Basic Electronic Building Blocks

Slow LED Blinker

The period T in seconds is given by

T = 0.7 x (R1 + [2 x R2]) x C1

In general you want to keep R1 much smaller than R2, as indicated.

There is much information about the 555 timer on the Internet. Some of my favorites are:

555 Monostable Multivibrator experiment at All About Circuits
555 Precision IC Tutorial at the tronixstuff website

FET Transistor as a switch to control a motor

This circuit will work with any logic level N-channel MOSFET, such as the RFP12N10L. The datasheet for this transistor is here.

  1. Vdd can be any supply voltage 5V and above up to the maximum the transistor can handle. In the case of the RFP12N10L, this is 100V
  2. With the switch open, the 10K pulldown resistor makes sure the transistor is turned off and the motor should be off.
  3. Closing the switch will turn the transistor on and hence the motor on.
  4. Once you have confirmed the correct operation, you can replace the switch with any 5V signal, such as the slow blinker above, or an Arduino digital output.


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