now hold that blinking light up to the photoresistor, and you've got a tremolo circuit.'[/i]

Just to clarify, these are two seperate circuits that create a tremolo like effect when used in conjunction with each other? Is there any way to have this on one circuit? Also, are veroboards ok to use in effects pedals or would i need to use PCB?
Thanks a lot

yep, two different circuits. The second one with the 555 chip, is just the first simple oscillator circuit that came up when i googled. You can use pretty much any sort of blinking light circuit.

Honestly I'm a bit of a caveman myself when it comes to electronics, but i've built a few rather nice feedback loopers, and been messing around with tremolo ideas quite a bit for about a year now.

First off, I would suggest that you experiment heavily with sending your input signal to ground via photoresistor.
this is your experiment circuit:


pretty simple eh? Just shine a light on that photo resistor while you have an audio signal running through the circuit, and the volume should drop. cover up the photoresistor so its in the dark, and the signal is loud again.

but you want to control that volume drop automatically, in tremolo fashion, so you'll want this: http://www.electronicecircuits.com/electronic-circuits/555-variable-frequency-square-wave-generator (or something like it) hook a light , most likely an LED up to the output of that diagram. Positive end of the LED to output, negative end to ground, of course. Then you get a fancy blinking light. Remember to experiment with different size caps and resistors in that circuit to get the speed you are looking.

now hold that blinking light up to the photoresistor, and you've got a tremolo circuit.

Parts:
I would suggest you look on ebay for 555 timers, i've found some good prices there.

photoresistors, LEDs, optocouplers: "If you want to use a separate photocell and LED, try a Silonex NSL-5542, my SKU 2506. This is known to work with a clear, hi-brightness LED, SKU 2302. If you want a complete photocell/LED assembly at a reasonable price, try SKU 2510M, type "F". That's known to work in the Tremulus Lune and the Tremulous Bear." that is the response i got from the guy at: http://www.smallbearelec.com/servlet/StoreFront who has been very very helpful to me whenever i've emailed him with questions.

Other parts, i would purchase at http://www.mouser.com/ they tend to have pretty good prices on most things.

as for doing such things within a feedback looper. This is pretty much the same as volume control in a feedback loop, which is very close to what i've been asking about lately, and been told that its been answered several times on this board. I honestly have been a bit lazy about looking it up, but it involves using buffer circuitry, and well, like i said i've been a bit lazy looking into that, so let me know what you find after looking here: http://experimentalistsanonymous.com/board/index.php?topic=2855.0

and here: http://experimentalistsanonymous.com/board/index.php?topic=2883.0

I am not sure you quite understand me. (although I think your answer is probably the same either way) I think my intention may be even simpler than you think. All I am looking for is to create a circuit which can act as a feedback looper OR a wet/dry signal loop for an external effects pedal. I am not looking to blend the fedback signal with the dry signal.

I've added a newer design below, which might clear things up a bit (or possibly confuse them more) The circuit on the black background is just the exact same circuit, but with the little "housefly" fuzz circuitry detailed.

the purple line (not the pink/magenta one!) which includes sw3 (and the switching pot next to it) is what I am concerned about. It is a simple feedback line, until sw3 is closed, and then it becomes a dry signal bypass mixer to the "housefly" circuit, and whatever external fx gets plugged into the send/return jacks. Except that this just doesn't seem to work in my early tests. I did actually read a previous thread: http://experimentalistsanonymous.com/board/index.php?topic=2855.0 shortly after I had posted this one, and put the same question in there, as it is a very similar concept. Someone on that thread suggested putting in a "buffer" which is fine except I am not terribly familiar with building a buffer. So I suspect that what I really need to know is, what's the simplest buffer I can get away with? atm i have access to 386 amplifier ICs and several types of transistors, but not much else along those lines.

oh. I just saw this and realised that my new topic was extremely similar. Not sure if I should delete it and just post here, so for now I'm just gonna post it here, and possibly delete the other tomorrow. (its late and i should not be making any important decisions right now  )

So, I've built a bunch of simple feedback loopers like this:



And I want to turn that feedback loop into a dry signal mixer.

I imagined that all I would have to do is ground the pot(s) (either one or both, or just use a single pot, and ground it) to change it from feedback loop to dry signal mix.

I've tested this out with a simple alligator clips wire on one of my fuzz pedals that has a built in feedback loop circuit with pot, and although it certainly changed the tone of the feedback, it did not stop the feedback, nor did it magically become a dry signal line.

I feel like an ignorant newb even asking, but what am I doing wrong here?

so... buffer. um dumb question, but what would be the best way to do that?

So, I've built a bunch of simple feedback loopers like this:



And I want to turn that feedback loop into a dry signal mixer.

I imagined that all I would have to do is ground the pot(s) (either one or both, or just use a single pot, and ground it) to change it from feedback loop to dry signal mix.

