[HBR] Re: GB> RSGB Keyer

[Mike McCarty]

Chris Trask wrote:
>     It's not an oscillator.  It's a one-shot multivibrator with the key as
> the input.  The ratio pot determines the two rates at which the 0.22uF

If the power supply has any stiffness to it at all, there
is no feedback between the two stages. The first stage is
an oscillator and the second stage is a voltage comparator.
The non inverting input to the comparator is connected to the
"weight" pot, for adjustment of the threshhold.

> timing capacitor charges, and the speed pot/resistor determines the
> discharge time.  The inductance of the transformer increases the dwell time,
> and that may be where Ed is having his trouble.
> 
>     The second triode is just a voltage-to-current converter, with the
> weight potetiometer setting the point at which the relay drops in and out.

This conflicts with your statement that it's a multivibrator, which
requires two gain stages.

Mike
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