[sdiy] "voltage control" on the 556

[Tom Wiltshire]

On 8 Mar 2009, at 05:04, Horton wrote:
>
> I was wondering if there's any way to take advantage of the "control
> voltage" pins on the 556...
> Am I totally barking up the wrong tree with this one, or what?

No. 555 and 556 timer chips are one of the things that got me into  
this stuff in the first place. I had a book called "Adventures in  
microelectronics" by Tom Duncan which had various circuits that made  
sounds, including one with a 556. The first timer was set up to make  
a basic pitch, and the second timer was acting as an LFO sent to the  
CV input of the first. By switching from the "triangle" (ish) output  
of the timer to the squarewave, you could make two different siren  
noises - either "Bee Bah Bee Bah Bee Bah" or  
"Weeeewwoooowweeeewooooweee" if you get the picture.

After I combined this circuit with one of the later ones (a binary  
counter using the 4512 chip) to produce octaved outputs, I was hooked  
on sound synthesis and wanted to build an analogue synth. That was 20  
years ago, and it's taken me till now to get round to it.

So my advice is just try it; 555 chips are cheap so don't be afraid  
to experiment.

T.