Thing Modulator-stopping oscillations with LM567?

[loss1234]

Due to the LMC567 being hard to find (regularly out of stock) I built a Thing Modulator with an lm567.

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


however it oscillates all the time when I am not playing, and not in a good way. I assume this is because I am using a non-cmos version of the chip. What I am wondering is if there is a way to reduce these oscillations while still using a lm567.

or even if anyone knows where to get 4 or 5 lmc567's without having to wait for factory lead time,etc.

thanks a lot

[Dragonfly]

I typed "Thing Modulator" and "oscillation" into the engine here on the site and found....

http://www.diystompboxes.com/smfforum/index.php?topic=33308.msg294981#msg294981

I got the LM567 to work (in a way, anyway) by using the Thing Modulator schem minus the RC network on the power pin (like the Noise 567), and an LDR in place of the TM's 10k, next to the Frequency pot, which I kept at 100k. To quote Tim E :
"with the desire to make the thing shut up when I'm not playing, I found that using both a LMC567...and a 100k/100uF RC network on the power pin go a long way in suppressing the onboard oscillator..."
reading that, I surmised that the 100k/100uF was there just for the CMOS version and built mine like the Noise 567, without the RC network. I also used the cap values from the Thing Modulator (.1uF all round instead of 10uF and 22nF) ...er...for no real reason except that it would be easier to not put them in all the wrong places. The result is a hilarious collection of dirty ring mod, strange atonal fuzzes and quick decay bong/clang/crashing noises, and the worst/best broken speaker/amp/everything-WTF-noise I've ever produced when hitting more than one string. Oh, did I mention the flat out oscillation at some point of the pot arc? Not that useful, but fun all the same. Yes, it ticks through everything, but if I'm not going to stomp on it, I just pull the (DC) power plug.

If I understand your question correctly, that "ticking" is the result of the LMC567's internal oscillator spitting out a sloppy rectangle wave. And sloppy modulation. My guess is that there's probably not much that can be done about it. Real ring/balanced modulators often use a triangle or sine wave oscillator for much cleaner sound down into sub audio frequenies. In the case of the Thing Modulator, simplicity dictates the all-in-one chip design utilizing with the internal oscillator.

I know of no mod to counter the effect.

http://www.diystompboxes.com/smfforum/index.php?topic=56163.0

If so, some bleedthrough might be tamed by fiddling with the RC power bypass circuit. The resistor and capacitor I specify are unusually large, which seems to do some voodoo that otherwise might not be done.

Some bleedthrough may be noticable when the circuit is bypassed, as the oscillator runs free in the background, and with true bypass scheme, the raw signal may remain at high impedance. The solution for this problem may be a buffered bypass.

http://www.diystompboxes.com/smfforum/index.php?topic=52297.0

Anyway, I built one a while ago with the plain LM567 chip, and fiddled with it a while to see if I could quieten it down without much luck. Then again, it's not really the ring mod sound I play with - it's the other weirder videogame noises you can get at the other end of the pot's rotation. There's atonal synthy sounds, tones that go down as you go up the fretboard, no note at all (still trying to work out how to use that feature...) and for a bit more noisy fun I put an LDR in line with the pot like the Christian's Noise 567, that the Thing Modulator was derived from. By varying the amount of light hitting the LDR, you can get a wah-like range of tones. Twiddle the knob, fiddle the LDR. Yeeeha

http://www.diystompboxes.com/smfforum/index.php?topic=46199.0

I had a minor problem with the Thing mod, and found I had to mirror the layout I used. I changed the 100k frequenzie pot for a 500k pot, since I liked the ticking, and it did wonders in a feedbackloop.

http://www.diystompboxes.com/smfforum/index.php?topic=19214.0

It works great for me. Double check your wiring and connections. Make sure your using the specified LMC567 chip and not the regular LM567.

Yes, the LMC567 is absolutely necessary if you want the circuit to behave. That includes a reasonable amount of carrier rejection.

The more common LM567 may not even work with the 100k resistor in series with the power pin, as it's much more of a power hog than the LMC567.

Keep in mind that this is no Blue Ringer. The internal oscillator is fairly limited in range and tone. There's no wet/dry mixing. Carrier rejection is fairly decent considering the simplicity. But any high gain effect after the device will audibly amplify the carrier to possibly annoying levels.

There were a LOT more threads...

The function here works great, you just have to be willing to use it. 

[loss1234]

sorry

i usually do use the search function for most stuff (which is why i rarely post)

i got lazy

please forgive me

[Dragonfly]

sorry

i usually do use the search function for most stuff (which is why i rarely post)

i got lazy

please forgive me

not a problem... hopefully my post helped you find your answer.

[blackieNYC]

Digging up an old one, but I've made some promising changes to the thing modulator, or the Harsh modulator at beavis, more specifically:http://www.beavisaudio.com/library/567/567.htm
I have an LM567C.  Which is NOT the cmos LMC567.  Whichever - the oscillator leaked.  And I got rid of it with a couple small steps
1. At pin 4, the power pin, you get a large oscillator waveform. I did two things with this - a 500 ohm resistor (big Rs as shown in the Escobedo drawing just shut the thing down) in series from 9v to pin 4, and a 220uf cap to ground on pin 4.  That filters a lot but there's still some left.  And I believe it's out of phase with the output.  And that means
2. A blend trimmer pot.  100KB, one leg to a .47u cap on pin 4 picking up the out of phase garbage, and one leg to a .1 cap from the output at pin 1.  As you gradually introduce pin4 audio to pin1, the carrier goes down further in volume relative to the output audio, which also attenuates but not as quickly.  I could be wrong about the phase, but it works like this. Don't use this trimmer to get rid of it completely, your output level will get too low.
3. Get rid of the 10k pot between pins 5 and 8.   Replace it with a wire. Leave the .047 cap there between them. Ground pin 8.  Pin 8 has the oscillator on it at 5v. I don't seem to be drawing any extra current - heat wise anyway. You can add a switch where the wire is but it will bring back a little of the oscillator.  But you've gotten rid of so much of it it is tolerable.  It gives a 2nd color to the modulation.  With the pot, it seems either on or off.  This is not the 100k frequency pot mind you.  That's a keeper- great range of sounds. Or skip the switch and leave the cap from 5 to 8, and wire 8 to ground. No oscillator.
Maybe reverse steps 2 and 3 for efficiency's sake.
4. series resistor on input. Start off with a 100k pot.

I'll put up a messy schematic only after I've boxed this up and it still works. But if you are considering the easiest faux ring mod in the world, this seems to be the answer.
So was it Tim Escobedo or some other nut that ripped this out of a board at the Ma Bell Central Office and said "hmm, I wonder what would happen if..."   Thank you sir.  
And, I wonder why I build anything that isn't from the Escobedo snippets.