We have a FINDER relay, with this scheme:

enter image description here

I want it to operate as a transistor, in the sense that a signal can control the connection of two other lines (i.e., the collector connects to the emitter only when there is 12V on the base).

According to the relay pinout, the collector should be clearly the pin labelled 11, and the emitter to 14 (given 11 connects to 12 by default, i.e. base=0V). Now, where should the base connect? And the power supply? Actually, the collector is the power supply itself, is there any problem if the line connects two pins?


closed as unclear what you're asking by Scott Seidman, brhans, Bence Kaulics, Daniel Grillo, Voltage Spike Aug 11 '16 at 17:43

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  • 5
    \$\begingroup\$ A relay is a complete different thing than a transistor. You cannot use a relay in place of a transistor, unless you only want to switch a load on or off. You should specify better what you mean exactly by "operate as a transistor", otherwise your question is utter nonsense. \$\endgroup\$ – Lorenzo Donati Aug 11 '16 at 0:24
  • \$\begingroup\$ Tried to include some clarification, but I believe my point is clear. May be you want the title more precise? \$\endgroup\$ – nightcod3r Aug 11 '16 at 0:30
  • \$\begingroup\$ although in some instances that analogy could be correct, I'd suggest dropping it since its been causing more confusion than anything else. Just state that you need 2 lines connected when some voltage is applied. Then we'll ask details such as how much current you have available, etc etc.. \$\endgroup\$ – Wesley Lee Aug 11 '16 at 0:35
  • 2
    \$\begingroup\$ @WesleyLee was spot-on. The "operate as a transistor" part is completely misleading and has nothing to do with your problem. You just want a relay to operate as a relay (i.e. as an electro-mechanical switch)! \$\endgroup\$ – Lorenzo Donati Aug 11 '16 at 0:50
  • \$\begingroup\$ What are you planning to use to switch this relay? A microcontroller? \$\endgroup\$ – johnny_boy Aug 11 '16 at 0:58

You are looking for the standard function of a relay. People are complaining about the transistor analogy because your transistor is already configured to act as a relay :)

Here is an example of a standard connection. SW1 might be a switch, a button, coming from some other transistor, from a PLC, etc...

enter image description here

If you want to hook your 12V power supply up to the "collector", change the circuit so that it looks like this:

enter image description here

Usually this would be done because you want to switch more current than SW1 could handle.

By the way, when referring to relays the standard pin names are:

  • A1: One side of the coil
  • A2: The other side of the coil. Often connected to ground.
  • COM: The pin that you are calling the "collector"
  • NC: "Normally Closed" - The pin that is connected to COM when the relay coil is not energized
  • NO: "Normally Open" - The pin that is connected to COM when the relay coil is energized

Like this:

enter image description here

  • \$\begingroup\$ A positive attitude is important when beginners arrive here to learn and solve their first problems. And that's something that you've showed. Now, everything is clear. \$\endgroup\$ – nightcod3r Aug 11 '16 at 8:35
  • \$\begingroup\$ @nightcod3r, glad to help :) \$\endgroup\$ – bitsmack Aug 11 '16 at 17:03

If you just want to completely switch on or off a load ...

A1 and A2 get the control signal (like gate of mosfet)

14 and 11 go between power and load (like source drain of mosfet)


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