MAKE: ELECTRONICS – CHP 2 EXERCISE 8

Exercise eight, “A Relay Oscillator”. This exercise is a slightly revised version of exercise seven in which the direct connection was between the push button and the coil.  In exercise eight, the voltage arrives at the coil as a result of traveling through the contacts of the relay.  ex_8Therefore, when the push button is depressed, the contacts of the relay feed the voltage to both the coil and the leftmost LED.

The idea here is that when the coil is energized, it opens up the contacts of the relay.  This causes an interruption of power being sent to the coil ex_8_1allowing the relay to relax the state of the contacts – closing them.  The cycle repeats by sending another pulse of voltage to the coil that in turns opens the relay contacts again.

A capacitor is introduced to provide assistance in slowing down the oscillation process and assist in the visual observation of the cycling process – LED flicker.

ex_8_3This chapter provided some decent background information on capacitor basics  in addition to learning how to breadboard a circuit. Speaking of which, initially the exercise called for building the circuit without a breadboard. A beginner will definitely begin to appreciate the idea of the bread board after attempting to build this circuit without one.

Required Components:

– AC Adapter or Power Supply, wire, wire cutters and strippers
– DPDT relay
– LEDs
– Push button, SPST
– Alligator Clips
– Resistors 680 ohm
– Capacitor (electrolytic) 1000uf

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