This is speed motor controller circuit of 12V DC motor. as SCR DC motor speed control circuit using IC-CMOS. You can adjust the speed of rotation of the spindle motor from 5-60 cycles per minute.
How does it work
To begin with, the 12V AC voltage from the Secondary of transformer comes to bridge diode-BD1. It rectifies from AC (Alternating Current) to DC (pulsed DC).
SCR DC motor speed control circuit using IC-CMOS
This can use for DC motor and SCR1—The SCR need to uses DC to A-K lead—. Which it uses just the pulsed DC only.
But we also use digital IC.
Second, we use one nand gate CMOS-IC, CD4081. It requests a stable power supply to pin 14. The D2 gets the pulsed DC to filter to smooth DC current with C2-220uF.
The pin 1 gets the pulsed DC directly. And the other into pin 2. Next, The VR1, C1, and R1 are the phase shift circuit to delay the pulse DC to slow down.
After that, the pulsed DC from pin 3 to triggers the gate of SCR1 turns on.
The working of SCR like switches on-off the pulsed DC to the motor, makes it rotate. The Speed of the motor can adjust by VR1.
If pulsed DC has “high” state more than “low” state. It makes more current to the DC motor, it rotates very fast.
But in the opposite way, the “high” less than “low” state. It rotates too slow.
The D1 prevents the noise from the motor.
The D3 is a reverse-voltage protection of motors. This can cause circuit damages.
If the circuit uses to the high power motor. You need to install a large heat sink to BD1, D1, and SCR1. Because they are very hot, may damage.
How to builds
This project is easy because use a few parts. For faster to build if we assemble this circuits in the Universal PCB in Figure 2 is components layout for a guide.
The components lists.
IC1___CD4081___CMOS Nand gate IC
SCR1___SCR-C106D or equivalent
BD1____Bridge Diode 6A 200V
D1_____1N5401___3A 100V diode
D2,D3__1N4004___1A 400V Diode.
T1_____Transformer 3A 12V
C1_____1uF 16V Electrolytic capacitors
C2_____220uF 16V Electrolytic capacitors
Other circuits are recommended.
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