Building an electronic music scale instrument

[d4d4ng]

Hi,
I need a guide to build an electronic musical instrument that can play 2 octaves of musical notes. The output should be combined by small audio amplifier to produce notes on a speaker. Should I use multi 555 to produce each note or can I use 555 with multiple tuning circuits. Can I use discrete components to build the the note producing circuits. Please show me the diagram / circuit.
Thanks in advance.

Amri

 

[Dr.EM]

You could build it using a 555, you won't need one for each note. You just put a resistor for each key (a preset would be best) and that will set the pitch for that key. You won't be able to play more than one note at once though. A more common circuit is made using a transistor and transformer, but is quite unstable, i'll post it later if you want.

 

[audioguru]

A single 555 oscillator can play only a single musical note at a time, no chords. Its frequency isn't very stable nor accurate to use multiple oscillators to make musical chords.

If anyone still makes them, a "top octave" generator should be used for accurate musical notes. You could also make a complicated digital circuit to produce accurate multiple notes.

A 555 or digital circuit produces a square wave, which sounds more like a buzz instead of a tone. You would need filters for each one to make pure tones. You need wave-shapers to make different-sounding tones. You need attack and release contol so that the tones are not abruptly on and off. :lol:

 

[Nigel Goodwin]

As suggested, a 555 would be fine - as long as you only want monophonic? (only one note at a time). The famous "stylophone" was just a simple astable multivibrator with different value resistors switched in with the sylus.

 

[d4d4ng]

Hi All,
Thanks for your replies that confirmed my idea for using 555 but looks like is has disadvantages. I'm interested to use transistor and transformer :?: to produce a tone. Will Dr. EM provide the schematic please ?.
So, I have to consider filters to get the tones I need and a sustain and decay circuit ( is it a right term ? ) to prolong the tone ?
Is there a digital circuit ( IC ) to produce multiple tones as in audioguru's post ?
Thanks in advance.

Amri

 

[Dr.EM]

Ok, here you go. This is the type commonly used in toy organs. The nice thing about this is that you can get away without needing the AD envelope, and it can directly drive a speaker with some volume (good enough for use in a quiet place at least). I have not tried this as I have drawn it here, so I advise testing this on a breadboard first. Each of thos 100k pots will set the picth for that corresponding key switch. The overall frequency is determined by the 0.05uf cap, and the "tone" can be altered by changing the 0.1uf cap (although this does affect the frequency too, a larger cap makes it more bassy). The transformer is an output type, 1k to 8ohm CT or similar. The transistor is a PNP, try any you have in this, the one specified is rare.

In the original, the circuit is switched on the positive rail, this is witched on the negative, as that is where the resistors are. I only assume this makes no significant difference.

https://www.miniorgan.com/ That may be of interest to you, I found it interesting looking at them

 

[d4d4ng]

Thanks Dr. EM for your circuit. I'm glad that I can follow the circuit, but if I use a NPN transistor I can just flip the battery, can't I?
I will try to do breadboarding and will post the result but it will take time

 

[Nigel Goodwin]

Thanks Dr. EM for your circuit. I'm glad that I can follow the circuit, but if I use a NPN transistor I can just flip the battery, can't I?
I will try to do breadboarding and will post the result but it will take time

Yes, you could use NPN and flip the battery, I would also add an electrolytic across the battery as well!.

 

[d4d4ng]

Dear Nigel,
Thanks for your advice, I'll see to it.

Amri