Retro handheld analogue percussion synths on eBay

I saw these on eBay and I knew that I had to post on them. They look great, and there are even a couple of sound files to listen to what they sound like.

Here's what the listing says on eBay:

"Syntom" and "Synwave" original 1980's electronic analogue percussion modules.

The designs for these modules were originaly published around 1981 in the magazine "Electronics and Music Maker" (the Syntom being endorsed by Ultravox's drummer, Warren Cann). I built the circuit boards at the time and used them in various experimental drum machines during the 1980's. Whilst clearing out some cupboards last month, I came across the 2 cicuit boards and decided to have a go at re-manufacturing them. I searched the internet for scans of the original articles and put them together again with new cases and potentiometers. They are both analogue designs and do not use samples.

SYNTOM: This simulates toms, swept toms (as per "Love don't live here anymore"), bass drums and a range of chirps and squawks.
The controls are:

Pitch
Sweep (for determining how much the pitch changes as the sound decays)
Decay (length of sound)
Volume
SYNWAVE: This is a filtered white noise generator for creating claps, snares and resonant tom-like sounds. The filter is distinctly non-linear and quirky and will burst into self oscillation at certain combinations of settings.
The controls are:

Pitch (of the filter)
Q (resonance of the filter)
Decay (length of sound)
Volume

These modules can be triggered in several ways:

By tapping the case (internal sensor fitted)
By plugging a piezo crystal buzzer or crystal earpiece into the "trigger in" socket (1/4inch mono jack). The trigger can be attached to a drum pad or surface for hitting. I used to tape a crystal earpiece to a drumstick and hit any nearby object (bass player?) during live performances. To get you going, I have glued a jack socket to a crystal transducer.... you can tape this to a suitable object and connect to the module by a standard jack to jack guitar lead.
By using a 5 to 9v voltage pulse on the trigger input. A long time ago I built a simple sequencer that could be programmed with basic drum patterns by changing a bank of switches. Sadly it is long lost. You could probably output suitable pulses from a PC via the parallel port, but you'd need to get advice on that. You can also use a 9v battery with a push button to trigger the sound. The syntom did not originally have the trigger input, so I took the input configuration from the Synwave design. Don't worry about getting the polarity of the pulse wrong.... there is a capacitor preventing direct connection to the circuit.

Each unit is powered by an internal 9v PP3 battery and there is an on/off switch on the back of the case (next to the trigger and output sockets). Output is via a 1/4 inch mono jack.

Most of all I love this original advert and circuit diagram for them.