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Step 4Electrical Components
The electrical components consist of the following:
1. Start the motor upon sensing motion
2. Stop the motor when the motion stops
3. Reverse the direction of the motor when the jaw is completely open or closed.
For an electronic enthusiast designing a motion sensor probably will be a breeze. However, I had to find a cheap solution without making it a big project like the motor shaft. I picked up a cheap motion detection light kit from the neighborhood Home Depot for $15. You may have seen the use of these lights outside the garages. There was one small challenge involved. The unit, as shipped from the factor is supposed to turn on or off a 110 Volts AC source. If you look at my circuit diagram, I needed the motion sensor to supply me a normally open (NO) push button type output. This needed some hacking. So I opened up the sensor unit. The sensor unit is rather simple. The electronics turns on or off a relay. The relay is a normally open single contact relay. On the circuit board, the hot wire (Black) was connected to one end of the relay switch. The other end came out as a red wire. Obviously when the motion is detected the relay coil turns on the switch and provides juice through the red wire. I carefully cut the laminated copper strip on the printed circuit board, which was connecting the hot wire to one end of the normally open relay switch. Using a multi-meter, I checked and re-checked the contact to make sure they were not connected. I soldered a green wire to the cut side of the relay switch, and brought it outside the sensor unit. So, now the unit has four wires coming out of it. The black and white wires provide the 110V AC to the unit to make it work. The red and the green wire provide the open and closed switch contacts, which I needed to trigger the starting of the motor.
WARNING: I must warn the readers, what I did was very risky. One mistake, and you will land up getting the hot side of 110V AC coming out of the green wire causing electrical shock and possible death.
1. Start the motor upon sensing motion
2. Stop the motor when the motion stops
3. Reverse the direction of the motor when the jaw is completely open or closed.
For an electronic enthusiast designing a motion sensor probably will be a breeze. However, I had to find a cheap solution without making it a big project like the motor shaft. I picked up a cheap motion detection light kit from the neighborhood Home Depot for $15. You may have seen the use of these lights outside the garages. There was one small challenge involved. The unit, as shipped from the factor is supposed to turn on or off a 110 Volts AC source. If you look at my circuit diagram, I needed the motion sensor to supply me a normally open (NO) push button type output. This needed some hacking. So I opened up the sensor unit. The sensor unit is rather simple. The electronics turns on or off a relay. The relay is a normally open single contact relay. On the circuit board, the hot wire (Black) was connected to one end of the relay switch. The other end came out as a red wire. Obviously when the motion is detected the relay coil turns on the switch and provides juice through the red wire. I carefully cut the laminated copper strip on the printed circuit board, which was connecting the hot wire to one end of the normally open relay switch. Using a multi-meter, I checked and re-checked the contact to make sure they were not connected. I soldered a green wire to the cut side of the relay switch, and brought it outside the sensor unit. So, now the unit has four wires coming out of it. The black and white wires provide the 110V AC to the unit to make it work. The red and the green wire provide the open and closed switch contacts, which I needed to trigger the starting of the motor.
WARNING: I must warn the readers, what I did was very risky. One mistake, and you will land up getting the hot side of 110V AC coming out of the green wire causing electrical shock and possible death.
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