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Simple Fatigue Testing Circuit

This small circuit is fun way to check if anyone is tired or not!

It make LED blink very fast.

We can change how fast it blink.

If anyone is not tired can see the light is still blinking even when it goes fast.

But if anyone tired the LED blink will look slow or maybe will not see at all

This happen because our brain does not keep up with fast blink.

If anyone sees fast blink then maybe thy are not so tired.

Circuit Working:

Parts List:

ComponentQuantity
Resistors
47k 1/4 watt1
100k 1/4 watt1
390Ω 1/4 watt1
Potentiometer 250k1
Capacitors
Ceramic 0.1µF1
Semiconductors
IC 5551
LED 5mm 20mA1
Battery 9V1

This tired checking circuit uses 555 IC working like astable multivibrator.

It checks how tired person is by seeing how good they see blinking light.

This circuit is easy to make as one LED blinks from 555 IC output.

We can change blink speed using P1 potentiometer.

Blink can go from 20 to 50 times in one second.

People see blink best when it flash around 30 to 40 times per second.

Formula:

This formula show how to find frequency for 555 IC working in astable mode with circuit above:

F = 1.44 / (R1 + 2R2) × C

where,

This formula think duty cycle is almost 50%.

That mean how long output stay ON compare to full cycle time.

How to Build:

To build a Simple Fatigue Testing Circuit one need to follow the below mentioned steps:

Connect the 555 IC:

Make astable setup:

Connect the LED:

Add potentiometer:

Give power to circuit:

Change the blink speed:

Optional: Add switch and box:

Test circuit:

Note:

Conclusion:

To conclude this Simple Fatigue Testing Circuit use blinking light from oscillator usually 555 IC.

It make LED blink at different speeds.

By checking when person stop seeing the blink we can guess how tired they are.

If they do not see fast blink maybe they are more tired.

This way circuit gives simple and useful way to test tiredness using eyes and fast light.

References:

 Fatigue test equipments and (b) circuit diagram

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