2016-12-06 (Tu) Clockwork Theremin

A new H-bridge arrived and was connected. This model was only built to control one motor but it could easily handle the current. It was rated at 43 amps so the peak current, less than 20 amps, shouldn’t provide any problems.

New H-bridge connected

As soon as it was connected properly, which took longer than it should have, it was clear this motor controller was different from the previous model. When 40% duty cycle was applied the motor spun aggressively instead of just beating inertia. The starting duty cycle was lowered and a mere 8% was enough to move the motor. 8% was approximately one volt. Hopefully, this meant that the initial speed was only 1/12 of the final speed capable with this motor.

Meter connected to read motor voltage

An animation was made of the gears moving. This animation was actually a ping-pong loop. The actual recording was the gears moving in one direction but the animation reverses the frames to give a smooth animation. The gears were extremely loud and the motor made a high-pitch sound, probably the PWM frequency.

Gear animation

The high speed movement of the gears caused the left-handed nut on the motor shaft to loosen more than once. A nut driver was kept nearby to reattach it as necessary. It will be important to use a chemical thread locker or at least a mechanical lock washer.

Nut driver to retighten nut

Parts list:

The rest of the posts for this project have been arranged by date.

First time here?

Completed projects from year 1.

Completed projects from year 2.

Completed projects from year 3.

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2016-12-06 (Tu)