[sdiy] FORMANT VCO restoration and improvement

[Paul Perry]

If you have a two channel scope, then the thing is to look at a signal
somewhere else in the circuit that will lock the scope, then that will
stabilise the "invisible" signal (if any)for viewing on the 2nd channel.
A classic case I do all the time, is lock the scope to the mains to see
whether there is any mains frequency signal hidden on the supply rails.
I'm not familiar with the Formant, but if you are talking about a pulse that
is derived from the oscillator, then just lock to the main VCO output.

It may be the pulse is "too thin" to see, in which case a 7555 pulse
stretcher monostable might be the go. Not sure what the optimum width for
say DIN sync is (if that is what you will use it for) but I do know that
some things are a bit fussy!

best, paul perry (melbourne australia)

----- Original Message ----- 
>Now i want to add sync out. Therefore i wanted to use pin 8 of the 7413
>Schmitt Trigger. Just added a source follower here. But it didn't work. I
>can't see the pulse at the scope. Not at pin 8 nore at the output of the
>source follower. Any ideas or help here? Maybe the pulse is to short/weak
to
>trigger my scope?