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Organ donor beats

and pedals

his project recycles the guts of an old 1970s

electronic organ into two standalone instruments:

a MIDI controller, and a rhythm-generating box.

An old organ was starting to fail, but the pedals and

beats both worked and were my favourite parts of the

instrument. Bass pedals are always useful – you can

sing, play ukulele/guitar/piano, and accompany all that with bass, all

by yourself! And the rhythm chip from the organ was fantastic: for

some reason, it was designed so that you can superimpose beats.

So if you have, say, ‘bossa nova’ playing, and also put down the

‘tango’ switch, it doesn’t stop playing bossa nova, it puts the two

beats on top of each other.

There are three PCBs inside the beats box: one is from the

original organ; it’s large, single-sided, and hand-traced. You can hold

it up to the light and see all the copper connections through it! The

other two PCBs are a tube amp and power supply. I added the tube

amp specifically (rather than just a solid-state amp) to put some

subtle ‘stereo’ action in the audio; the beat generator circuit outputs

a mono signal, but putting it through the subtle distortion of the

tube means that the two sides of the signal are slightly different in a

pleasing way. Also of course, having the tube sticking up out of the

top of the build looks cool!

The pedals are running a Teensy 3.2 on a custom PCB – my first

one! I didn’t do any fancy multiplexing, I just have one pedal per

pin. No other components, except for some resistors and a status

LED. Both projects involved a fair bit of woodworking, but Beats

was my first time working with hardwood. Not only that, but the

design is curved in all three dimensions, so in many cases I couldn’t

easily clamp it down to work on it! That really made me appreciate

why so many things are built into rectangular boxes – but all in all

I’m glad I did an unusual shape, because I’m very happy with the

way it looks and feels.

T

By Charlie Williams c.harl.ie

Right

Charlie made the

Beats housing hand-

held, curved like an

mbira or djembe