Musical Keyboard Chip

I used to have a chip back in the 80's that would generate 12 tones based on a single clock input. I probably read about it in one of Don Lancaster's old cookbooks. I'd start there.

Was it a SN76477?

This TI chip got me interrested in electronics.

Modern chips seem to be all DSP or microprocessor based. Atmel has a nice selection or you can get programs to run on a PIC.

I made a recent research on midi chips and found plenty sites (http://www.synthmodules.com/) with kits or preprogrammed microcontrollers for the DIY buff.

I ended up getting a nice used casio keyboard, bought a midi to soundcard cable and run FM or AM synthetizers VST modules.

I have two options for you:

The first is an oscillator, a 555 timer would do nicely. By changing the resistance you will get different notes. If you connect 12 keys with 12 different resistance values, you get 12 notes.

The second and more modern way of doing this would be with a microcontroller such as a PIC chip. Many PIC chips can be programmed to output a tone. You would need a pic with at least 13 I/O's (16F628A has 16 I/O's and would work well) 12 as inputs for your keys, and one as your output. This is more complicated because you first need to program the chip, but the schematic is less complicated since it would only be the chip and the buttons as you are asking. The advantage of the PIC if you get into it is it would give you more options. For example, you could program it to record and playback your keystrokes.

Thanx guys!

I found the 555 circuit to be the simplest and cheapest solution. The other good recommendation was that of the microcontroller. The only hassle with the PIC is that there are cheaper chips available that are custom made for synthesizers.

I think MIDI chips are not going to allow me mid tones. Anybody tried this kinda stuff?

I did land up on the atmel site and liked it.

Just the basic polyphony, a few harmonic sounds maybe (instruments) that can be programmed into the chip, a few basic beats and optional recording and playback. The last feature is not so important and can be ignored.

They are called Top Octive Generator Chips. Here is a site. You get square waves which sound kind of hollow. To get more octaves, you need to divide down the top octave tones.

http://www.organservice.com/crm/topdividers.htm