EH Random Tone Generator

[Zero the hero]

While surfing the net I've found this unit made by Electro Harmonix... http://electroharmonix.ronsound.com/articles/rtg.html  
Has anybody the schematic of this very strange unit or knows how this pedal works?
Thanks!

[Marcos - Munky]

Looks cool!!! Hope somebody have a schematic of it. I really liked it.

[p1_ind]

I built a dual tone generator for a friend once using a couple 4046 ICs.
I made it so that each oscillator had slightly different speed ranges.
You could use them one at a time or combine them for some strange ATARI like sounds.
When I was testing it I think I just sat and twisted the knobs and flipped the switches for an hour just making strange sounds.

Sometimes the simplest, most annoying things in the world bring us the most joy!

[Peter Snowberg]

Sometimes the simplest, most annoying things in the world bring us the most joy!

Isn't that the truth. :mrgreen:

Noise makers can be so much fun..... I remember years ago playing with a keyboard that made all kinds of odd noises and having a ton of fun. The next guy to start playing with it had the same experience and after several minutes he just busted out laughing about how awful it sounded but there was no question we were having too much fun making these awful noises.

Take care,
-Peter

[puretube]

anyone remember the SN 76477 ?

[RDV]

anyone remember the SN 76477 ?

SN76477, TI, 1975?, Sound generator

RDV

[Peter Snowberg]

anyone remember the SN 76477 ?

I still have one of those in a box somewhere. :mrgreen:

[puretube]

yep, RDV/Peter...
bought a dozen in `82 for an electr. drumset - took a dozen frisbees and stuffed them with foam, put a cheap crystal mic in their middles for pick-up/trigger glued them to round wooden boards with selfmade hardwares to mount them between 2 mic-stands...

hot fun in summertime...

28pin "maxi" DIL ;
LFO (tri & sqr),
Noise generator & lp-filter,
One shot multivib,
Envelope generator for AM or product-mod,
VCO (sqr/pwm),
CV-mixer,
logic control for some of above functions...

[zachary vex]

While surfing the net I've found this unit made by Electro Harmonix... http://electroharmonix.ronsound.com/articles/rtg.html  
Has anybody the schematic of this very strange unit or knows how this pedal works?
Thanks!

that's just a random sample-and-hold circuit driving a simple oscillator.  you could probably makes something that sounds almost identical by stealing the random sample-and-hold engine from a maestro sample and hold pedal, and using it to drive a simple triangle-wave oscillator instead of the filter it drives in that circuit.

the glide function is terrible on the EH pedal.  you can make a glide that sounds a lot better by using a smaller rc time constant on the glide circuit.  this can be lifted from synth schematics, often from the keyboard controller schematics.

[StephenGiles]

I thought I had that circuit, but it was the Talking Lights - not very thrilling!

[moosapotamus]

Talking Lights...? What's it do?
Never heard of it. That was an EH pedal thing?

~ Charlie

[Nasse]

:shock: Sounded like crappy 50´s science fiction movie soundtrack. My kids say "boring, not interested" when I say let´s see an interesting old b/w movie like "Monster from **** swamp" or something. Not much hit potential I´m afraid, but I might be wrong. Must try my Korg Pandora if I can recreate some similar sounds... That Tommy Bolin fuzz sample was nice. And I could buy a vintage EH Black Finger schem cheaply there...

BTW I don´t like the looks of new EH "Freedom" amp, the old one was much more uglier and quess ten times louder. I sadly traded one for old 50W Marshall in late 70´s. Well that was an amp with real sick attitude...

[Paul Perry (Frostwave)]

Anyone doing a glide to smooth out a random step, maybe try a glide with much faster attack than decay, would sound more 'organic'. The trouble wiht simple randomn sounds, is they are TOO random.

[Yuan Han]

"glide" is like "portamento" right ? (saw it in cmos cookbook in a sample n hold circuit)

a circuit with S&H driving a oscillator would be pretty complicated right ? first you'll need a S&H then somethign like a harmony generator based on phaselockedloop.

I think a s&h (like mastro sample n hold) sounds pretty much like a "tone generator" already, but tahts just me .

Han

[Paul Perry (Frostwave)]

"
a circuit with S&H driving a oscillator would be pretty complicated right ?

Not at all, the S&H puts out a voltage which you would use to drive a voltage controlled oscillator. Plenty of simple audio VCO circuits out there, I like the one in the LM13700 application notes, but one based on the 4046 pll chip would be easier probably (yeah it's a pll chip but you only use the oscillator).

[Paul Perry (Frostwave)]

"
a circuit with S&H driving a oscillator would be pretty complicated right ?

Not at all, the S&H puts out a voltage which you would use to drive a voltage controlled oscillator. Plenty of simple audio VCO circuits out there, I like the one in the LM13700 application notes, but one based on the 4046 pll chip would be easier probably (yeah it's a pll chip but you only use the oscillator).

[Zero the hero]

Hey, thanks a lot people!
I think I have to study very hard about PLL, S&H, and stuff like this.
Yeah, this unit is not that cool, after the weirdness appeal of the first look, I think that it will get boring very soon, but it could be a good chance to learn how S&H circuits work.