My circuit it's a counter , contain tow counters and the output of this counters connect with ( IC) comparator (74682) and the output of this comparator connect with transistor(NPN) (3904) , the collector of transistor connect with relay , contact of relay connect with contactor, contact of contactor connect between 3- phase and motor.

How to action:

1- If I need any number from 1 to 9 in 7- segment (1) I appoint this number from button S1 .
2- press in button (start) the motor rotate , any revolution the sensor exit signal to clock 2 .
3- If the two number in 7- segment 1 and 7- segment 2 equal the (IC 74682) exit signal to (NAND ) gate and exit signal from Q' to pin number (3) in counter 2 , this counter rest .

I built this circuit , If I work this circuit without contactor and motor , a circuit work good without error , but I found problem , this problem :
If I connect a contactor and motor the point number in 7-segment (1) change alone.
What I can make to removal this error.

Note: If you found mistake in grammar I hope excuse me because the English language not my mother language .

Thank you.

Image number 1 is a bluck diagram



Image number 2 is a circuit

 

Please do additional test.

Disconnect motor cable but keep contactor operating. Is the problem still there?

__________________
L.Chung

 

thank you (eblc1388)

I am try a circuit without a motor , but this problem is same .

 

You should place a diode across the DC relay coil to bypass the back emf, which I don't see in your circuit.

If by operating the contactor alone the digit is still changing, then you need to move the contactor further away from the circuit to lessen electrical interference. Also it is a good idea to place a (100 ohm+0.01uF) suppressor across the relay contact to suppress the arcing when the relay contact opens.

Place all your circuit inside an earthed metal box also helps.

If all else failed, I would try using a Solid State Relay to drive the contactor directly in the hope to reduce switching interference.

__________________
L.Chung

 

I am connecting a diode across the DC relay coil (free wheeling diode ) , but I am forget draw this diode in a circuit .

I am try this , but problem same.

Not the digit change in 7-segment 1 only, but change in 7-segment 1 and
7-segment 2 alone.

Now place all my circuit inside in plastic box without a contactor outside of plastic box .

I think this option it’s best.

thank you.