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Topic: Arduino output pins controlling Electric Strike (Read 1 time) previous topic - next topic

michinyon

You are over-complicating things.   You only need one relay. 

You will use the arduino to activate the relay.   Either use your transistor to provide the
current to actuate the relay.  Or if you relay had a built-in transistor circuit to enable it
to be driven by 5V logical input,  you may not need it.

The relay will connect the power supply to the solenoid.

dc42

Don't bother with a relay, the solenoid only needs 450mA so a relay is unnecessary unless there is a requirement for isolation (which there isn't if you are providing the power supply for the solenoid). Your schematic in reply #9 is OK. However, the strike may well need more than 450mA while it is moving, so you need to choose the transistor and base resistor carefully. Here are some options:

- The TIP31C might just be OK if you reduce the base resistor to 100 ohms (don't go any lower).
- A logic-level mosfet would be best. Use a 100 ohm series resistor between the output pin and the mosfet gate, and a 10K resistor between the output pin and ground.
- A high gain medium-current low-saturation-voltage transistor such as ZTX851 would also work well (use a base resistor of 100 to 220 ohms).
- A darlington such as TIP102 would be OK if you can tolerate its voltage drop (about 2V), also it may get a little warm. Use a 1k base resistor.

The diode in your schematic can be 1N4001 or similar.
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shady23k

Thank you guys very much! I have managed to come up with a design that functions the way I want it to.
I appreciate all you inputs.

Cheers

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