I've tested this out with a simple alligator clips wire on one of my fuzz pedals that has a built in feedback loop circuit with pot, and although it certainly changed the tone of the feedback, it did not stop the feedback, nor did it magically become a dry signal line.

I feel like an ignorant newb even asking, but what am I doing wrong here?

Say, whilst we're on the subject of lm556; I have an issue with the little bastards:

As per this: http://amishrobots.freeforums.org/double-tremolo-t17.html diagram, I have this issue, where one osc control affects the other. That is, when i turn up or down the rate knob for osc #1, the rate of osc #2 slightly changes as well. The only thing i can think that makes sense, is that since they share the same power supply, the dip in available overall current/voltage/whatever changes the other one as well. Except that doesn't actually make sense, now that i think about it, because when i turn one up to a higher freq, the other one goes UP as well. Why the heck do they seem to modulate eachother???

all sorts of things you can do to make it crazy. The Bazz is a really nice, easy circuit to build, like the other guy said, build 2 or 3 or... and such, and run them all in series. At some point you'd probably want to amplify your input signal too. If you're looking for a nice simple circuit to destroy tone and play around with though, I'd suggest a simple ring modulator: http://www.cgs.synth.net/

okay, sorry I know the last post here was like 2007 maybe its a dead topic, but i figure anyone who happens to stumble across this thread really oughta just go here :http://www.cgs.synth.net/modules/cgsrr.html There's a nice parts list and everything. I've built like 8 or 9 of these now. They might sound better if you matched the diodes, but I haven't ever even bothered, and they've all turned out great. Real nasty, like an army of Daleks.

It appears to be a diode ring mixer to me. The diagram is poorly laid out. I'd have to redraw it to make it more sensible to me.

It's designed to take an audio input signal "Input" and an input carrier signal and then mix them. When you "mix" them this way, you should get sum and difference frequencies out (unless the difference is too low).

If you put 3000 hz into input and 5000 hz into carrier, you should get the following frequencies appearing in the output:

- 3000 (original)
- 5000 (original)
- 2000 Hz (5000-3000Hz)
- 8000 Hz (5000+3000Hz)

If instead of a single frequency, you supply "audio" into the input, you can shift the entire audio band up and down by application of the carrier. You normally filter out the upper or lower sideband of interest. 

This appears to be part of an audio ring modulator (the output transformer pretty much rules out RF use, depending upon the transformer).  But to make it useful as an audio ring modulator, you need to add a filter to isolate the product that you're interested in (normally the sum or difference sideband).

Thanks, I was pretty sure i'd laid it out as plain as possible, but yeah, I'd be happy to see your "redraw". Connecting each of the transformers to opposite sides of the circuit means lots of unconnected pathways crossing eachother on the map. I couldn't think of any less confusing way to lay it out.
So yeah, it is a basic diode ring mod, to which I've injected a basic "bazz fuss" circuit in place of each of the 4 diodes. Having now actually built the circuit, I find that it doesn't seem to do much other than mix 2 audio signals and amplify them a bit. My ears may not be the best, but i could hear no evidence of any sum/difference freqs; perhaps if I could filter as you mention. Any suggestions as to how i would do that?
For the time being I've pretty much abandoned this project in favour of an entirely different circuit which has given me much more interesting results.

It looks like a flux capacitor!

I knew someone was going to say that.

so i built it. It doesn't really do much. Seems to take two input signals and combine them, spit them out of the output, without actually doing anything interesting to either. Maybe it amplifies them. So basically just a sort of audio mixer. Maybe if i changed a few things around the right way it might do more, but i've found a far more interesting circuit to play with, so i'm pretty much abandoning this project for now.

I should mention that I really don't know wtf I'm doing. I've built a couple simple little pedals; ring modulator, feedback looper, bazz fuss, and a nice astable multivibrator. To be honest, I still really have only a sketchy idea as to how even the basic components really work. So with that all in mind, I had this idea. Like I said, I've built a few basic effects, and I'ts made me think alot about how I could make them, well crazier. So, with my very limited knowledge, I finally came up with something. Basically I married a bazz circuit to a simple ring modulator (in my mind) and came up with this, as the offspring:



So, my questions are:

Will this actually work?

What is it likely to do?

Have I put the capacitors in the right places? or do I need to add more diodes somewhere?

I guess what I'm hoping for is some sort of overdriven/fuzzed/amplified ring modulator effect, but I'd settle for pretty much anything that sounds um, "different" i guess. Keeping in mind that my intended use is noise music, can anyone advise me on how to proceed here?

oh, and I'm still trying to sort out which should be "tip" vs ground on all the inputs.

And a simplified version:

not sure what to look for when it comes to "quality" in a soldering iron. The one i'm using right now is a RS adjustable up to 50 watts, seems to wrok ok except that I have to sand the tip a bit after every couple of connections. Is there a certain brand I should look for? I assume Weller would be one?

so where should I go for a good soldering iron?

there, I've modified the pic a bit, in hopes to make it more readable, easier to understand.