Here’s a little video from Julian Ilett on how to use this circuit to quickly burn out a whole bunch of transistors:
4 Likes
In his video Sam talks about how it’s tough to use a 2n3904 with a synth power supply because it needs >12V to avalanche. But is there any reason not to connect this circuit between +12V and -12V rather than +18V (or whatever) and ground? A bonus to doing that is if you take the output from R2 to ground then the DC offset is eliminated or at least greatly reduced. I’ve done this and it seems to work, but is there some pitfall I’m not thinking of?
4 Likes
Lego breadboards! I didn’t know that was a thing.
3 Likes
Ah damn I was hoping to add this to a 12v eurorack power supply for a super simple synth
1 Like
LEGO + SNYTH’s = heaven
1 Like
SS9018 transistors only need 8v for the reverse avalanche effect. Perfect for a 9v battery or a +12v eurorack supply. Give it a go!
4 Likes
just reminds me of watching sifi on the tv back in the 60’s / 70’s . playing with the legos watching startrek. and all the other sifi ,thriller stuff with their sound tracks that were using Moog’s , etc. and other tape tricks to make awesome background sound effects / tracks .
1 Like
Three of my favorite moments being a dad:
- 9 year old eldest daughter asking for a drumkit for her birthday!
- youngest daughter aged 5 stating all she wants for Christmas was her own roll of sealotape .
- youngest aged 9 scaring the crap out of me with an intruder alarm made from Lego mindscapes. (Lego is so much fun and worth every scar on my feet)
4 Likes
Or, as I was saying above, try putting it between +12V and -12V — unless that’s a bad idea for some reason I haven’t seen and no one else has brought up!
3 Likes
Worth a go. No obvious reason springs to mind. The worst that will happen is you don’t get the oscillation. Good call @analogoutput
1 Like
Oh, it does work. Post must be at least 20 characters.
3 Likes
Brilliant! Drone time! (20 characters indeed)
1 Like
Trying with 18v on a bread board now, get a flickering LED for a second or two then it does off. No sound at all.
Oops had the cap around the wrong way, now get consistent LED when adjusting the pot, still no sound. Maybe need to try different headphone, these are some crappy airplane ones.
1 Like
Success with better headphones! Now wondering what is wrong with my strip board layout
1 Like
Success!! Moved the cap back to ground and got the strip board working on 18v thanks for your help folks, I might try the other transistor on 12v next
2 Likes
Same with 12v from the power supply, still kinda quiet straight to headphones.
2 Likes
Thanks for the report! Interesting to know it’s quieter but I suppose it makes sense that the amplitude would be related to the breakdown voltage.
Anyone looked at ranges on these things? With 24V (±12V) on a 2N3904 with a 10µF cap I find I can raise the potentiometer up to about 3k before oscillation stops. Counting the fixed resistor that’s 1k to 4k from which I’d expect about 2 octaves’ range and I think that’s about what I hear.
3 Likes
