MAKE: drumsynth for 20euro (maybe)

[playthatbeat]

So. In EMM in 1981 there was an interesting article: THE SYNTOM.. a percussion synth, using a transducer to dynamically trigger a synth based around a CA3080.. basically you slapped it and it made noises.. The parts would come to nearly nothing, all you had to do was make the board and solder away..

Have a look, then do the math..

The only ropey bits to find now are:

* The PCB - looking into making a batch as i type
* the CA3080 chip - on ebay, about a euro a pop from vintage stockists
* the 3403 quad opamp - rare now, can cost up to 10euro

I reckon You could use audio to trigger it, instead of relying on the crystal earpiece.. but for now, i'm gonna say lets build it as nature intended..

In the pics attached there is a template for etching a board.. the measurements are: 95mm x 32mm from the INSIDE EDGES OF THE CORNER MARKERS. this is so You can get it the correct size to print it.. It was scanned at 300dpi.

So.. It should sound like a 1-osc version of a JSH drumsynth, or i suspect very like a coron drumsynth since it appears to be exactly the same design.. So that lots of delicious pings and pops and sweeps.. Whatever, it's analogue, unique and not a fuc*ing plugin.

I will update the thread when i find the parts - i am looking for everything in lots of 10 with an aim to get 10 kits together for me & 9 other like-minded lunatics, or if (more probably) nobody cares, make 10 of the things for me to play with!!

[playthatbeat]

Yes, the CA3080 is all over ebay in various forms, got "10,Original Harris CA3080 CA3080E IC Chip's for OP AMP" for $16 inc. shipping to ireland.. Yes, i know, thats about a euro a pop.

as for the 3403 - there is a nice rail of them here by ON semiconductor, i think, for pittance.. apparently it's "Similar Performance to Popular MC1741C" - which i have a tube of here after repairing the matrix 6.. or something.. but lower current draw.. do we care about that nowdays? still to confirm if this 3403 is the same, but they DO seem rare now in the original form..

edit: turns out i had a tube of 3080 here! doh!

[playthatbeat]

after debating the pointlessness of building one of these last night, and looking more closely at the circuit and (more importantly) the controls, it's unlikely the unit will produce anything other then whipping and pew-pew noises - it having no higpass and bandpass filters to spice things up.. the thing about the JSH and coron was they had delightfully nasal filters onboard that added a FIZZ to proceedings.. i dunno, kinda still want to make a batch and attach them to my cats and make them fight.. also: the cheap 3403 i keep seeing everywhere are SMD devices.. MEH!

also: looking at having a small run of boards made, and aside from the cost being a bit silly, most small-run places require a PCB file.. Laying out the stuff in a PCB CAD system so we can make a PCB file looks like a royal pain in the hole.. looks like it may have to be done.. FFS..

OK, some digging - and there seems to be a lack of recent utilitys to convert images to PCB files, but there was a rush of them about 10 years back, for converting .BMP files (ie company logos) to PCB files that could be included in the designs for silkscreening boards... It's possible that the image from the article above can be converted to just such a file using one of these, then imported into a modern PCB design program, then changed to copper rather then ink, and have the holes added to the design.. Need to make a true-to size black & white .BMP of the board design next.. maybe..

after some digging i found the attached freeware utils for windows/dos systems, with interesting notes to be made here