VFD (Vacuum Fluorescent Display) uses...amps, ring mods, etc...anyone try this?

[SpencerPedals]

I was looking at some random crossover distortion projects a while ago and stumbled across this:

http://www.electronicpeasant.com/projects/ringmod/trmod.html

I found some dead DVD players and a VCR last week and have been disassembling them for the usual film and ceramic caps and any random cool stuff that can be plugged into a breadboard, and this time saved the 3 VFDs.  That ring mod uses a mic and isn't really a great setup for a stompbox, but it did get me thinking that they are indeed tubes.  If you do a quick internet search, there are also a bunch of people that use these things for a headphone amplifier as well, reminding me a lot of the 386 based amps (and thus distortions) around this place, not to mention the immediate curiosity of what these things sound like when you saturate them.  So between the micro-reverb microphonics, amplifying, and clipping, it would seem like there is room for playing around...and I was wondering if anyone had done much of that or had tips or tricks for it.

[Taylor]

I've built the Peasant's "ring mod" and though it's a fun device, it's not a ring modulator. It creates a ringing sound which gets lower in pitch the louder you play. Fun though.

I would definitely recommend playing with them, they are fun. But be careful, because you can blow them rather easily by putting too much power into them.

[SpencerPedals]

It sounds cool and if I find another little mic when I'm scavenging parts, I may have to do it. 

What about using one of these as a reverb tank with like a center stage reverb circuit?  They sure as hell would NOT capture the reverb style sound, but if you put one to your ear they are almost constantly doing a synthy ringing thing.  Would a center stage reverb be able to capitalize on that, do you think?

[Taylor]

Here's what mine sounds like. This is built using the instructions on the Peasant's site.

http://ironether.com/vfd-01compressed.mp3

I am playing a bass into it. The "clean" signal is not mixed electronically, it is coming through the microphone that was picking up the VFD.

[foxfire]

what did you use for the power amps if you don't mind me asking?

[Taylor]

I built a little power amp. 8 watts maybe. Don't remember the exact circuit, as this was a few years ago. But there are little power amp designs out there.

A tip: 8 watts was probably too much. I killed 2 of the VFDs. When you hit them a little harder, the wires heat up and stretch out, which gives that detuning sound you hear. Sounds great. Hit it a little harder, and the display actually lights up. Very neat. But once you start lighting it up, you're on the edge of killing it (at least in the case of the particular displays I have, which I got from an Estonian guy on ebay). The wires break and it's then useless. The Peasant told me something around 1 watt would do the job, though you might lose the "envelope detuning" at this level.

[foxfire]

cool thanks, here i was thinking i could get by with an LPB...

[foxfire]

i've got a bunch of old radios so i'll see bout just snagging an amp out of one of them to keep in the spirit of of the project...

[SpencerPedals]

That sounds really cool...even better than the other clips I've heard.  Don't you think a stage center (or similar) reverb setup would work better because it would eliminate the microphone part of it, and thus all of the bad things that could come with it from unwanted background noises, vibrations, etc?  I've never had to deal with reverb things yet, but from what I understand it's just long springs with transducers that send signal through...and I don't think you'd need a transducer as these ones are just tiny wires and not large springs...or is that not a correct assumption?  Also, I think probably running post-vfd sound through a .001 uF cap at some point would be a good idea as that sounds like it could probably be harsh on the ears at times.

[Taylor]

I don't think you can do without a microphone. I don't really understand the mechanism through which the wires are vibrated, but I don't believe the VFD has any way to naturally turn the vibration back into an electrical signal. It's possible to soundproof it - I think that might be the best you can do. But I could very well be wrong.

[SpencerPedals]

I don't think the VFD has a way to turn it back either, I was relying on the reverb unit to do that.  Probably best results would be by running the "to reverb" and "from reverb" to cathode connections at opposite ends of the VFD, as shown on the Peasant's site. 

[Taylor]

In a reverb unit, the conversion from electrical signal to vibration and back is done in the tank. A spring tank has little transducers at each end of the string, which do the work. So the circuit has no facility for turning the vibration into a signal.

[SpencerPedals]

Ah, right.  Thanks.  For some reason I was thinking the transducers were there for amplification and not conversion.  So essentially a small transducer would be needed to get that all to work out.  Headphone speakers or something similar, possibly? 

[Taylor]

As a pickup? Using headphone speakers to pick up the vibration would work, but it would just be a microphone, which I think you're trying to do away with. Why not use a little electret microphone capsule which is designed to do the job in that case?

I suspect a guitar pickup would also work, since it's basically like little guitar strings vibrating in there. That might be the ticket for you if you want to do away with microphonics.

[SpencerPedals]

Haha yeah after I posted that I was getting ready for bed and was like "wait...I'm right back where I started".  The guitar pickup idea is a good one, though.