ldcrc
Dec 23, 2006, 11:04 AM
I have an old transmitter whose meter died but otherwise, is still going strong. I'd like to build a small LED indicator which pops off below 8.8V. It would connect through the charging jack, tape it to the top.
I have a good idea how to design this using an op amp comparator, zener reference, trimpot and LED driver transistor, all junkbox parts. There are little details about the amount of feedback hysteresis, etc. But if someone already has a bulletproof circuit for this, I would greatly appreciate it!!
Yes, I know, replace the meter! What I do now is check the voltage under load after every flight. And check the batt. capacity fairly often.
Thanks, Larry
23dec06
I have a good idea how to design this using an op amp comparator, zener reference, trimpot and LED driver transistor, all junkbox parts. There are little details about the amount of feedback hysteresis, etc. But if someone already has a bulletproof circuit for this, I would greatly appreciate it!!
Yes, I know, replace the meter! What I do now is check the voltage under load after every flight. And check the batt. capacity fairly often.
Thanks, Larry
23dec06