Gargletron not gargling (chip question)

[jmusser]

I put some time in on Tim's Gargletron the past couple days, and still can't get it to give me any vowels sounds. I am getting amplification that I can control with the 100k pot, and I can change the amplification tone with the 10k pot, but that's about it. According to an op amp sheet I got off the forum for the TL062, I have U1a with the input on pin 2, VR on pin 3, and output on pin 1. U1b input on pin 6, Vr on pin 5, and output on pin 7. Pin 4 is ground, and Pin 8 is 9V. Is that correct?

[niftydog]

they are the correct pins, but the diagram doesn't actually specify which input is inverting and which is non-inverting. However, what you have assumed makes sence to me.

Have you checked the biasing of the transistor and op amps? Are you positive that you have the correct capacitor values? Such small caps are often poorly marked and they're easy to mix up.

[jmusser]

I will check them again to be sure, but I usually have a magnifying glass with me every time I use the little ceramics. I'm doing this from memory, but I believe there were a couple 680 pico farads on there, and they read 681, and the .1s read 104, so I believe they are correct. I believe 103 is .01 and 102 is .001 mf, where the decimal point moves to the left, and the zeros go to the right (true?). Now, that I'm thinking about it, if what I'm thinking of as 680 pico farad actually said 680 instead of 681, would it really be 680, or 68? That one I can't remember. I had that stupid chip wired both ways, and the way I have it now, is the only way I got anything through the circuit at all. There wasn't any + or - designations on the schematic as you say, so I used his "Phuncgnosis" circuit for a reference. Maybe Tim will see this and clear it up for us. I'm not sure how to check bias or what that really means, but I'm guessing that it means working voltage parameters. I've heard that batted around a lot, especially for germanium transistors, but it seemed like you'd have to have a doctorate in physics or a Ouija board to figure it out.

[Doug_H]

;lkj

[Nasse]

Now if anyone has any ideas on controlling this thing with a variable resistor

Don´t see why this could not be controlled by two LDR´s. In theory it should work but finding right circuit for nice response... I have seen some synth/vca circuits that work something like for one control voltage one output goes down when the other output goes up

[Doug_H]

;lkj

[Nasse]

:oops: :lol:

[jmusser]

Wow, that's going the extra mile to simulate the circuit! There's a sound sample of this thing, so unless the schematic was transcribed wrong, then the thing ought to work. I brought the schematic with me to work tonight, and somewhere in the wee hours of the morning, I ought to get a chance to go back through it. The last time I fought with the Phuncgnosis, I just went ahead and drew out an Easy Build schematic by hand, so I could have something simpler to go through, plus make it easier for others if they want it. A couple guys have asked for it. Tim's circuits look simple because they are so small, but man are they condensed and tricky to wire!I need to get my Easy Builds going again. My computer crashed a long time ago, and I would have to start from scratch doing the symbols all over again in Paint, but once you get them done once, you always have them to cut and paste from, from that day forward. So, what would the LDR configuration do for you in this circuit and is the Gargler in essence what you're looking for? Hey, thanks again for your input BTW.

[Doug_H]

;lkj

[Doug_H]

;lkj

[jmusser]

Well, I found what I hope is the problem during my lunch hour. There is a pair of 50K resistors in this circuit. One I made up out of two 100Ks in parallel, and the other one was supposed to be a 50K. It ends up that it's a 51K, and I figure in this circuit these two would have to be pretty evenly matched. I will replace it when I get home tonight since it's a quicky exchange, an see if that does the trick. Otherwise, it's back to the drawing board, because I have found no wiring errors. The Octup is still and inigma. The 10Ks in there might be 1Ks, and the 2.2K might be a 22K. I need to get it under some good light and see if that's what I've done. The 3rd band on these is real thin, and it's really hard to make out. I hope that's it, because I can't find any wiring errors or transistor pinout errors.

[RickL]

I built mine (both of them) using standard value resistors and they work fine. 47k for 50k, 4.7M for 5M. Don't worry too much about exact values, that's not the problem.

I really posted to brag a bit about an experiment I tried that worked pretty good. I wired the two Gargletrons I built in parallel, mixing the two outputs passively through 10k resistors. I used a 10k dual pot to control the frequency of both at the same time and wired one with a dpdt switch so I could switch the direction that the frequency moves when the pot is turned (one gargles up while the other gargles down).

The Gargletron is great by itself but two in parallel or anti-parallel is even better. It sounds even more vocal than one by itself and the original sound can be achieved by just turning the volume down on one of them.

As I'm typing I think I should add another switch and pot so I can sweep one while the other is at some fixed position. I'll try it and report back.

[puretube]

http://www.geocities.com/tpe123/folkurban/fuzz/gargletron.gif

+/- 10% in component values very probably won`t turn this circuit into a "no-go"...

[RickL]

On the off chance that someone is interested ... I did the mod I described above and it sounds pretty good. Sweeping one Gargle against another fixed one isn't as interesting as sweeping two against each other but it's certainly worth a dpdt and a pot. I suspect the principle is the same as what MXR did in the Phase 100 with swept phasing against fixed notches.

Slightly off topic  I again reinforced to myself to never give up on a project. I built a 4ms (then 3ms) Phaseur at least two years ago and never could get it to work right. It would phase for a while then gradually the wet sound would die out. I could reactivate it for a while by quickly shorting the battery.

Last week I built another one from scratch figuring if I could get it working I could use it to trouble shoot the old one. Well of course the new one didn't work either, this time no sound at all. I looked back at the old one and realized that I had soldered one of the jumpers to the wrong pin on one of the opamps. I changed the jumper and it works just fine now.

I've looked at that board dozens of times over the last couple of years and  didn't notice it! Flush with success I quickly found an incomplete trace on the new board and now it works too.

If you can't figure out why something doesn't work after the first couple of tries, put it away and go back to it later (although perhaps two years is a bit excessive    ).[/i]