AW: [Doepfer_a100] Soft Sync on A111
> -----Ursprüngliche Nachricht-----VCOs.
> Von: Josue Arias [mailto:josue.arias@...]
> Gesendet: Sonntag, 6. Februar 2005 12:59
> An: Doepfer_a100@yahoogroups.com
> Betreff: Re: [Doepfer_a100] Soft Sync on A111
> Hi Florian,
> You are wrong about the A111...The A111 uses a CEM 3340 but the module
> is not a raw CEM module, it have circuits around the sync inputs,
> comparators I think so it needs to see a rising or falling edge as all
No. The hard and soft sync inputs have no additional circuits but are
connected directly to the corresponding sockets of the A-111. Only pull down
resistors (if no signal is connected to the sockets) and z-diodes for input
protection/voltage limitation are used.
- I have to correct myself
> a zener diode for eleminating positive signalsThat's nonsense: The Zener Diode is of course for limiting the incoming
signal (I mismatched this in my brain with a sentence from another text,
which suggested to insert a normal diode, that blocks the positive part
of syncing signals).
- Yes, I`ll try a short inverted pulse but why wasting an inverter? the
resistor and diode ARE there for driving the sync with a saw wave!
The good about the modulars is that you can end doing the same
operation using several approaches! :)
> > You can check the Manual.
> The schematic of the A111 shows the blank input for the Pin 9 of the
> CEM3340 (only additions are a pull down resistor and a zener diode for
> eleminating positive signals (schemo see page 1 of the service manual
> and explanation page 7). So beside of the zenerdiode and the pulldown,
> the Softsync input is designed as suggested in the datasheet.
> The Datasheet says for this connection on page 6:
> "[...]Finally, the oscillator may be soft synchronized by negative
> pulses applied to the threshold voltage pin (pin 9 of 3340[...]). These
> pulses cause the triangle upper peak to reverse direction prematurely,
> causing the oscillation period to be an integral multiple of the pulse
> periode. [...]"
> So according to the Doepfer schematics, the Curtis datasheet and - as
> minor argument - to my experience, a simple short pulse is perfect to be
> used as soft syncs master signal. Of course a saw will do something
> similar, but that shouldn't prevent you to try a pulse. ;-)
- Hi Josue
> Yes, I`ll try a short inverted pulse but why wasting an inverter? theHmmm, could you explain why?
> resistor and diode ARE there for driving the sync with a saw wave!
Florian (always interested in deepening his electronic skills)