Looking for schematic (or kit) for a Graymark 122 - Computer Sound Effects Kit

Thread Starter


Joined Feb 21, 2009
Hi all.

This is a long shot, but the kit that got me started into this hobby back in 1979 was a Graymark 122 "Computer Sound Effects Kit". I have my dad to thank for not getting me what I asked for that Christmas (a space shuttle model that spacey sounds) - but instead getting me what I needed - an electronics kit that you had to solder together that made spacey sounds - along with a lifelong love of electronics.

So the kit - I want to find/build one again, but I have been watching eBay and searching for literally years and the only trace I have found is one picture on Worthpoint of an auction long since dead and gone. This picture at least proves I have the correct number and name "122 - Computer Sound Effects Kit" but other than that I can't find a trace of it. Oh, I did find a reference in the sales section of Radio Electronics magazine. (attached)

I am hoping that one of you fine people might have the schematic (or even a full kit??) so that I can rebuild it.

What I remember: It used two 555 timers - one to make the sound and one to control the speed. I THINK it used a 7 or 8 bit binary counter chip, and it fed the binary output into a series of resistors that in turn changed the frequency of the tone produced by the first 555. I remember it had 3 potentiometers, one for speed, another for pitch, and a third distorted the sound. It also had a switch to make the sound "blip" or "glide". Re-creating the circuit might not be terribly hard, but getting the correct resistor values to properly create the sound would be pretty tough. An old schematic or assembly guide would be great!

So, any help out there?

I did contact ESSales which seems to be a reseller of graymark old stock, but they have no clue about this model.

Many thanks!
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Joined Oct 2, 2009
No need to go searching for some obscure sound kit. We can recreate whatever you desire right here on AAC.

Rather than building from a kit you can learn a lot more by experimenting with various circuit configurations on a experimenter's prototyping circuit board.

First steps:

1) Get a solderless prototyping breadboard like this:
2) Get some male-to-male jumper wires or just plain solid insulated 24AWG hook-up wire.
3) Get a 5VDC power supply. A wall adapter from a second hand store will do fine.

4) Get an assortment of resistors, capacitors, and some 555-timer ICs.

Start off with a simple 555-timer circuit.
The later on try a dual 555-timer siren circuit.


Come back here with your questions and some more ideas.

Thread Starter


Joined Feb 21, 2009
Thanks. I appreciate the effort in your reply, and I should have been more clear. (I minored in electronics in college). What I am after is the exact same circuit that started me on this journey 40 odd years ago. Its a nostalgia thing to have the same circuit that started me off into electronics and a fond memory of me and my dad. My dad is fortunately still with us, and I would love to this build with him as well as a thanks for starting me off with this.