What part do i need?

[trad3mark]

Hello children of the night,
I'm looking for a part but i don't know what it is. I'm planning a sort of optical multiwave tremolo. I have a vague recollection of coming across an IC before (I think it was 16pin) that was a sort of multi-waveform generator. As far as i can remember, it did Sine, triangle, square, saw and random. Thing is, I've looked about on Radionics for the last while, and I'm not actually sure what it is i'm looking for. The plan is to use a chip like that to power a LED/LDR. Any one able to shed some light on this mystery part (no pun intended!)?
Cheers,
N

[anchovie]

XR2206?

[frequencycentral]

Is he talkin bout this?

http://www.diystompboxes.com/smfforum/index.php?topic=76436.0

[trad3mark]

yeah kinda like that rick, but where that's an expert mode trem, this is superbeginnermode trem. I was hoping to get a chip that's readily available from my local supplier. In an ideal world, it'd produce all the waveforms that druids does, but i'd be happy with a selection really.

something like that 2206 would do it. Even if i knew the name of the part, i'd be on the right track. So it looks like I'm looking for a "Function Generator" or "LFO" right???

[Galego]

ICL 8038?

[trad3mark]

ICL 8038?

discontinued according to RS.

[Galego]

ICL 8038?

discontinued according to RS.

They all seem to be... Max038, NTE864. I could still find NTE864's on mouser, but they are really expensive.

I would suggest getting into Microchip PIC or something like that. Much more versatile and cheaper. I've posted basically all you need to do that, (including the code) here in the forum.

[trad3mark]

Isn't there a random shape LFO in the Maestro FSH-1?

[Seven64]

i built a signal generator with an lm348n

[trad3mark]

what waveshapes?

[smallbearelec]

Hi--

ICL8038
http://www.smallbearelec.com/Detail.bok?no=856

XR2206
http://www.smallbearelec.com/Detail.bok?no=226

Regards
SD

[frequencycentral]

Isn't there a random shape LFO in the Maestro FSH-1?

Well, kinda. Sample and Hold (or random) is made up of three parts: noise generator for the random voltages; LFO with very short mark/space ratio; sampler made up of a cap to hold the voltage and a FET switched by the LFO to sample the voltage.

[slacker]

A simple opamp based LFO will get you tri, square and saw. There's some example's here

http://electro-music.com/forum/viewtopic.php?t=32372

The first one by Nicholas is particularly good, and you get flashing LEDs thrown in for free. The skew pot makes the triangle go from ramp up at one end, through triangle in the middle to ramp down at the other end, it also controls the duty cycle of the square wave. If you want sine as well you can add clipping diodes, like in a distortion pedal after the triangle out, with a bit of boost afterwards to get the level back up.
Random is a bit trickier you can go with the sample and hold method like in the FSH-1, or if you don't mind something that only sounds random you can get good results with something like this http://www.cgs.synth.net/modules/psycho_lfo.html.