Garage Fuzz

[jmusser]

I have some metal can 2N2222 trannies, so I'll throw this thing together this weekend, and see what it sounds like. Does it have sort of an Orange Sunshine flavor to it?

[Doug_H]

I guess the key would be to insure that the 'negistor' is operating in 'tunnel mode'. Meaning, it should be drawing current. By varying the supply voltage you should see a change of the voltage at the junction of the emitter and the 2.2k resistor. If it's sitting at the supply rail, it's not running in negistor mode. Your particular 2n2222(a)s may require a larger voltage to start working. The key word there is 'start'. As you need to reach the breakdown voltage to get the thing started before it settles back into negistor-land.

--john

John, I'd have to go back and look at the voltage readings but I'm pretty sure this was operating as a negistor. It was doing the cute sputter-sputter-putt-putt stuff. It just wasn't real loud. One thing I found was I was using the wrong clipping diodes. He calls out 1n4001 and I was using a pair of fast-recovery 1n4007 replacements. Eh... 4001, 4007...Tomayto, tomahto.... I'm guesssing the fwd voltage is still .7 but I found that leaving the diodes out, using LEDs  diode strings and so forth, changing coupling cap values, etc, etc all made -big- differences in output level.

Although I'm not going to build one, this is a fun circuit to experiment with. (Besides, you know I already have a trashy sounding fuzz, haha!! )

Doug

[Paul Marossy]

I have some metal can 2N2222 trannies

So do I.  Hopefully, you can get yours to work.

[PenPen]

Sorry to resurrect an old thread. I just got a big order from Futurlec, along with my order of 2n2222's I also got an extra set of 10 in the transistor value pack, and a new DMM that does HFE and other cool stuff.

Since I haven't gotten enough of my workspace unpacked yet (though I started last night, I should be ready to build again be end-of-week), I decided to test the hFE on these 2N2222's.

They are marked 'CDIL  2N2222A', metal can transistors.

a)First off, will these work here? Is there any way to test with DMM for their negisistor properties?

b)What hFE values work well here? These things seem to vary all over. I have a few between 100-200, many between 200-300, and one that is >300

c)How critical is that 10M feedback resistor? I know for a fact I dont' have on that high. I can search my salvage parts bins, but if I can get away with a lesser value, that would be much easier.