A.J. Bassett, Electronic Didjeridoo, Practical Electronics, November 1964 🇬🇧

Post by **modman** » 03 Jul 2023, 18:48

PDF:

Practical-Electronics-1964-11 Electronic Didjeridoo.pdf: (431.19 KiB) Downloaded 25 times

Nevermind Rolf Harris...

The most wacky, but perhaps most interesting project I've come across in electronic magazines: couldn't it be adapted to a freaky guitar effect? It takes a microphone input... so it literally already a sound processing devices. Should replace the GE transistors with SI and make it negative ground, but I have a hard time understanding what the transformers do.

cspar · Post by **cspar** » 04 Jul 2023, 10:12

Nice.

The transformer 1 & 2 are there in the classic passive ring modulator topology that is common among synth modules and has been used in a few guitar pedals too.

The option of using a transformer (3) to generate the modulation frequency isn't too pedal friendly.

Interestingly, I don't remember seeing a GE driven "passive" ring modulator before.

Thanks again Modman.

ppluis0 · Post by **ppluis0** » 04 Jul 2023, 10:37

There is an explanation about ring modulation:

https://en.wikipedia.org/wiki/Ring_modulation

Cheers,
Jose

Ben N · Post by **Ben N** » 04 Jul 2023, 12:45

As cspar says, T1 & T2 are phase splitters for the two inputs to the ring mod; T3 is a weird way to turn mains supply into a 50/60 hz carrier signal. I think most of us here would prefer to build the oscillator for this purpose.