Hello John,
Tried it but with our range it doesn't work. The problem with such adjustable current sense resistors is that the resolution for higher currents is poor. It all piles into one corner of the pot.
It looks like a custom potmeter or long term a little ASIC.
Regards, Joerg
"Joerg" schreef in bericht news:7WxBf.14170$ snipped-for-privacy@newssvr13.news.prodigy.com...
Perhaps a cheap low voltage sot-23 opamp will do, howland current source, allows you to use any pot you like. LMV321, 21 cents a piece.
-- Thanks, Frank. (remove \'q\' and \'.invalid\' when replying by email)
-- I understand. What would you like the the "open" resistance of the pot to be and, say, its resistance when the shaft was at its halfway point around the arc?
Hello John,
Hmm, one of those cases where I couldn't see my own reply. Guess the news server swallows some posts again.
Ideally full open would be 45ohms and minimum 9ohms. But that's not critical, I could use a mechanical peg. A halfway point around 15ohms would be nice. Or less, since the high current values will still continue to cram themselves into the corner from there.
When using a series resistor of 9ohms to cap the max current the halfway point would need to be well below 10ohms.
Regards, Joerg
Hello Frank,
Thanks. The cost would certainly be ok here but the Howland requires a path to ground, or a Hi-Z load sense. Since there is no power switch here it would drain the battery.
Regards, Joerg
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