Car Parking Sensor circuit Using Infra Red LED

This circuit can be used for an assist in parking the car near the garage wall backing up Pls. LED D7 illuminates Pls bumper-wall distance is about 20 cm., D7 + D6 illuminate at about 10 cm. and D7 + D6 + D5 at about 6 cm. In this manner you are alerted Pls approaching too close to the wall.

Car Parking Sensor circuit

All distances mentioned before can vary, depending on infra-red transmitting and receiving LEDs used and are mostly affected by the color of the reflecting surface. Black surfaces lower greatly the device sensitivity. Obviously, you can use this circuit in other applications like liquids level detection, proximity devices etc.

Note:

• The infra-red Photo Diode D2, should be of the type incorporating an optical sunlight filter: these components appear in black plastic cases. Some of them resemble TO92 transistors: in this case, please note that the sensitive surface is the curved, not the flat one.
• Avoid sun or artificial light hitting directly D1 & D2.
• If your car has black bumpers, you can line-up the infra-red diodes with the (mostly white) license or number plate.
• It is wiser to place all the circuitry near the infra-red LEDs in a small box. The 3 signaling LEDs can be placed far from the main box at an height making them well visible by the car driver.
• The best setup is obtained bringing D2 nearer to D1 (without a reflecting object) until D5 illuminates; then moving it a bit until D5 is clearly off. Usually D1-D2 optimum distance lies in the range 1.5-3 cm.

List Component of Car Parking Sensor circuit:

R1 : 10K
R2,R5,R6,R9 : 1K
R3 : 33R
R4,R11 : 1M
R7 : 4K7
R8 : 1K5
R10,R12-R14 : 1K
C1,C4 : 1µF/63V
C2 : 47pF
C3,C5 : 100µF
D1 : Infra-red LED
D2 : Infra-red Photo Diode (see Notes)
D3,D4 : 1N4148
D5-7 : LEDs (Any color and size)
IC1 : NE555
IC2 : LM324
IC3 : LM7812 

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Infra red Level Detector

This schema is useful in liquids level or proximity detection. It operates detecting the distance from the target by reflection of an infra-red beam. It can safely detect the level of a liquid in a tank without any contact with the liquid itself. The devices range can be set from a couple of cm. to about 50 cm. by means of a trimmer.Range can vary, depending on infra-red transmitting and receiving LEDs used and is mostly affected by the color of the reflecting surface. Black surfaces lower greatly the devices sensitivity.








Parts:

R1_____________10K 1/4W Resistor
R2,R5,R6,R9_____1K 1/4W Resistors
R3_____________33R 1/4W Resistor
R4,R8___________1M 1/4W Resistors
R7_____________10K Trimmer Cermet
R10____________22K 1/4W Resistor


C1,C4___________1µF 63V Electrolytic or Polyester Capacitors
C2_____________47pF 63V Ceramic Capacitor
C3,C5,C6______100µF 25V Electrolytic Capacitors

D1_____________Infra-red LED
D2_____________Infra-red Photo Diode (see Notes)
D3,D4________1N4148 75V 150mA Diode
D5______________LED (Any color and size)
D6,D7________1N4002 100V 1A Diodes

Q1____________BC327 45V 800mA PNP Transistor

IC1_____________555 Timer IC
IC2___________LM358 Low Power Dual Op-amp
IC3____________7812 12V 1A Positive voltage regulator IC

RL1____________Relay with SPDT 2A @ 220V switch
Coil Voltage 12V. Coil resistance 200-300 Ohm

J1_____________Two ways output socket





IC1 forms an oscillator driving the infra-red LED by means of 0.8mSec. pulses at 120Hz frequency and about 300mA peak current. D1 & D2 are placed facing the target on the same line, a couple of centimeters apart, on a short breadboard strip. D2 picks-up the infra-red beam generated by D1 and reflected by the surface placed in front of it. The signal is amplified by IC2A and peak detected by D4 & C4. Diode D3, with R5 & R6, compensates for the forward diode drop of D4. A DC voltage proportional to the distance of the reflecting object and D1 & D2 feeds the inverting input of the voltage comparator IC2B. This comparator switches on and off the LED and the optional relay via Q1, comparing its input voltage to the reference voltage at its non-inverting input set by the Trimmer R7.


Notes:

* Power supply must be regulated (hence the use of IC3) for precise reference voltage. The schema can be fed by a commercial wall plug-in adapter, having a DC output voltage in the range 12-24V.
* Current drawing: LED off 40mA; LED and Relay on 70mA @ 12V DC supply.
* R10, C6, Q1, D6, D7, RL1 and J1 can be omitted if relay operation is not required.
* The infra-red Photo Diode D2, should be of the type incorporating an optical sunlight filter: these components appear in black plastic cases. Some of them resemble TO92 transistors: in this case, please note that the sensitive surface is the curved, not the flat one.
* Avoid sun or artificial light hitting directly D1 & D2.
* Usually D1-D2 optimum distance lies in the range 1.5-3 cm.

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