Professor Slatton's Dark Electrons

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"You can't depend on your eyes if your imagination is out of focus" ~ Mark Twain

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Ralph Slatton has the BFA and MA degrees from Arkansas State University and the MFA from the University of Iowa.

Before pursuing an art degree Ralph Slatton had strong interests in science and math. He completed two years as a chemistry major at Arkansas State Univeristy. He also completed several years toward an Electrical Engineering degree at the University of Arkansas. He served as a radio team chief in the Army Air Defense in Grafenwohr, Germany, providing support for Hawk missle systems.

 


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Project:555 Timer Circuits

This is one of my favorite electronic projects constructed in my home lab when I was a kid.

555 timer circuit

Using the 555 as a Sequential Timer

Objectives:
This is one of my favorite projects, which I used in lots of art projects.  It uses the 555 as a timer switch that could also be used to trigger a series of events, powered by relays.
Schematic Diagram of Circuit
First refer to the schematic diagram given in Experiment 1. If you have not already performed Experiment 1, do so now before attempt­ing this experiment.

Step 1
The diagram shown will provide the basic wiring for your project. It will also list the parts used. Most of these parts can be purchased at Radio Shack.  In recent years, Radio Shack is getting away from kit building, so you may have to order your supplies online from a electronic parts catalog.

circuit diagram of 555 timer

You will note that 555 timers are used as mono-stable vibrators. the first timer will relay its pulse through a .0l mfd capacitor and 10 k resistor, triggering the second timer, and so on.

Step 2
When you connect power to your circuit, the LEDs should be unlit. If not, it may take a few seconds for them to reset to the off state.

Step 3
When both leds are off, quickly press and release the pulser. The first LED should light for 3 secs. and go out, then triggering the next circuit, thus lighting the second LED, etc. The .01mpf cap and the resistor value control the timing of the sequence.
 
Conclusion:
We are able to cascade a number of events and time each on with our sequencer circuit.  To drive larger amperages, you can substitute the led for a coiled relay. Make sure the relay can be triggered with a low power input, otherwise the current drain on the circuit would be excessive and would not trigger the relay.  I used this circuit to trigger motors, lights, and even other circuits. The application could also work with burlar alarms and rc-controlled devices.

Wave forms of the 555 timer

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