How to make a Proximity Detector Circuit Using IC 555

In the following article we discus an easy IC 555 based proximity detector circuit.

An infrared proximity detector might be viewed as one of the crucial beneficial and commonly used circuits in electronic automation application range.

We can easily generally view it being utilized in automatic water dispensers, automatic hand dryer units along with precise variants could possibly be observed in the automatic doors of department stores.

Performing concept of the suggested proximity detector circuit applying IC 555

In the design a generation of speedy bursts of peak voltage pulses from the IC LM555 is carried out at a pretty lower frequency rate, that may be carried through the infrared LED as jets of IR beams.

These carried pulses are targeted toward the area which is certainly recommended to be supervised, and is reflected back when a subject or intruder is identified over a phototransistor diode situated advantageously for acquiring these included signals..

Once this occurs the experienced signals examine processing with a purpose to allow an connected relay mechanism and consequently an alarm device to get activated.

To examine the above application an object could be presented across the zone of the IR beams and the result could be inspected by monitoring the relay operation, such as by moving hand in the targeted area, within a distance of about 1 meter.

When the incorporated signals hit the phototransistor, it arises a potential difference across the 1M pot (adjustable) and activates the linked Darlington stage, which inturn trigger the right hand side 555 stage designed as a monostable circuit.

The relay gets triggered in accordance with this and stays ON dependent upon the monostable predetermined time delay set by the 1M as well as the 10uF capacitor.


simple proximity detector Circuit using IC 555


Parts List fro the suggested IC 555 based IR proximity detector circuit.

2 IC LM 555

2 IC sockets 8 pin

1 relay 12 V 5 pin

1 Infrared Phototransistor General Purpose

1 Infrared Diode General Purpose

3 BC547

2 capacitors. 10 uF / 50 V

1 1N4148 diode

1 red led 5mm

1 68 H

1 1K5

2 10K

1 100K

1 470 R H All 1/2 W

1 10k 1/4 w resistor to be hooked up concerning 1M preset center lead and the BC547 pair