Resuscitated Nurse Quacky

[petemoore]

She's been enlisted over a year now, looks like she's ready for work finally.
 I had gotten some interesting uses from her, limited range on the neck...cool.
 TL082..what I'd been running "Till tonight
 5532...found this one to be 'gakky' in NQ, overloaded or something bad
 4558...this is the one for mine. The performance of NQ improved markedly, this one stayed in there. Circuit is the most opamp sensative I have.
 This is where the good part is [if you've read these type-ings before skip to next thread]...
 I started swapping transistors and realized much wider range of sweep and tone [each transistor covering a segment of the range, some much wider than others].
 3904...was in there the whole time :shock:
 BC109...thick sweep tone, interesting, decent sweep
 2n5089...the overall sound went to higher range, out of the capacity of the sweep limit knob [I think that's what it is], wild envelope effects, crazy sweeps, profoundly psychadelic [phaze 90 beforeand Fuzz Obsidian in some of these tests].
 NTE123...is still in there, this is the only [of about 10] transistor that really tuned in a nice regular quack, it's still in there. When combined with some amp feedback to keep the sustain/amplitude to the envelope follower, slight to pronounced vocal quality sweeps can be had by just bending the strings at differing rates/stops/plucks...quite expressive. Sounded good for rythms and leads.
 Transistor sensativity is exceptionally high, the 3904 offered poor performance in the circuit, and many others were also out of the pocket. I'm not recommending types as much as offering possibles %age wise any NPN Si seemed to get it working. It would be interesting to try a trimpot resistor bias mod [if necessary] socket for Ge's in there, just for kicks to see if they'd affect the envelope in some interesting way. I suppose it's just a matter of gain, but there are probably differences in frequency/gain between transistors that illicit the different responses I heard from the circuit.

[MartyMart]

Transistors are  a P.I.T.A  !!!
I had to try soooooo...... many J201's to get my English channel to work properly, after re-building the circuit twice, thinking that I'd got something wrong !! and I had problems with both Buzz Box's due to the differences in 2N3904's performance.
I have a newer DMM with a hfe checker on it, I guess its time to "sort out" the decent Trannies   :?  :?  :roll:

Marty.

[Mark Hammer]

If you have the means to replace the transistor with an LED/LDR combo, do it.  The circuit will work fine since all the transistor is doing is mimicking a variable resistance to ground.  

Use of an LDR will also reduce the envelope ripple a bit, something which virtually every DQ derivative needs, unless you opt for the long-decay option.

The other advantage of the LDR to ground option is that you can easily tinker with the frequency range by means of series and/or parallel resistors in tandem with the LDR.  Tnikering with the transistor is a little trickier.

[erix]

If you have the means to replace the transistor with an LED/LDR combo, do it.  The circuit will work fine since all the transistor is doing is mimicking a variable resistance to ground.

Mmmm... This would be a fun place for the Tone God's latest Vanishing Point....

I'm building one of these right now - wish I saw this before I did my layout!

At least I can sub in some different trannys.

erix

[jmusser]

This circuit looks like it might be worth doing a switch that takes in and out transistor preferences. I had heard about that on another thread the other day, and wanted to know a simple way to do it.

[petemoore]

This circuit looks like it might be worth doing a switch that takes in and out transistor preferences. I had heard about that on another thread the other day, and wanted to know a simple way to do it.

I was just about to post that, a 3pdt will switch between two transistors, I wonder if a dpdt could do it...like leave the emitter connection or something.

[jmusser]

I wouldn't see why a DPDT wouldn't do it. As long as you're basically putting one of the two transistors out of business, leaving the emitter connected, would mean Q1 would be dead, or Q2 would when you selected either or. If nobody says "I'm the one", then I'll draw it up, because I know it would be useful.