Release Sw1 and press SW2 and +12 volts is supplied to the '+' side of the motor while the negative side is grounded through SW1. The motor will spin at full speed say counter-clockwise. If we press SW1 the NC contact opens and the NO closes supplying +12 volts to one side of the motor while the other side is still grounded through SW2. In its normal state, both motor connections are grounded through the switches. A DC motor is connected between the two commons. The normally closed (NC) contacts are grounded and normally open (NO) contacts are connected to +12 volts. In figure 1 we have a very basic H-bridge using two spring-loaded, single-pole, double-throw switches. One of the most common solid-state controls is known as the H-bridge. Reverse the voltage, the direction of rotation reverses. Their direction of rotation is dependant upon the polarity of the applied voltage. Permanent magnet DC motors have been around for many years and come in a variety of sizes and voltages. The other is a P-channel device rated at 55V and a RDS(on) of 0.02 Ohms max.Īlso see Test Power MOSFET Transistors, Results, Observations The IRFZ44N is an N-channel device rated at 55V and RDS(on) resistance of 0.032 Ohms max. I found two MOSFETs that work at 3.3-volts. Many micro-controllers today are using 3.3-volt Vcc. MOSFETs can be connected in parallel for high power and lower ON resistance.Īll of this is addressed in the following videos and links at the bottom of the page. The newer material addresses these issues but is still based on material below. The 20-volt limit is due to the Vgs (voltage gate-source max) of the MOSFETs. Using the newer transistors the operating voltage is 5V to 20V. The information below is 100% relevant today. It is just as easy to use combinations of MOSFETs, bipolar transistors, and even insulated gate bipolar transistors. This depends on motor voltage and current that determines the H-Bridge construction. Build Power MOSFET H-Bridge for ArduinoĪny number of solid-state switches can be used for H-Bridges.Test Power MOSFET Transistors, IGBTs Results, Observations. Their low on resistance delivers more power to the motor. My recent tests have proven these devices work far better. This wastes power and the p-channel in particular runs hot. These devices are dated and have a high turn on resistance or rDS(on). I no longer recommend using IRF630 n-channel and IRF9630 p-channel MOSFETs.

Forward and reverse motor h bridge