MOSFET DC Motor Driver: Circuit, Measurements and Online Simulator

To build this MOSFET DC Motor Driver circuit you need a bench power supply, a 5 A analog ammeter, a toggle switch, a 10 kΩ resistor, an IRLZ44N N-channel MOSFET, a DC motor and a 1N4007 diode. A logic-level IRLZ44N switches a DC motor from a 12 V supply; a 1N4007 across the motor catches the inductive kick. The ammeter shows the start-up surge. Make the 11 connections in the wiring table, press Run, and and flip the switch: the ammeter needle jumps, then settles as the motor spins up and its back-EMF grows.

Open this circuit in the free Electronics bench simulator

Parts list

Qty	Part	What it does
1	Bench Power Supply	Set the voltage and a current limit. It holds the voltage (CV) until the load wants more than the limit, then holds the current (CC). + and − float; GND is earth.
1	5 A analog ammeter	A moving-coil panel meter with a shunt: wire it in series, current entering +.
1	Toggle Switch	An on/off switch between its two terminals. Flip it while the circuit runs.
1	10 kΩ resistor	Limits current. 220 Ω in series with an LED; 10 kΩ as a pull-up or pull-down.
1	IRLZ44N N-channel MOSFET	Voltage-controlled: raise G above S by more than the threshold and D–S conducts. The IRLZ44N switches amps from a 5 V pin.
1	DC Motor	A small brushed motor (~8 Ω). Its back-EMF grows with speed, so the current is high at start and falls as it spins up. Drive it through a transistor or MOSFET, never straight from a pin, with a flyback diode across it.
1	1N4007 diode	Conducts from A (anode) to K (cathode, the striped end) once about 0.7 V is across it; blocks the other way.

Wiring

#	From	To
1	Bench Power Supply +	5 A analog ammeter +
2	5 A analog ammeter -	DC Motor +
3	DC Motor -	IRLZ44N N-channel MOSFET D
4	IRLZ44N N-channel MOSFET S	Bench Power Supply -
5	Bench Power Supply -	Bench Power Supply GND
6	1N4007 diode K	DC Motor +
7	1N4007 diode A	DC Motor -
8	Bench Power Supply +	Toggle Switch 1
9	Toggle Switch 2	IRLZ44N N-channel MOSFET G
10	IRLZ44N N-channel MOSFET G	10 kΩ resistor leg 1
11	10 kΩ resistor leg 2	Bench Power Supply -

Step by step

Open the electronics bench. Open the BitForBytes Embedded Lab in your browser. A circuit with no microcontroller runs on the analog bench: no install or account is needed.
Add the parts. Add a bench power supply, a 5 A analog ammeter, a toggle switch, a 10 kΩ resistor, an IRLZ44N N-channel MOSFET, a DC motor and a 1N4007 diode from the parts palette (Instruments, Power, Passive and Semiconductors).
Wire 1. Connect Bench Power Supply + to 5 A analog ammeter +.
Wire 2. Connect 5 A analog ammeter - to DC Motor +.
Wire 3. Connect DC Motor - to IRLZ44N N-channel MOSFET D.
Wire 4. Connect IRLZ44N N-channel MOSFET S to Bench Power Supply -.
Wire 5. Connect Bench Power Supply - to Bench Power Supply GND.
Wire 6. Connect 1N4007 diode K to DC Motor +.
Wire 7. Connect 1N4007 diode A to DC Motor -.
Wire 8. Connect Bench Power Supply + to Toggle Switch 1.
Wire 9. Connect Toggle Switch 2 to IRLZ44N N-channel MOSFET G.
Wire 10. Connect IRLZ44N N-channel MOSFET G to 10 kΩ resistor leg 1.
Wire 11. Connect 10 kΩ resistor leg 2 to Bench Power Supply -.
Run and measure. Press Run and flip the switch: the ammeter needle jumps, then settles as the motor spins up and its back-EMF grows.

Lab sheet

// Electronics bench: MOSFET low-side switch
//
// Gate: switch to +12 V, 10 kΩ pull-down so it turns off cleanly.
// Drain to the motor, source to 0 V. Diode cathode to +12 V, anode to the drain.
// At standstill only the winding resistance limits current (12 V / 8 Ω);
// as the motor speeds up, back-EMF opposes the supply and the current falls.

What to try

Press Run and flip the switch: the ammeter needle jumps, then settles as the motor spins up and its back-EMF grows.

Frequently asked questions

How do I wire the MOSFET DC Motor Driver circuit?

Make 11 connections: Bench Power Supply + to 5 A analog ammeter +; 5 A analog ammeter - to DC Motor +; DC Motor - to IRLZ44N N-channel MOSFET D; IRLZ44N N-channel MOSFET S to Bench Power Supply -; Bench Power Supply - to Bench Power Supply GND; 1N4007 diode K to DC Motor +; 1N4007 diode A to DC Motor -; Bench Power Supply + to Toggle Switch 1; Toggle Switch 2 to IRLZ44N N-channel MOSFET G; IRLZ44N N-channel MOSFET G to 10 kΩ resistor leg 1; 10 kΩ resistor leg 2 to Bench Power Supply -.

What parts do I need for the MOSFET DC Motor Driver?

A bench power supply, a 5 A analog ammeter, a toggle switch, a 10 kΩ resistor, an IRLZ44N N-channel MOSFET, a DC motor and a 1N4007 diode.

Can I simulate the MOSFET DC Motor Driver online for free?

Yes. The BitForBytes Embedded Lab solves the circuit in time, the way SPICE does (nodal analysis with real diode, transistor and capacitor models), and gives you a bench power supply, function generator, oscilloscope and multimeter to measure it — free, in the browser.

What does this circuit show?

A logic-level IRLZ44N switches a DC motor from a 12 V supply; a 1N4007 across the motor catches the inductive kick. The ammeter shows the start-up surge.