Realay and diode connection

[udayp]

Sir.
I have 5 volt relay and my power supply is 9 volt, to protect relay from 9v can i use 5.2 volt zener diode across relay instead of IN4007 diode.
If yes means what should be the polarity of zener across relay coil.

 

[FvM]

To reduce the relay voltage, you have to connect zener diode (3V9) or simply a resistor in series with the relay coil. The free wheeling diode (1N4007) should be connected as usual.

A zener diode parallel to the coil would overload the diode as well as the driving switch and possibly damage both.

 

[udayp]

Thank you sir.