[sdiy] Jen SX1000 sync mod

[Neil Johnson]

All,

Last night I had a fab brainwave regarding hard-sync on the Jen SX1000.

Background: the Jen uses a monostable formed around a 4013 D-type to reset
a current integrator, triggered by the main oscillator, and thus
generating the sawtooth waveform (the main oscillator also varies the
current proportional to frequency to keep the sawtooth amplitude
constant).

I wanted a separate reset input to this monostable to I could force the
sawtooth to reset from some other control signal.  I spent half of last
night hacking around trying to force a reset pulse into the same input pin
of the 4013, whem towards the end of the night the brainwave passed
through my grey cells and triggered the answer.

Looking closer at the schematic, the original designers had chosen to the
use Set/Reset inputs of the D-type to construct the monostable; the output
is taken from Q-bar.  BUT... they had left the D- and the Clk-inputs
disconnected.

**TADA**

Ground the D-input, and feed the sync pulse into the Clk-input.

Instant sync!!!!

He he he hehehehehehehehe..... :-)

Info, schematics, etc will be appearing soon on my Jenny page.

Cheers,
Neil

--
Neil Johnson :: Computer Laboratory :: University of Cambridge ::
http://www.njohnson.co.uk          http://www.cl.cam.ac.uk/~nej22
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