Author Topic: Pls Help Me in Creating Relay Driver For pic16f877 (Read 1257 times)

marcasjr™ · « **on:** February 25, 2008, 12:52:32 AM »

i need to drive a magnetic lock using relay.but pic16f877 cannot drive the relay.
my magnetic lock is 12v.
tnx for any replys

Philippine Electronics Forum · « **on:** February 25, 2008, 12:52:32 AM »

marcasjr™ · « **Reply #1 on:** February 25, 2008, 12:53:19 AM »

pls provide schemtics..
tnx..

Philippine Electronics Forum · « **Reply #1 on:** February 25, 2008, 12:53:19 AM »

Shey · « **Reply #2 on:** February 25, 2008, 01:11:09 AM »

Ganito lang yun. Yung base resistor from 4.7K to 10K ang value niya. Yung bypass capacitor siyempre 0.1 uF. Yung transistor bale general purpose transistor ok na yan..

Philippine Electronics Forum · « **Reply #2 on:** February 25, 2008, 01:11:09 AM »

toasted siopao · « **Reply #3 on:** February 25, 2008, 06:14:46 AM »

Do not forget to put that diode between the coils of your relay.

Philippine Electronics Forum · « **Reply #3 on:** February 25, 2008, 06:14:46 AM »

marcasjr™ · « **Reply #4 on:** February 25, 2008, 07:01:15 AM »

I will try it now
tnx.

Philippine Electronics Forum · « **Reply #4 on:** February 25, 2008, 07:01:15 AM »

zer0w1ng · « **Reply #5 on:** February 25, 2008, 02:31:45 PM »

I think the base capacitor is not needed. The diode in parallel to the relay coils are very IMPORTANT though.
If absent, the NPN transistor will be damaged due to reverse voltage generated by the coil after it is de-energized.

If you are using multiple relays in your circuit, you could use ULN2003 as relay drivers.
This is multiple darlington transistors in one 16 pin DIP package including the resistors and diode.
Easy interfacing for beginners

.

Philippine Electronics Forum · « **Reply #5 on:** February 25, 2008, 02:31:45 PM »

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