Jim,
Very interesting circuit since the MOSFETs function like a high-power,
active voltage divider. I did note that the non-inverting input to U1a may
be susceptible to the effects of both the normal screen voltage and perhaps
a flash from the screen. However, provided that Z1 acts quickly enough and
R10 remains intact, then concern is probably minimized. Still, it may make
sense to Zener-clamp the non-inverting op-amp input to a level just above
the value found in normal operation. Then, if adding Zener-clamping, I
think it would be a good practice to add series R at the non-inverting input
of 1K. The input Z to the non-inverting input of the LM358 is quite high,
allowing for some additional series R protection.
Paul, W9AC
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|