DIY alternative to Quazar ZXTT module for Ed Brindley’s YM2149 Sound Card (rev. 5)

[Massimo]

I built my own alternate version of the Quazar ZXTT module using a 74LS90 in the bi-quinary configuration to divide by ten a 17.7344MHz oscillator.

This still provides the 1.77344MHz clock to the sound chip to match the ZX Spectrum.

I got the schematic from here: https://incbtech.com/circuit-bench/829-frequency-divide-by-10-ttl-circuit-using-the-7490-cb253e.html

Here's my module (16MHz just for testing):

[Martin Giese]

Nice little hack!  I like that you sawed off a corner of your perf board to make it RC2014 compatible ;-)

Martin

[Massimo]

I since ordered PCBs to replace the protoboard, I'm attaching the gerbers if anyone wants them.

To fit properly in the socket it's necessary to trim a little bit the pin headers