Snubber and other Filters

Hai,

I am building a circuit based on atmel, the circuit will have to trigger relays. The relays used are 5v Relays ( The small cube shaped ones ). In the initial prototype i Noticed that arduino resets when relay unlatches. I want the circuit to be rock solid. So Have done following things

Relay is turned by transistor which is triggere by optocoupler.
The Relay Board and main circuit is powered from 2 different Smps.
I have added a flyback diode IN4004 on relays.
I will be using a Twisted pair cable from mainboard to Relay Board

The relays will be switching 1) 200V DC motor with current consumption of under 0.5 Amps
2) 240V Solenoid Valve
3) 240V 2 Amps AC motors
and many inductive Appliances ( not anything that consumes more than 2 amps )

What are the other things i should add to the circuit.
Should i add snubber across relay coil and also across load terminals ?.
What are the C and R values i should choose for each..


Adding MOV is bad i guess, Because i will be giving the product to an end customer and from what i have read online, MOV has a lifespan.


i Want the circuit to be rock solid. What other suggestions do you have

The relays used are 5v Relays ( The small cube shaped ones ). In the initial prototype i Noticed that arduino resets when relay unlatches.

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Please do not do any of this: You are using the same 5V bus shared with relay and other electronic circuits. In addition the Arduino board is NOT not a good choice to be used in systems prone to EMI like this; Its PCB routing is scattered, in addition to the stacking of the shields acting as antennas. To make it worse, solenoids are strongly inductive components, and I would also consider implementing some suppression locally, near to their terminals.

andre_teprom said:

Please do not do any of this: You are using the same 5V bus shared with relay and other electronic circuits. In addition the Arduino board is NOT not a good choice to be used in systems prone to EMI like this; Its PCB routing is scattered, in addition to the stacking of the shields acting as antennas. To make it worse, solenoids are strongly inductive components, and I would also consider implementing some suppression locally, near to their terminals.

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No Electronic circuitry and relay circuit uses 2 different rails. (They are 2 indipendent 240V to 5V smps )

I Will be using ATMEGA2560AU in my circuit with lots of decoupling capacitors.


Yea i want to suppress the noise locally, so what are the ways to do that..

i want to suppress the noise locally, so what are the ways to do that.

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I usually put only one RC array that is pretty sufficient, and I admit I do not make any further quantitative examination to assess the attenuation achieved; I rely solely on the calculation. Anyay for your case on which the problem is actually happening I believe it would also be advisable to add a MOV there in addition with the snubber.

andre_teprom said:

I usually put only one RC array that is pretty sufficient, and I admit I do not make any further quantitative examination to assess the attenuation achieved; I rely solely on the calculation. Anyay for your case on which the problem is actually happening I believe it would also be advisable to add a MOV there in addition with the snubber.

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Can you help me out with the rough values of R and C. and are you talking about placing R and C across relay coil or relay contacts?