could be right.

seems right to me.

AVC = Automatic Volume Control.

Most radio receivers had a sort of simple compressor circuit utilizing a control voltage derived after the detector. This controlled the gain of the RF stages. The purpose was to keep the volume from blasting you out of your seat when you tuned from weak to strong stations.

[quote author="pucho812"]question could use a magic eye as an opto for a compressor[/quote]

http://www.groupdiy.com/index.php?topic=15024

AHh ... cool NYD!

Conceptually I'm trying to think of how I could do this. Let me know what you think about this mental block diagram -- there are 3 smaller circuits -

1. the actual Magic eye -- something similar to this:


2. the powersupply for the Magic Eye like from NYD One Bottle

3. what if I used a passive summing design (although there is no "summing") -- just RIGHT channel IN and OUT and LEFT channel IN and OUT.

???

Like This:

Two problems: the detector circuit will load your signal on positive excursions, and also only one polarity of the audio signal will cause the tube to indicate.

I recommend adding a buffer in front with a balanced output feeding a fullwave detector. You can do this with a dual-opamp IC--or, if it must be an all-tube proposition, a twin triode.

Also, you do realize that the tube will darken with increasing signal, right? If you want it to brighten instead, you'll need to add a negative grid supply and a different kind of detector circuit.

Something like a 12AX7?

Crap! NYD ..... I'm trying to keep up with you ... but I'm lost

Been hitting the books and Online resources but not having any luck....

[quote author="skipwave"][quote author="pucho812"]question could use a magic eye as an opto for a compressor[/quote]

http://www.groupdiy.com/index.php?topic=15024[/quote]

thanks man :thumb:

I recall PRR's remark that for a 'fun-only' magic eye the rectifier is not needed. Just skip it and connect the grid directly to what you want to monitor.
I tried this succesfully with an EM4.

If you want a more 'relaxed' cloud of light you could add some lowpass filtering to the signal on its way to the magic-eye grid. Adding a simple R & C section doesn't need to load the source too much if you use a high R & low C value.


And in addition, if you don't already have a filtered B+ I recall a remark from someone that you can get away with a barely filtered B+. Again, fun-only, but magic-eyes aren't the preferred devices for precision metering anyway, especially if you're going for 'round types' as the EM4.

You're aware that the EM4 is actually ultracool because of it's dual sensitivies, right ? :wink:

Bye,

Peter