| Electronics > Beginners |
| Will this work (optocoupler over shunt)? |
| << < (7/11) > >> |
| spec:
--- Quote from: ArthurDent on December 07, 2018, 06:45:10 pm ---Here is my final variation of the detector that may address some concerns and, like I said, if any of these various circuits were actually built and tested there could be minor or major changes that might come to mind. I think stenespen now has enough information so they can pick and choose what they think might be best for them and try that circuit. --- End quote --- Living dangerously there AD. :palm: |
| StillTrying:
Isn't anyone going to do an Arduino version. >:D |
| Zero999:
--- Quote from: spec on December 08, 2018, 11:14:00 am ---Below is the schematic for a precision version, with hysteresis for H99, and an NMOSFET for AD. The trouble is that it uses non jelly-bean components, which may not suit the OP. --- End quote --- Here's a version which uses jell bean components. The turn on and turn off currents can be independently set if necessary. V2 can be the TL431 or similar voltage reference. It uses a PNP output but it can easily be modified to work with an NPN BJT, N-MOSFET or P-MOSFET. It's a variant of a circuit I posted earlier this year, which is linked below. https://www.eevblog.com/forum/beginners/the-simplest-thermostat-with-programmable-thresholds/msg1432025/#msg1432025 EDIT: I haven't included any filtering, which would be a good idea. |
| spec:
--- Quote from: Hero999 on December 07, 2018, 11:17:27 pm --- --- Quote from: ArthurDent on December 07, 2018, 06:45:10 pm ---Here is my final variation of the detector that may address some concerns and, like I said, if any of these various circuits were actually built and tested there could be minor or major changes that might come to mind. I think stenespen now has enough information so they can pick and choose what they think might be best for them and try that circuit. --- End quote --- That will not overcome the issue of the transistor clipping the comparator's output. If you want to use the comparator's non-inverting input for positive feedback and don't want to use a MOSFET, then use a PNP BJT, but the logic will be reversed. You seem not to believe me when I said the relay coil's inductance doesn't generate any noise. Where did you get that idea from? It's compete nonsense! --- End quote --- Q2 e/b junction is vulnerable here, as is the open collector transistor in the comparator. Also, you would be losing more drive to the relay than with a saturated collector arrangement, like the original. Attached is a schematic showing a simple and safe way to maximize drive to the relay and provide hysteresis (functionally, the TS391 comparator is just a singe comparator version of the original dual twin comparator LM393): |
| T3sl4co1l:
Vulnerable to what? I wouldn't recommend running the relay coil wires to the outside world where ESD and maybe surge may be a problem. Tim |
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