# DIY parking sensor

Updated on November 7, 2012

My garage is full of things, and almost every day I trip in my garage. I need all those things, and that is why I keep them. This is the main reason why I bump my car occasionally. While searching for some solution I was inspired about those parking sensors, which I think will help me avoid bumping my car, while parking it in the garage. Because of the fact that I prefer to solve my own problems, I made my own parking sensor and saved money, which I will use for some other purposes.

## The electronic circuit

The circuit is designed with only one purpose. It has to assist the driver while he is parking the vehicle in the garage or in a public parking space. It works by signalizing the driver (the LED 7 blinks) when the distance from the other object reaches 20 centimeters. The other two diodes (D7 and D6) start to blink when the distance reaches 10 centimeters. In case you do not notice the LED’s blinking, the last warning is when the vehicle reaches 6 centimeters from the other object. In this case LED’s 5, 6 and 7 blink.

All distances that I previously mentioned vary according the used diodes listed as D1 and D2, and of course the colour of the reflecting surface or object (the object that you are trying to avoud). Objects or surfaces that are black decrease the sensitivity. It is obvious that this application could be useful in cases you need to measure the level of any liquid.

The circuit IC1 is actually an oscillator which awakes LED’s with impuls frequencies of approximately 120 Hz and 300 mA peak current. D1 and D2 are placed towards the vehicle in the same line as the vehicle, separated from each other about 3 to 5 centimeters, and mounted on a board that is securely placed on the wall. The D2 diode gathers the infrared light produced by the D1 diode and was reflected by the vehicle. The signal is amplified thanks to IC2A, and the peak of the signal is detected with D4 and C4. The DC voltage which is proportional to the distance between the reflecting surface and the vehicle is delivered on the inputof the three voltage comparators. These comparators actually turn on and off LED’s. Turning on and off depends on the voltage of non inverting inputs, which actually is the resistor set of R7, R8, R9 and R 10, also called voltage splitter.

Here are the best parking sensors and theri prices. The one that I described will cost \$4.99.

## What parts you will need

Here is the list of the parts that you will need if you want to build this appliance, if you want to do it by yourself.

R1 = 10K 1/4W resistor
R2, R5, R6, R9 = 1K 1/4W resistors
R3 = 33R 1/4W resistor
R4, R11 = 1M 1/4W resistors
R7 = 4K7 1/4W resistor
R8 = 1K5 1/4W resistor
R10, R12, R13, R14 = 1K 1/4W resistos

C1, C4 = 1µF 63V electrolythic condensators
C2 = 47pF 63V ceramyc condensator
C3, C5 = 100µF 25V electrolythic condensator

D1 = Infra-red LED
D2 = Infra-red photo diode
D3, D4 = 1N4148 75V 150mA diode
D5, D6, D7 - LED

IC1 - NE555
IC2 - LM324
IC3 - 7812

## How would you rate the parking sensor?

5 out of 5 stars from 3 ratings of Parking sensor

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