2016-11-23 (W) Clockwork Theremin

Many motors will have a nameplate that lists their Voltage (V), Full-Load Amperage (FLA), current type (AC or DC), if they're AC the nameplate will list the number of phases (PH or Φ) and other information for its application. The motors used in this project had a paper sticker with "12V" and nothing else so matching it with a power supply has been difficult. A terminal strip, a switch, and a current meter were hooked up so that different supplies could be tested.

Four videos were taken to demonstrate different 12V power supplies. The first video was to demonstrate a 3A power supply ordered specifically for this project. Two supplies were ordered with the intention of using one for each motor. These supplies were underpowered for the task. The motors drew more than the available three amps and this caused the little supply to "hiccup" ("hiccough") and temporarily go into a fault state. Then, the supply would reset itself and repeat the fault state.

Video demonstration of 3A open-frame power supply

The second power supply was only rated for two amps but it was a close-frame industrial power supply. This supply didn't fall into a fault state but it would not deliver more than two amps for longer than a second. When the motor was starved for power it would turn and eventually achieve maximum speed but it took a long time.

Video demonstration of 2A closed-frame power supply

A twelve-volt battery used to jump-start automobiles was connected to the circuit. The battery had no current limiting circuitry, or even a circuit breaker or fuse. As far as the little motor was concerned, there was infinite current available. This allowed the motor to start instantly and achieve maximum speed very quickly.

Video demonstration of 12V battery

Another open-frame power supply arrived before testing completed. This time, the power supply was rated for five amps which should have been enough to cover the draw seen by the meter previously. There was enough power to spin the motor but it had a slow uptake and the light on the power supply dimmed dangerously.

Video demonstration of 5A open-frame power supply

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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2016-11-18 (F)