AC Motor Speed Controller using U2008B

  • Rajkumar Sharma
  • medium
  • Tested
  • SKU: EL48023
  • Quote Now


This is a low cost, current feedback phase control AC motor driver based on U2008 IC. The U2008B is designed as a phase control circuit in bipolar technology. It enables load-current detection as well as mains-compensated phase control. Motor control with load-current feedback and overload protection are preferred applications.


  • Supply Input:  230V AC
  • Load: up to 500W (Triac Requires Heat sink for Higher Load)
  • Jumper J1 Selection: A-Load Current Compensation or B-Soft Start
  • PR1: Preset for Phase Control ( Ramp Current Adjustment)
  • P1 : Potentiometer Set Point



Parts List


U2008B Datasheet

Please follow and like us:
Pin Share


Notify of

Inline Feedbacks
View all comments
Ajay Desai

I would like to know the cost of this kit and it’s availability details.

Ajay Desai

I need about 25 pieces. It is not available on koteq. Let me know availability in Hyderabad

kamaleu norbert

need 10 pcs of this speed controller


Soft start does not work properly even with resistive load. Counter-effect. It starts at full speed and then turns to the set value of P1. Direct launch does not work at all. Could the problem be in U2008?


this schematic isnt for load current compensation… if you look at scheme in datasheet, you ll see that its for soft start


is there a way to control this by Arduino, so that It can give us different speeds at a programmed time ??

David Reynolds

Given that a potentiometer controls the phase angle I would say that it would work from arduino. You would need to isolate the arduino with an optocoupler transistor use variable PWM to feed the opto led, and use the output on to pin 3 leave the C4 in place and put a pull down resistor in the opto output to pin5, I guess between 1K and 10Kohm.
Do not forget it is very dangerous messing with mains voltages, do not do it if you are not sure.
Dave R.

Claudemir Vernini

How can I adapt this circuit to a voltage of 127 volts, being Neutral and Phase?

David Reynolds

Reduce the R1 resistor to around 11K if you are only using 115V.AC.

Dave R.

Claudemir Vernini

Thank you so much, Dave. Your help is of great value.
I want to get the components as soon as possible

David Reynolds

Claudemir, if you are building the circuit on your own board, you could use a reactive feed to power it.
By replacing the R1, power resistor with an X2 RC cap of 0.22uFx100 ohm and placing a diode across it facing the opposite way to the D1.
This would reduce the heat wasted in the resistor. I have used this method for other mains control chips, in the past.
Just a thought.


Claudemir Vernini

Hi Dave!
It’s noted!
I ordered the U2008B from China, since in Brazil it’s hard to find at a modest price.
It should arrive around two months …
In the meantime, I will make a new PCI card according to your suggestion.
Thank you very much.

Gheorghe Ivan

Bello !
I never used this ic before.
Is this ic a kind of microcontroller?

Gheorghe Ivan

Thank You!


Is this kit still available? The web link does not work. I would like to purchase one

John Claud


I would like to ask, does this kit able to control the speed of the household PSC motor?

and, I would like to know about the soft-start, does it start from 0 to maximum or to the set point of the potentiometer? and, can I sense the load current while using the soft-start feature?

my goal is to use his IC and control the speed from Arduino while attaining a soft-start, and being able to see the load current + voltage.


TOP PCB Companies