I made this circuit to drive a DC linear actuator motor. The speed is controlled by the logical impulse voltage source. To change the speed, just change the duty cycle of the logic source in the top right part of the schematic.
The direction is controlled by the switch/MOSFET on the left side of the schematic. The switch controls the two relays representing a double pole double throw (DPDT) relay.
This particular actuator uses a potentiometer to give feedback to determine position. The feedback can be adjusted by changing the potentiometer wiper position in the bottom right part of the schematic. Note that "D" in the ADC is the most significant digit.
Parts used for this project:
1. 12V linear actuator with feedback
https://www.amazon.com/gp/product/B00Q74IMLM/ref=ox_sc_act_title_7?smid=ATVPDKIKX0DER&psc=1
2. 3.3V logic power mosfets
https://www.amazon.com/Jekewin-N-Channel-Power-Mosfet-220/dp/B071Z98SRG/ref=sr_1_12?crid=3CO8WBGV6M39Q&keywords=power+mosfet+raspberry+pi&qid=1653082089&s=industrial&sprefix=power+mosfet+raspberry+pi%2Cindustrial%2C104&sr=1-12
3. 12v DPDT Relay
https://www.amazon.com/Electromagnetic-Socket-Mechanical-Indicator-LY2N-J/dp/B07T12WLMT/ref=sr_1_8?crid=20CVU4XQZB21X&keywords=dpdt%2Brelay&qid=1653082238&sprefix=dpdt%2Brelay%2Caps%2C139&sr=8-8&th=1
4. raspberry pi controller
https://www.amazon.com/Raspberry-Model-2019-Quad-Bluetooth/dp/B07TD42S27/ref=sr_1_3?keywords=raspberry+pi&qid=1653082182&sr=8-3
5. Analog to Digital Converter (for distance feedback)
https://www.amazon.com/gp/product/B00NAY3RB2/ref=ox_sc_act_title_5?smid=A2GTSJRNFEVVSP&psc=1
Notes: The constraints of this project was that I needed to use a raspberry pi, otherwise I would have used the 5V logic of an Arduino. This makes the power MOSFET's important so that they can turn on with the raspberry pi's 3.3V logic. Also because raspberry pi's don't have a built in ADC, one has been included in the parts list. The feedback potentiometer can be driven through the raspberry pi's onboard 5V pin.
created by Nathan Dickson
Aerospace Electrical Engineer
