Controlling 12VDC 5A relay from voltage signal?

[Micheal]

Hi,  I’m not an electronics engineer, but have some knowledge and keen to learn more.  I want to control a simple relay – 12VDC 5A – in response to a control feed which varies voltage according to state.  If control signal voltage is greater than 6 vdc the relay should energise, if the control signal voltage is less than 1.5 vdc, the relay should release.  Any circuits available would be appreciated.

[AJISH ALFRED]

Use schmitt trigger circuit, it can be easily made using 555.

 

Scmitt Trigger circuit using NE 555

http://www.allaboutcircuits.com/vol_6/chpt_8/2.html

 

Use a transistor at the output of 555 to drive the relay

 

[Ashutosh Bhatt]

you can use LM741 chip as comparator. and set its input voltage as you require. you can set the output high till input is more then 6 V and set output low when input is lower than 1.5 V. use this output to energize relay coil.

[Micheal]

Thank you Both.

 

I’ll have a play and report back.

[AJISH ALFRED]

You are welcome Micheal, waiting for your update.

[Author]

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