PWM controller correction

[rauscher at icst.com]

For those of you who didn't read through all of my response
to Tom's questions, there is a potential got'cha. I have
the 12v vehicle power being used to power up the PWM portion
of the circuit.

Vehicle volts vary greatly.

This will cause a change in duty cycle as the vehicle volts
change. Don't think we need this 'feature'.

But, the fix is easy, use a LM7805 3-terminal regulator to
create a stable 5 volt supply. Run the PWM portion (LM393),
from this supply. (Checked the data book, LM393 is spec'd
down to a 2V supply).

This will also change the Vin control voltage to 0 to 5 volts.
This should be better all around, as this will allow you to
create a more stable control voltage.

I'll breadboard this tonight, test it out, add the changes to
the schematic, add in missing component specs, and get it posted.

BobR.

Thank you for your patience, we now return
you to our normally scheduled program.

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