Finding Loops/Feedback Loops?

Kefo042 · February 10, 2012, 08:07:32 PM

Hey gang, I'm a long time prowler, first-time poster. First I want to thank the owner and all the members for this vast compendium of knowledge and recorded experience - it is such an asset to budding circuit benders! Now to the less cheesy half of the post:

I was wondering if there was a general approach to finding loops in toys? And what is a feedback loop technically?

Also, (in the case of a toy with a microphone) is there a simple way to send the signal from the speaker of a toy back to it's microphone, creating some kind of feedback effect? I'm not sure if this is considered a feedback loop as well, so correct me if the terminology is off. All information on the subject would be highly appreciated!

Dylan · February 14, 2012, 03:23:51 PM

Usually poking around the power amp chip in a lot of keyboards (especially those with microphones) you'll be able to get some hearty feedback.

Kefo042 · February 17, 2012, 11:32:48 PM

Cool, thanks! I also found these two links quite helpful, in case anyone checks this post for the same information I was seeking: http://www.boyinaband.com/2009/11/what-is-circuit-bending/ (scroll down for looping info) and http://casperelectronics.com/finished-pieces/circuit-bending-tutorial/looping-with-transistors/.

Bogus Noise · February 21, 2012, 01:57:49 AM

Some toys will loop if you send the speaker + signal into points of the keyboard matrix. The sound basically triggers a key when it goes over a certain threshold. Not all toys do it but you get some good effects when you find one, great being able to pitch them up to make a fast oscillating tone!
Others loop when you interrupt the clock in some way, depends on the toy again, but you get some good ones sometimes. I got a good one from the Letter Fun PC, great tones in that, which I'm dying to play with in Kontakt and Alchemy

Audio out to microphone in is a classic feedback bend, people do it on old synths as well, including the circuitbenders.co.uk SH101/MC202 mods.

Kefo042 · February 23, 2012, 05:39:41 AM

Thanks a bunch for the tips, I tried both those bends on an optimus prime voice changer and got some great results! Cheers

Dylan · February 23, 2012, 10:55:32 PM

Quote from: Bogus Noise on February 21, 2012, 01:57:49 AM
Some toys will loop if you send the speaker + signal into points of the keyboard matrix. The sound basically triggers a key when it goes over a certain threshold. Not all toys do it but you get some good effects when you find one, great being able to pitch them up to make a fast oscillating tone!
Others loop when you interrupt the clock in some way, depends on the toy again, but you get some good ones sometimes. I got a good one from the Letter Fun PC, great tones in that, which I'm dying to play with in Kontakt and Alchemy

Audio out to microphone in is a classic feedback bend, people do it on old synths as well, including the circuitbenders.co.uk SH101/MC202 mods.

I never even thought of doing that, now I have something to do this weekend!

Bogus Noise · February 24, 2012, 02:01:52 AM

Not sure which particular nugget you're referring to, but enjoy

Dylan · February 24, 2012, 04:16:16 AM

Quote from: Bogus Noise on February 21, 2012, 01:57:49 AM
Some toys will loop if you send the speaker + signal into points of the keyboard matrix.

Uh, mainly that one

Bogus Noise · February 24, 2012, 08:56:15 PM

Ah, cool

Not all will do it, but some cheaper VTechs do, including the phones and some models of the Groovy Tunes. Frustratingly, I have a bunch more Groovy Tunes that won't do it, but all of them use the same board etc... I've got very close to finding out how to change the ones that don't to ones that do, but can't post tips on that till it makes sense.

The Yamaha PSS7 does some pretty silly stuff too. I have a wicked bend of that but no video yet as there's something I need to hone on it before people can see the end result!

deathbender · May 01, 2012, 01:55:21 AM

Quote from: Bogus Noise on February 24, 2012, 08:56:15 PMThe Yamaha PSS7 does some pretty silly stuff too. I have a wicked bend of that but no video yet as there's something I need to hone on it before people can see the end result!

If you're talking about a feedback loop then try to inject some static hum into the loop though a simple single body contact. Makes the feedback loop freak out completely, giving you even more screeches and whining mess