My new VCO

[Martin Czech]

Nice circuit! (I have a problem with the .pdf, in the top left corner
all semiconductor type names are at the same point...)

> With the VCO running at rather high frequencies, a (possible)
> leakage of the thyristor (is there any ? Martin ?) would not be
> harmful either.


Me ?
Depends on the transistors, of course. I you have bad luck with a bad
leaky Q1 or Q2there may be a problem. Select? I think the diode in the
thyristor loop is there to controll the pull up point where the devices
shuts off, but also is some kind of voltage devider together with Q3.
For little currents the diode has a quite high resistance, but Q3 has
also some beta, this may suppress leakeage currents, preventing them from
beeing transformed into a Q1 base voltage. OTOH the Q3 is also there to
compensate temperature driven Ube loss of Q1, the trigger point should
be fairly stable...


m.c.