The circuit we present makes use of an H-bridge in an anti-phase control in order to obtain changes in the speed of a two-way motor.

With the transistors used the maximum recommended current is of the order of 1 A, but higher current capacity transistors can be used.

The base of the circuit is an oscillator with the active duty cycle drawn up around one of the doors of a 4093.

The other three ports are used to apply opposite phase signals to the H-bridge which controls the motor.

One drawback of this circuit is that at the 50% active duty cycle, which corresponds to the motor stopped, the motor remains consuming power and depending on the application it can oscillate.

In Figure 1 we have the complete diagram of the speed control PWM with rotation inversion.

 

   Figure 1 - Complete control diagram
Figure 1 - Complete control diagram

 

 

The printed circuit board for the assembly is shown in Figure 2.

 

   Figure 2 - Printed circuit board for the assembly
Figure 2 - Printed circuit board for the assembly

 

 

Transistors must be fitted with heat sinks and their position, as well as the integrated circuit, must be observed.

 

The resistors are 1/8 W with any tolerance and the capacitor C1 must have its value chosen according to the motor, so that it does not vibrate too much.

 

For a better control, a double potentiometer can be used, so that when one section has increased resistance the other has decreased it, according to the connection shown in Figure 3.

 

   Figure 3 - Using double potentiometer
Figure 3 - Using double potentiometer

 

 

 

Q1 to Q4 - TIP120 - NPN power Darlington transistors

CI-1 - 4093 - integrated circuit

D1, D2 - 1N4148 - general purpose diodes

D3, D4 - 1N4004 - silicon rectifier diodes

R1 - 22 k ohm - resistor - red, red, orange

R2 - 2k2 ohm - resistor - red, red, red

R3 to R6 - 10 k ohms - resistors - brown, black, orange

P1 - 100 k ohm - potentiometer

C1 -1 - 220 nF - polyester or ceramic capacitor - see text

C2 - 1000 uF - 16 V - electrolytic capacitor

 

Miscellaneous:

Printed circuit board, heat sinks, power source or battery, wires, welding, etc.

 

 

Datasheets


N° of component