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555 timer circuit to control motor

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Krishna Patil

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To control 0.5 HP motor i did this circuit . Using PCB relay , 555 is getting heated up sometimes and relay switching abruptly. Is this Circuit correct ?
 
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I think you are missing the fly back diode accross the coil. You may take a look at this solution with an integrated relay driver: https://ichaus.biz/appnote_industrial .

Enjoy your design work!
 

It depends on the specification of the relay. Overheating the 555 could mean the output is overloaded.

Enjoy your design work!
 
Check 555 datasheet whether it can give that much of current. Also measure the current that drawn by relay; so you know it exactly. When it reaches upper-limit, it may heat up more. But for the safety, it's better if you can use a transistor to power the relay. use a transistor that can handle 3,4 time higher current that required by relay.
 
ya , i checked datasheet and found 200ma is max sinking capacity of 555 timer. I'm using 400 ohm coil PCB Relay .

I checked Current drawn it was 30 ma when i checked it using CFL at Relay load .

But when i connect to AC Motor 230v it behaves abruptly . For some time circuit works proper , suddenly 555 triggers at wrong position .

I'm using Freewheel diode and one extra diode to properly sink current from coil .

cirucit.png
 

AC motor draws high current at start; and that leads to drop the voltage to your 555.
You must be taking power to 555 from AC line. (through a step-down transformer, rectifiers...)
That is why it worked for CFL.
Supply power to 555 from any other source and check. After that we can improve your power supply unit.
 
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