Mechanical Timer

 This article is about mechanical timer made from

an mechanical digital counter from an old

VCR (Video Cassette Recorder).

Figure 1: Mechanical Timer

You can see how my mechanics timer spins in this video:

Tools

pliers, cross screwdriver.

Optional tools: wire stripper, soldering iron.

Components and Parts

old counter, old motor, drive belt or rubber band, screws, piece of wood, a metal wire (2 mm for structure and 1 mm for securing the wires), power source.

You start with 3 V and then change to 6 V and later to 9 V battery if the motor is still not spinning. However, there is a risk that you can burn the motor. You might need to check the motor maximum voltage specifications. You can tell that the motor is a high power motor if the motor is bigger, the rotor heavier and thus is not spinning as smoothly, thus estimate the maximum voltage. 3 V motors are smaller and easier to spin than high voltage motors.

Optional components: solder.

Step 1: Assembly

I secured the motor to a piece of wood with two screws. Then I attached the counter to piece of wood with a 2 mm metal wire. The last step was securing the wires with a 1 mm metal wire because loose wires can fall off. Do not pull the wires hard. You might stretch and short the positive and negative terminals.

Figure 2: Side View.

Figure 3: Timer Stand.

If you reverse the voltage polarity than the counter will spin backwards.

The motor that I used is a high torque motor, although you do not need much mechanical power at all for this counter. It is very smooth running. However, not all motors can drive this counter due to the high pressure of stretched the drive belt.

You can see in the photos that there is a capacitor across the motor. This capacitor was already attached to the motor when I removed it from an old VCR many years ago. Capacitors are used for power factor correction (improve circuit power efficiency) and filter the noise generated by the motor than can interfere with operation of other appliance in your home.