N. T. wrote:
> 20ma/5V lamp is 250 Ohm at 20ma and I expect it to be less than 20 Ohm
> when cold. It should be quite linear at small AC signals, say less
> than 100 mV. Feed the lamp with a constant current source regulated by
> a microcontroller.

That is basically Bill Hewlett's design for gain control of his oscillator.


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