lectrobug again

[ed calhoun]

not much dis-cuss-in on the the vw/ev conversion so thought I would give it another kick. Decided against the generator- will add batteries equal to the weight of the generator. Got a 400amp fuse this week and am almost ready for the second trial run. Need to modify the voltmeter that wilderness ev sent from 50-150V to something that will measure my 36V battery pack. Think I can put in a resistor shunt but not sure how much. I could go to the book and cipher it out but think trial and error may be easier unless someone might be able to tell me what size resistor to use.

Thanks Ed

[Phil Feinstein]

I don't think you can add resistors to step "UP" a voltage; I think you're looking at either recalibrating your voltmeter or using a conversion point (like an optocoupler or a boosting voltage regulator) to make a voltmeter calibrated from 50 to 150v work with a system of 36v.

[Phil Feinstein]

Splitting the difference between 50 and 150, you'd get 100v which is roughly 3 times the voltage of 36v.

Maxim IC has a power supply cookbook online. Take a look at http://www.maxim-ic.com/cookbook/powers ... /CB185.pdf and you'll see a power supply that provides roughly a 3.5x voltage step up. This doesn't solve the problem completely; the supply won't accept 36v and won't provide an infinitely variable output based on the voltage input, but you can get the idea of where to go next.

[Phil Feinstein]

There's also a great site for analog circuits, one of which being a comparitor circuit using an Op amp. Take a look at http://www.ibiblio.org/obp/electricCirc ... EXP_6.html ; This can be modified for any input voltage and has inifinitely variable output voltage.

[ed calhoun]

Phil thanks for the reply and for not calling me dumb a**. Must have had an brain flatulance. Looked at the circuits you told me about. They look good to play with but might be a little involved to just cut a voltmeter in half. Think I will just hang a VOM on the dash till I build up my battery pack to a voltage the 50-150V meter will read
Thanks Ed