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relay noice reset pic microcontroller

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abilashjoseph

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hi,
i am made a microcontroller circuit having relays, in my circuit the GND and NEUTRAL are shorted,

problem is that the controller is reset when the relay turn off, the relay switches 230VAC, what is the reason,

any circuit for avoiding this? please help me.

thanks in advance..
 

HI, Put a diode over the relay coil !.


--------------------------------------------- +
| |
D| __|__
/ \ |____| RELAY COIL.
| |
|----|________ MICROCONTROLLER
 
sir,
thank u,
i already used a uln2003 relay driver. and also i tested with a diode across the relay coil, the same problem exist. and i use a 100uf electroletic capacitor across the coil.
 
it's a common problem,

first use free wheeling diode on 2003(pin9,same V+ as relay),and dont forget to declare all inused port
(i put all inused port to output and low)

and cap .1 near V+ of pic
 

Hi Friend

I have same problem with PIC12F683 in past.

To solve this problem,
Put one 0.1uf capacitor and one 220uf/16V electrolyte capacitor parallel between Vcc pin and GND pin of Microcontroller.
The pcb track between capacitor and pin keep as short as possible.

Second solution.
Isolate relay from Microcontroller using PC817 optoisolator.
and also Isolate Microcontroller VCC and Relay coil supply.

Hope this is help you.
Shyam
 
try to put a small capacitor across relay,
i thing you are switching ac volt, try to switch at zero crossing
 

8051 microcontroller is reset on surge

hi.
i am using 89v51rd2 ic ,with one 12v relay also.....
my controller is getting reset when i am switching on any other switch on the 230v supply board, where i have connect my smps.


in one other with project my same ic, functioning of relay is resetting controller

plz give me some solution for boath project.
its urgent.
thanks in advance..........
 

Hi,

You can refer my post no. #6 in this same thread.
You can also use Optoisolator and triac combination to control 240v like

89v51rd2 ==> Moc3021 ==> BT136 ==> 240v AC load.

This combination without micro widely used in electronics fan regulator.

Hope this is help you.
Ghanshyam
 
Last edited:

Use an opto-coupled TRIAC driver MOC302x series.It will solve your problem :)
 

When Power ON-OFF frequently then my PIC Micro-controller does not work properly, some time it needs to turn OFF and give time to reset fully then turn ON.

Also during OFF, it turn OFF then it turn ON for a moment, then again turn OFF. It makes problem eeprom and port status.

How can I solve these Problems?

In my PIC Micro-controller, I use Normal power supply using Transformer (12V-0V-12V), diode(1N4007), Capacitor 1000uF, 25V and 104(0.1uf) and finally LM7805 .
 

PIC has 10 uF and 0.1uF capacitors across its power pins and close to PIC ?
 

What is your load,I mean what is connected at relay output?Do you have problem without load or with load condition?as asked earlier show us your schematic.You can solve the problem with the snubber circuit or MOV at relay output.
 

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