Modules from Outer Space

Three days, three packages.

Wednesday, Tayda:

Miscellaneous capacitors, resistors, diodes, transistors. Some panel pots and a bunch of trimmers. Ripple counters, TL07xs. Screws and spacers.

Thursday — Thursday! Thanksgiving Day! USPS! I Know! — DigiKey:

MIDI sockets, JFETs, resistor arrays, 7555s, DACs, pricey op amps, optoisolators, still more trimmers.

Friday, SynthCube:

Transistor arrays, tempco resistors, and four Music From Outer Space circuit boards.

(That wasn’t the end of it: today some IC sockets and some board mount MIDI jacks arrived, and on the way are some matched transistors I should’ve included in the above DigiKey order but didn’t. )

It was time to start breadboarding another Kosmodrome module. I did the MFOS Noise Cornucopia.

This I’m pretty sure is the first time I’ve breadboarded an entire module designed by someone else rather than just diving into the PCB. I’m thinking I should do that more. It definitely seemed called for this time, because there were a couple of choices I knew I needed to make.

First I tried out a variant of the noise source recommended by Eddy Bergman, but I couldn’t get it to work with either of the two (out of three in my stash) BC547 transistors I tried; Wilson’s version did work with two out of the three (out of several dozen in my stash) 2N3904s I tried. So I went with that, and built the rest of the module. Everything worked. I did decide I wanted the high pass filter on the grainy noise to be a little less aggressive so I bumped R23 up to 10k; I also decided I liked the Q4 output on the ripple counter for the random gates better than Wilson’s preference of Q5 (see LED, above).

Then I tore it all down and rebuilt it on the PCB.

I also built one of my power header boards, to enable connecting this to my Kosmo power supply. No caps needed, they’re on the MFOS board, but I did place the power reversal protection diodes.

I’m stopping here until I get a front panel to mount the pots and jacks on. I haven’t ordered them yet, so it’ll be a week or so. And yes, I’ll plug in the ICs then too! Meanwhile there are three other MFOS boards to work on.

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