Pulse Motors: MHOP #7: Dwell and Timing Strobes Video Test

Here’s a test video to see if the LED strobes can make it past the transcoding process and show up to the final viewer.

I used the second op-amp in the TL082 package, simply reversing the inputs, taking the reference voltage from the same potentiometer. The high-impedance and sensitivity of the JFET input stage of the TL082 makes it very versatile with ease of paralleling inputs.

The two outputs of the op-amps then correspond to the beginning and the ending instants of the ON pulse to the mosfet gate, which then controls the Drive Coil current.

The DPDT switch allows the input of the divide-by-four 4017 chip to select either of the op-amp outputs, at the same time switching to the appropriate strobe LED (Green to indicate the start of the pulse, and blue to indicate the end. Red didn’t show up well against the red rotor body.) The same 555 pulse shortener thus serves for both strobes.

Later I’ll implement a second 4017 and use a 556 for two pulse shorteners, and then the two strobes can be on simultaneously. This will allow full realtime monitoring of the exact timing and dwell angle while the motor is running, without any external instrumentation.

If the strobes are not desired or needed, the single op-amp is all you need for full control of the drive pulse duration and timing.

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