Schematics of delabs

This is a simple toy that has many applications. Any object that breaks a light beam will trigger a relay to on condition for a period of time.

Optical obstacle switch - del50006

Description - The 555 monostable has a 1 second period, If pin 2 gets low trigger pulses of a frequency more than 1 Hz, the output pin 3 will remain high, if the trigger pulses came in 10 second delays then output will go on and off, so also the relay and the electrical load on relay contacts. Like an integrator, it will not operate relay very fast. Even in a fridge stabilizer they put something like this else the compressor motor is damaged on frequent black-brown outs.

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The proximity switch can work for a wide range of power, from 8v to 18v DC, D3 protects reverse power supply connections, and U1 regulates the supply to +5v , -5v is derived from U2 555 oscillator which serves dual purpose.

Circuit Operation

Part of - InfraRed LED Flasher for Optical Switch

The infra red diode D2 detector gets the reflected light from LED and some ambient light, The forward voltage drop of D2 will vary with the amount of light falling on it. Ambient light causes a DC component and the pulsing light from D1 causes an AC component.

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This circuit is used to detect objects by reflected infrared light. It can be built into a cylindrical enclosure just like an inductive proximity switch.

Part of - InfraRed Detector for Proximity Switch

This is also useful as a level detector for colored liquids like oil. This has some immunity to ambient sunlight as it detects ac pulses.

Infrared Optical Proximity Switch

IC 555 is used as an astable oscillator and it flashes the Infra red LED D1 at a high speed, The object close to this LED reflects the light along with the ambient light which may also be sunlight.

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