Help! I just designed a circuit and I don’t know what I’m doing!
Over on Maker Forums Social, I’ve been live-posting my design work on an enhanced returned energy dump. This all started because I am considering converting the X power feed on my mill to something where I can set a table travel speed. That means more expensive electronics than the junk that Blondihacks found in the unit and I’d like to protect it!
If the table reaches a hard stop, or (horrors) I have a tool crash that hangs up the head, I’d like the controller to stop the table motion. That would require fault detection.
I would really appreciate review from folks who know more than I do about circuit design!
This part of the circuit is the original circuit from Gecko with a few part replacements for what I find available now. This part I’m reasonably confident in.
Here’s the sub-circuit for sensing fault:
This one I have no idea whether it would actually work.
My idea is that it triggers when the motor voltage rises above about 42V. 39V through D2, 1.4V (or slightly less) through the optocoupler, and about .25V through R4. (R4 of course dissipates more power as the voltage across it increases.)
Then Vcc from a microcontroller (any voltage up to the 18V maximum of the 6N139 optocoupler) will pull up the Alarm
output high when it’s working, and pull it low in a fault. So it should be ~Alarm
I guess; it’s inverted.
Does that circuit make sense to those here who know what they are doing? I know there are several of you.
More in the README.md · main · Michael K Johnson / ReturnedEnergyDump · GitLab — that repo has complete KiCad 6 files for the board, gerbers and drills, and datasheets for most if not all of the components.