DIY-WB & Dataq 194?

[Phil Hunter]

> I would parallel the DIY-WB output resistor (R15) with a 10
> ohm 1/4w resistor. You will lose the level of protection
> that the resistor provided. It may be a reasonable tradeoff.
> 
> BobR.

Or use one of the extra 15 ohm resistors.

Another option is to connect U4 pin 6 to J8 instead of pin 7
so the op-amp actively compensates for the voltage divider
error. The trade-off is a short from J8 to 12V will likely
blow U4 and perhaps more (input voltage exceeds supply
voltage), a short to ground shouldn't be a problem. Even
this risk can be minimized by using one of the spare IC
spaces for a seperate op-amp that uses Vbatt (U5 pin 3) for
power rather than +4V (U5 pin1). The TL082 dual op-amp
available from R.S. seems like a good candidate.

regards,
philh
(digest)


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