Having a zero-center +/- 5 volt meter I used a multiplying
resistor to make it read +/- 25 volts. Then I built a
bridge circuit consisting of two 50 volt zener diodes
and two resistors (plus a couple forward biased diodes
to trim the voltage and ad some temperature compensation).
Now it reads 100 volts at center, and +/- 25 volts at the
extremes. For my 96 volt pack I can treat it as voltage
or percentage. (100 volts +/- 25%)
It lacks some linearity at the extremes, but not enough to worry about.
My next version will use a normal (not zero centered)
voltmeter. The circuitry will be remote, sending only
about 5 volts through the firewall, fairly well isolated.
New subject:
High quality meters are often delicate, and may not last
long in a mobile environment. I look for aircraft meters
on surplus. (I remember dropping in from about 25 feet
in an Aircoupe!)
John in Sylmar, CA
PV EV
_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev
resistor to make it read +/- 25 volts. Then I built a
bridge circuit consisting of two 50 volt zener diodes
and two resistors (plus a couple forward biased diodes
to trim the voltage and ad some temperature compensation).
Now it reads 100 volts at center, and +/- 25 volts at the
extremes. For my 96 volt pack I can treat it as voltage
or percentage. (100 volts +/- 25%)
It lacks some linearity at the extremes, but not enough to worry about.
My next version will use a normal (not zero centered)
voltmeter. The circuitry will be remote, sending only
about 5 volts through the firewall, fairly well isolated.
New subject:
High quality meters are often delicate, and may not last
long in a mobile environment. I look for aircraft meters
on surplus. (I remember dropping in from about 25 feet
in an Aircoupe!)
John in Sylmar, CA
PV EV
_______________________________________________
For subscription options, see
http://lists.sjsu.edu/mailman/listinfo/ev