Introducing the Wrongamin, wrong sound generator.

Sunday, February 14th, 2010 | Building Things, Electronics

The Wrongamin is an easy and cheap to build sound maker that I designed to create a range of wrong sounds. From dusty old record crackles to a deep hungry animal growl heard through several out of tune AM radios. 

newborn Wrongamin

a newborn Wrongamin

It uses three LDRs (Light dependent resistors) to change the pitch of three very high frequency oscillators. What is interesting about this machine is that in normal operation we don’t hear the oscillators directly as they are tuned far above the highest sound a human can hear. What makes this instrument audible are the interactions between the three oscillators which project downward into the realm of our perception. Some Theramins operate on a similar principle and this is where the Wrongamin gets its name.

“A Theramin can sound very wrong in the wrong hands, a Wrongamin sounds wrong in everyones hands!”

I have drawn up a schematic for the Wrongamin (click above for full size version). As you can see this is quite a simple circuit. You can build it using just one integrated circuit (40106B or 74C14) 3 x LDRs, 3 x signal diodes, 4 capacitors, and 2 resistors. If you want to get fancy and have more gain to drive a line level input then add one more IC and a hand full of components. (See Wrongamin Pic above for all parts needed).

NOTE: if you want to leave out the amplifier section: connect A (oscillator out) directly to input of the Output Section – easy. I have not actually tested this configuration but I have no reason to believe it won’t work. I included the amp section because I want to boost the signal a lot to drive my sound-card’s line input.

Here is a video of the Wrongamin’s first test…

Hope you enjoy, Let me know if you make one!

Leafcutter John.

Tags: , , , , , , ,

11 Comments to Introducing the Wrongamin, wrong sound generator.

[…] Pour celles et ceux qui aiment la « noise music» . Les schémas pour construire cet OVNI sont ici : […]

February 18, 2010

Sounds like an R2-D2 on crack! I love it

Bipolar Joe
February 18, 2010

Does the type of LDR make a difference? Size or whatever?

Leafcutter John
February 19, 2010

Size makes little difference, but you want LDR’s with a large resistance change between light and dark. I used these cheapies the data sheet says they have a dark resistance of 1M? but i measured it to be much more than this, upwards of 38M?. Don’t worry too much about it though just get a few to play around with.

March 29, 2010

hello leafcutter john
i came to this site through polar bear and enjoy what you do and write here.
thought you might enjoy some diy stuff from switzerland…
all the best, michelle

Leafcutter John
April 25, 2010

Has anyone made one of these yet??? I been rocking out on mine at the recent Polar Bear concerts!

August 30, 2011

Any chance you can do a basic drawn plan? I have no problems with putting it together but I don’t know how to read circuit diagrams.

Leafcutter John
August 30, 2011

Actually this is a combination of drawn and schematic diagram. It’s very easy to learn how to read circuit diagrams or schematics as they are also called. Maybe i’ll cover this at some point but you could start by reading this: Take your time and start simple and build up. There are loads of learning resources on-line, it’s not difficult but you’ll need to learn it some time. I almost forgot this is an interactive applet where circuits are represented schematically – you can change values and look at a huge range of different circuit types – it’s a brilliant way to learn.

September 4, 2011

Cheers for that. Will give it a shot. I’m hoping to put one together before I head out to Athens for a performance with a mop handle, piezo electric transducers and a guitar pedal.This would be useful for creating diversionary textures whilst I fiddle about with parameters on the pedal and Max loops. Will keep you informed.

March 21, 2012

I’ve been looking at the datasheet for the 40106B IC and I see there are 3 more schmitt triggers that you do not connect to anything. Could these be used to add 3 more voices to the instrument? Also why is the cap value for C2 different from C1 and C3?
Your reply will be greatly appreciated :)

Leafcutter John
March 21, 2012

Yep you are correct, you can add more voices. But mixing more than 3 triggers via diodes does not all ways make things sound richer! Experiment, Diodes, Caps, and LDR’s are all quite cheap. You could build a stereo wrongamin using all the schmitt triggers, I bet that would be nice…

C1,C2,C3 along with the LDR’s affect the pitch of the schmitt trigger oscillators, I wanted slightly different pitches for some of the voices so they are different values. You can try different size caps to get different effects. The reason the wrongamin sounds the way it does is because all the oscillators are pitched above the range of human hearing, the diode mixing creates audible interference between the voices. If you increase the cap sizes the pitch gets lower. Try with 1nf 10nf 100nf 1uf and so on, these will all be audible as a single voice. Mixing them will create more synth sounding electronic music sounds.

have fun, J.

Leave a comment

You must be logged in to post a comment.

Social Links


For you YOUTUBE VIDEO pleasure