Category: Electronics

Bass synth, work in progress

I am working on making a bass synth. It will be controlled by some old organ pedals, but currently it just works by adjusting pots.

In the schematics you can see the voltage regulator in the top left. I use 12volt DC in, from an old PC power supply. Which I regulate to 9 volts.

The 4093 contains four NAND gates with Schmidt triggers, and I use two of them. One controls the pitch of the sound, and the other controls the first one, by turning it on and off, so you get kind of an arpeggio. You can also turn that on and off with SW1.

The 4040 is a frequency divider, that is fed the output of the tone oscillator, and then each of the outputs of that is fed into two rotary switches. In that way you can mix together two octaves at the same time, getting a richer sound.

Most of this project was inspired by the book “Handmade electronic music”, by Nicolas Collins.

If you have any questions, or suggestions for improvements, please drop me a line.

Pedals for Ableton Live

For a concert later this year, a friend is gonna use Ableton Live to play some sounds, while also playing other instruments, and so he wanted to be able to control Live with his feet. Ableton Live is very nice, control wise, in that it is easy to map keys on the keyboard to do almost anything, and also that you can easily switch over to a mode where two rows of keys map up to a little more than one octave on a musical keyboard.

The switches for each pedal

The switches for each pedal

Having some pedals from old organs laying around, we decided they would be ideal for the physical part of the interface. And as they, on the lowest level just consist of one full octave of switches, the easiest thing was just to make it work like a keyboard. Mapping the “white” pedals to “asdfghjk”, and the “black” to “wetyu”.

I ripped the controller board out of an old USB keyboard, and used a multimeter in continuity mode to find out which pins matched the keys we wanted. Then it was just a matter of solder two wires from each of the pedal switches to the right pins on the controller card. Since some keys shared pins, we also matched those up, and connected the matching pins, to reduce the clutter.

The pedals all connected to the keyboard controller

The pedals all connected to the keyboard controller

Now it is just a matter of planning and rehearsing, finding out what sounds to map to what pedal. Having the ability in Ableton Live, to also have different trigger modes on the sounds makes it a very nice program for live performances, but I guess that was the whole idea of the software, so it’s not surprising.

The Viscount c.100 volume pedal

Viscount c.100 volume pedal

Viscount c.100 volume pedal

Just a small update on the organ I have been gutting.

I have found out a lot, and will write some more about it real soon. I just wanted to write some words on this recent find, as I think it is a bit cute.

Earlier today I took the whole organ apart, to save some room in my studio, and was just trying to figure out the volume pedal’s resistance and stuff, for use with a guitar or something, maybe. Anyway, using my multimeter to measure the leads from the pedal didn’t give me any clues, so I opened it up.

Instead of the potentiometer I expected to find, the makers have used a small light bulb, and a light dependent resistor in a small room under the pedal. When you move the pedal, a plate divides the room more or less, and thus letting more or less light in on the LDR. Not very advanced, and not a new concept (to me), but I thought it funny that such a solution was used here.

Lamp and LDR in the Viscount c.100 volume pedal

Lamp and LDR in Viscount c.100 volume pedal

I have also figured out, in theory, how to hook up the spring reverb, and hopefully that will be something I will write about in my next post, as I am gonna build a small effect box to have it in. The plan is to make it both usable as a guitar effect, and as an insert effect in a mixer.

Gutting an old transistor organ

I’ve had an old Viscount c.100 transistor organ standing around in my
studio for quite a while, and I’ve finally come around to start gutting
it. The goal is to learn a bit more about electronics, as well as try to
be able to use the spring reverb, the rhythm generator and the pedals
for something else.


What I am thinking with the reverb is to put it in it’s own box, so that
it can be used as an insert effect on mixers, or as a pedal effect for

The rhythm section can be used for what it is for, but I want to build
it into a smaller box, so it is portable and can be used in different
situations. Also, since I have figured out it gates the bass pedals, I
will try and add connections so it can be used as a trigger/gate for
other stuff.

The pedals I will build into a box, with the oscillators so that it can
be used on it’s own as a foot driven bass keyboard for live performances.

I am self thought when it comes to electronics, and I have not studied
it very well, but I do know some basics. So this is a challenge, but a
good one.

In lack of a proper oscilloscope I am using xoscope with a sound card probe.

More pictures, and some sketches will come when I figure out something
useful, and have organized my notes.