This circuit has 2 input and if both it’s input is “1” (+12 volt) What will happen?, If some input voltage is “0” (such as input A) transistor T5 will conduct a current and as cause to transistors T1 and T4 also conducts, and makes the DC motor running In one direction. When it comes this time, we will explain what is part of this circuit that saving.
-You will notice that.Each pair of transistors in bridge is controlled by only one transistor driver. This thing not only saves equipment. It also saves energy. Which is opposite to the two transistor driver. When the transistor T5(BD140 or BD136) conduct the T1(BD242) work with, the current flow of T1 by controller of T5 go to base of T4 cause T4(BD241) also conduct. This means that we use the base current of T1 and T3(BD242). In driving the T4 and T2(BD241), respectively, which makes we have drive common circuit.
-There are two other components that contribute to that are diode D5 and D6 Which will be described only briefly as follows the D5 and D6 are Be the parts to makes sure that Will not be damaged. If both inputs are “0” at the same time. For example IF input A has voltage is 0 volts, T1 and T4 will conduct both, and a anode of D6 will be connected to a 12 voltages.
-If the input B is “0” with T6 (Including T2 and T3) Will not be able to condoctor. Because the base leg of T6(BD140 or BD136)is connected to the positive voltage. So input B will be triggered just continue on. After the voltage at A is “1” only, and conversely for the other one half.
-We can use the pulse width modulation (PWM) of the speed control of DC motor. That is if the input signal at input A or B is a discrete signal. The pulses can be wide, it can be used to control the speed of the motor. If the motor rotates quickly narrow pulses. If you want to get the motor to work harde, maybe instead of T1-T4 with a Darlington, Which will flow rate is sufficiently high.
-Input circuit of working at logic “0”. Therefore, it is suitable to drive a logic-level TTL. If the power supply for motors greater than 5 volts. We must use the TTL gate that has an open collector output. The maximum current that motor will running is 1 amps and the current undisturbed is almost zero.
DC Motor Control with TIP31
Here, S1 and S2 are normally open , push to close, press button switches. The diodes can be red or green and are there only to indicate direction. You may need to alter the TIP31 transistors depending on the motor being used. Remember, running under load draws more current. This circuit was built to operate a small motor used for opening and closing a pair of curtains. As an advantage over automatic closing and opening systems, you have control of how much, or how little light to let into a room. The four diodes surriunding the motor, are back EMF diodes. They are chosen to suit the motor. For a 12V motor drawing 1amp under load, I use 1N4001 diodes.