From yahoo Sent Mon, Sep 19th 2016, 07:04
From yahoo Sent Mon, Sep 19th 2016, 07:04
> So today i was lucky enough to write in on an order for both
> A-111-2, A-111-3 modules and the A-184-2 [ yeeeej :)] Following
> question comes to mind regarding the latest discussion abouth new
> vco module thru-zero capablities and the mentioning of the JH3
> dual cem 3340 vco module. The old JH3 dual vco schematic [
> http://jhaible.com/legacy/tonline_stuff/hj2vco.gif ] shows 7
> different sync capabilities between vco a/b. Could these sync
> functionalities be duplicated in a supposed patch with the
> A-111-2+A-111-3 and some logic/inverter modules?
Adding the corresponding circuits should be possible. Let me know your
results as the thru zero circuit we tried so far (based on an internal
Curtis information) does not meet our expectations. The toggling during the
zero transition does not work as it should under all conditions. Sometimes
the oscillation totally stops and comes back to live only by turning the
supply off/on. Maybe it has to do with Rev.G of the CEM3340. We discovered
that the CEM3340 stops working as soon as the linear reference current at
pin 13 becomes zero for a longer time (but that's essential for the thru
zero transition). If the transition is fast enough (i.e. modulating with a
higher frequency) and the linear current becomes zero for a short time only
it works. But as the modulation frequency becomes lower or one tries a
manual thru zero transition the oscillation stops sometimes. Maybe we still
have a mistake in the circuit but I don't think so. We just took an old
A-111-1 and modified it a bit so that the DC current voltage at pin 13 can
be manually adjusted (not a fixed value as in the standard application of
the CEM3340 by means of a resistor connected to +U). When the current
becomes zero the oscillations stops (as expected) but sometimes the VCO
comes not back to life when the linear current is increased again. Turning
off/on the supply is the only way to re-start the oscillation. We will have
to check out if this is valid for the original CEM3340 too or a drawback of
rev.G only. If Juergen Haibles circuit does not have this drawback we may
use his circuit and pay tribute to him posthumously.
Best wishes
Dieter Doepfer
P.S. The first batches of A-111-2, A-111-3, A-138o/p and A-184-2 have been
shipped to Alex4 and should be available from dealers soon.
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