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Topic: Virtual switch (Read 2 times) previous topic - next topic

CrossRoads

You didn't purchase the relay in #9, you purchased one that has lower coil resistance, which requires more current flow.
Thus you need an NPN transister which can control that larger current flow without overheating and burning up.
When a smaller amount of current is supplied to the base of the transister, a much larger amount of current is allowed to flow from the collecter to the emitter.
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

Carnyworld

C program run. C program crash. C programmer quit.

CrossRoads

The one that I linked to back in Reply #2 because it only  needs 31ma to turn it on, which the Arduino can handle.

I don't think any of these will work without a transistor as they all need too much current.
http://www.allelectronics.com/make-a-store/category/500200/Relays/DIP/1.html
Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

CrossRoads

Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

mrmeval

Even with the lower current relay you still need the diode or the reverse EMF can fry the arduino
If it was designed by man it can be repaired by man.

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