I couldn’t control myself. After seeing these cool demos of the Magick Eye tube, (a tube commonly used as a tuning indicator in old radios) I had to try them out in my amps. So I plopped together a quick video to see the dramatic and cool visual effect. I will probably tweak some values but overall I am very happy with the visual effect.
The circuit is nothing complicated. All you need is one of the many Magick Eye tubes existent out there, with many different beam patterns, that might need a slightly different pin-out connection, but all of them work in a main common way – it taps in the path of the signal level of roughly 10 to 25 Volts (depends on the type of tube used), and a high DC voltage of something between 200 to 250 (B+).
I used a Russian EM80/6BR5 I scored off Ebay. The EM80 tube has a “U” shaped fluorescent target and two rods connected to the anode, producing two angled shadows on the edge triggered by the control voltage (input signal).
The schematic I used is the one below, posted by Michael on the 18watt site.
I tapped the control voltage (signal) off one of the plates of the EL 84 tubes, and got the high voltage of about 250v off one of the filter caps.
Check this video out of how cool this can be!
Related posts
Gabi, you definitely put the cherry on the cake’s icing with that one. It may be about the most frivolous mod that can possibly be done, but it’s sure way more cool than a silly biteme lamp. ROFLMAO I’ve got a Hammond cage top chassis that I’m now tempted to put one in just for the hallibut.
Thanks for posting that!
Gil…
This is a fist time I hear of those, and I must say they’re incredible
I want to incorporate one of these onto my amp, but I have a stupid question for you. I see where I get the 250v off of B+, but which pin of my EL84 do I get the signal? Also, the heater wires need to be hooked up, right? Sorry for the questions, but I’m still learning. Thanks in advance.
Thanks folks!
Mike – usually you can tap for signal anywhere off the EL84 anode (one of the tubes). That would be pin 7 of any of the EL84 tubes.
Forgot to mention – yes hook up the heaters to the 6.3vac connection.
SUPER NICE it`s realy cool to add a magic eye tube in a guitar amp.
Thank you for this great thing.
Greezz from Holland
Awesome
I salvaged one from a junkyard the other day and I’ve been looking for a schematic to make ti light 
I’m interested in, can it be driven by an audio output of a PC or from a regular amp.?
Ted – That’s what I am planning to add with my future amp builds. I think there’s nothing more cooler than that!
Aleks – It should be driven off any audio circuit. The only thing is to get the signal to a decent level & impedance accepted by the input of the magic eye tube.
One more thing, the value of the capacitors is 0.1 micro or pico farads ?
Aleks, it is a 0.1 micro farad.
Hello, I’m a bit late in seeing this but thank you for posting. I will add one of these in my next build as I already have a few purchased recently. I would like to point out that I am planning on using the 8 ohm tap at the speaker jack like taken here for negative feedback when used. Lower voltage & ratings for components instead of HT worries and with same parts count. Cheers!
Very good idea! Curious of the final result – I am just concerned if this will affect tone in any way.