Misadventures in DIY Audio Electronics

[bluewizard]

Off on a side track. Can I regale you with my own misadvantures?

I use to be a would-be guitar player, more 'would' that 'be' though. I had this righteous SG lead guitar amp, transistor pre-amps with plenty of special effects, and rock solid tube power section.

I had been playing one night when the amp just quite working. A little investigation indicated it was fuse in the leg where the push-pull sections joined together. Simple enough to replace.

For the record, the Tube power section had a 600 volt power supply and a huge boat-anchor power transformer.

A friend dropped by, the lights were dim, smoke filled the air, and a few fresh empty beer cans littered the table. I called my friend over to demonstrate the amp and the problem to him. Holding a microphone in one hand, I pointed at the fuse with the other.

"It was that fuse right .....AAAAAAAURGH!!!!"

As I pointed in the dim light, the tip of my finger touched the 600 volt line. Instantly I reacted dropping the microphone which was providing the ground path. I was dazed and confused but alive.

The palm of the hand holding the microphone has a cinder mark where the 600 volts had arced into my skin. 600 volts directly across the heart, and I live to tell the tale.

It was a lesson WELL, though painfully, learned.

steve/bluewizard

[Johnloudb]

No replies? NO REPLIES?

I'm hurt! Literally. It shocked me.

(no just kidding )

Today is the "can it make sound" experiment. I should have results by this evening.

I'm just waiting for listening impressions. I think this is all really interesting though ... I'm certainly looking forward to seeing your results on this plasma speaker.

Maybe, changing the name of the thread to Plasma Speaker would get more attention.

Although, I think people tend to shy away from speakers that produce noxious gas. :B

[Amphiprion]

Well...

1) It does make sound, and it does reproduce tones (being fed with a sine wave generator).
2) It is most definitely NOT high fidelity yet. Don't expect me posting videos or sound clips for a while. It functions OK at low midrange frequencies, but I can't get much above 600Hz.
3) The ozone produced by a two-electrode setup is MUCH less than a single electrode corona discharge. The youtube video guy who said it didn't produce ozone was correct in that it produces much less ozone than a single corona discharge type tweeter. Before I had it dialed in today I was getting simple corona discharge at each electrode before the arc jumped across them, and was making a tremendous amount of slightly sweet slightly astringent smelling ozone.
4) EMI emissions are off the chart.
5) I need a new HV transformer. I MUST get the PWM frequency much much higher.
6) To that end, I need a new drive circuit. Mine won't work well >100KHz.

[---k---]

Pretty cool. The theory of how this makes sound blows my mind.

[digital desire]

I violated the cardinal rule of keeping one hand behind your back when working on an old adcom 555.
Lets just say I am lucky to be writing this. I also managed to weld one of the power supply wires to a screw in the same classy maneuver.
There is a lot of energy stored in those old caps.