How do I wire a transistor to a dpdt relay

Question

I have TQ2-L2-3v DPDT relay that is getting activated by an ESP8266-12e pin. The problem is the pin doesn’t always output enough current to activate the relay so I want to wire a transistor (2n2222) to it. My question is since the only relays I have thus far connected to the 2N2222 have been non latching with the positive and ground interchangeable The TQ2-L2-3v has a designated + and - so I am not sure which way to wire it up. I have made two schematics with the two different way I can think of the wiring. Can someone tell me which way is the correct A or B, or are these two incorrect and what is the correct wiring?

With D1 in the polarity you indicate, you're building a transistor blower-upper. You want the diode to be blocking when the transistor isn't conducting; it is there to conduct when the transistor turns _off_ and the coil needs a place for its current to go. — TimWescott, Jun 10 '22 at 03:31

score 1 · Accepted Answer · answered Jun 10 '22 at 00:14

1

L2 designates a two coil latching relay, so you would need another transistor and GPIO pin.

The + pin will go to Vcc (it will be more positive when the transistor is conducting), but I'm not sure of your diagram- it appears to be rotated 180° for the markings to be readable, assuming it's the top view.

For future reference, please link to the datasheet PDF in your question text.

answered Jun 10 '22 at 00:14

Spehro Pefhany

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So let’s say I had the same set up on the other side. If VCC goes to + then B would be the correct set up, right – user1114881 Jun 10 '22 at 00:32
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But the diode is backwards. – GodJihyo Jun 10 '22 at 00:52
So the 1n4148 needs to be turned around to go from - to + in B and it should work. – user1114881 Jun 10 '22 at 01:19
YES the diode is backwards, otherwise B is correct. – Spehro Pefhany Jun 10 '22 at 01:34
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Thank you very much – user1114881 Jun 10 '22 at 01:37

How do I wire a transistor to a dpdt relay

1 Answers1