Pic reseting when switching mains current with relay

[Dave]

lsteele, I notice that your relays are powered by 5 volts. Is the source of the 5 volt supply the same as the PIC? If so I would have a separate supply for the relay source and a separate supply for the PIC. From what I have seen in the past you are working with electromechanical devices that have magnetic coupling and when you are opering the contacts the field is being coupled to the 5 volt supply the micro it is being powered from. If this supply for the relay source was separate and the ground paths are correct I see no problem with the operation of the relays switching the mains.

Dave Purola,
N8NTA

[sayzer]

I meant to say use BOD_OFF.

Most likely!

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[shahidali55]

hello ,
I'm having a similar problem.
I have made a 7seg LED clock (PIC16F628 @ 4Mhz).
The clock resets when i switch on the tube light in my room.
The clock and the tube a not linked to one another in any way.
I was using a wall adapter before to power it, but even after i replaced it with a 9 volt battery, the clock still resets when i switch the tube on.
What could be the reason for this ? ? ?

[mister_e]

without schematic and code it's hard to say.

[shahidali55]

This is the schematic . . .
http://www.josepino.com/pic_projects...clock_4050.gif

I have used transistors instead of the 4050 IC's .
I have used PIC16F84A and not PIC16F628.
I dont think its the code error cause if i keep the clock in another room, it doesn't reset.

[malc-c]

Not sure if it has any bearing on this but I built a sequential light display that flashed mains light bulbs (240v) and didn't suffer any issues of the PIC resetting. I used solid state relays for the mains switching which are opto isolated from the mains. The only issue is that they aren't as cheap as traditional relays.

Maybe you could use an opto isolator and thyristro / triac driver to do the same thing only a bit cheaper. Something like


(ommit the 741 - as it wouldn't be needed for your circuit)

[mister_e]

shahidali55

Any capacitor close to your PIC and close to your 7 Segment display?

Where are the current limiting resistor for the display.

3.6-5.5V is that right?

How about your configuration fuse?

How the final 'gizmo' looks?

Sure there's something that pickup noise. Is the software take care of this poor unconnected PIN 4?

malc-c

I think you misread something or... could be me too