| Electronics > Beginners |
| Is there someting to improve in this design? - Milliohm meter |
| << < (4/5) > >> |
| Arek_R:
And how do you switch the current without any losses and stability issues of switching components? It can't be just a H bridge out of N channel mosfets right? xD |
| bson:
Get rid of the pot - it's better to calibrate and correct the measurements before readout since you have a µC. No need for anything adjustable. |
| David Hess:
--- Quote from: Arek_R on November 12, 2018, 10:37:40 pm ---And how do you switch the current without any losses and stability issues of switching components? It can't be just a H bridge out of N channel mosfets right? xD --- End quote --- Since it is a current being switched, the only losses in switching are limited to bias current errors which are trivial (or nonexistent if the design is clever) and voltage drops which are irrelevant. An h-bridge made out of MOSFETs could be used successfully although that might not be my first choice. |
| Arek_R:
Actually you're right, 4-20mA exists for a reason :p So what would be a better way to switch it if not h-bridge? |
| unitedatoms:
may be add button for "set zero" routine. and may be 1 more button for good known cal standard ( say some independently measured specimen in range of 10 milliohm). i dont know what is this cpu board includes, i assume it has led and lcd. also a jumper for firmware to choose between 60 hz vs 50 Hz if you decide to measure with immunity to mains background in integer amount of cycles during acquisition and averaging |
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