Circuit Project Description
The circuit was designed to produce an indicator to aid a car from parking especially in places without clear visibility.
1N1418 – a small-signal silicon epitaxial planar diode used for fast switching applications with a reverse voltage of 100 V and forward current of 150 mABC550 – an NPN general purpose transistor with low current and low voltage used for low noise stages in audio frequency equipmentCMOS 4093 – a quad 2-input NAND with Schmitt trigger inputs integrated circuit, generally characterized by small fluctuation in voltage supply, very high impedance, outputs that can sink and source, one output can drive up to 50 inputs, high speed gate propagation time, high frequency, and low power consumptionLight Emitting Diode (LED) – a semiconductor diode that is commonly a source of light when electric current pass through it Circuit Explanation
The operation of the circuits commences upon hitting the elastic material by the car’s bumper. This elastic material turns ON the switch S1 to provide an indicator to the driver. As the car softly touches and triggers the switch, the circuit becomes a closed loop enabling the 9 V battery with clip to provide power to the circuit. The transistor Q1 is turned ON at this stage, which would cause the LED D3 and D4 to light and blink. The two LED are positioned in a way that the driver would be notified as they begin to produce light or blink. They should be properly placed to where the driver can see them when they look at the rear view mirror or on their side mirror if parking backward. If the parking is made with the bumper faced front, the LED indicator should be visible enough.
This indication will last for 4 seconds after which the capacitor C1 will start charging. This will cause the pin 9 of IC1 to obtain high voltage and at the same time causes pin 10 to obtain low voltage. At this stage, transistor Q1 will turn OFF causing the LEDs to extinguish their light. Until the next triggering of the switch, the circuit will continue to be at this idle state. This will provide the battery a lot of time to conserve energy since the consumption of power is very minimal at this point of the circuit. To produce a continuous light indication for about 4 seconds, the diode D1 is represented by a 5 mm LED. The use of flash LED in place of diode D1 is not essential. However, the time that the LED will turn on can be varied by the changing of the capacitor C1 value whose value in the circuit is 4.7 uF at 25 V, for the 4 seconds delay time. Increasing the value of capacitance to 10 uF will produce a 10 second delay time.
Although the circuit is very simple, extra attention should be given to the setup of switch S1 as this will provide the right indication for LED operation. The switch and battery supply should be enclosed in a housing that will not be greatly affected by humidity and other forms of liquid. On top of the position of the circuit will lay the LEDs indicators connected via cable. The visibility of the LEDs to the drivers should be applied to any type of small class vehicles. The switch can be any type of single pole single throw (SPST) type of switch wherein it returns to its normally open (OFF) position upon the release of the button, like the standard doorbell switch. A plate is utilized to suitably reach the switch and at the end of this plate is where the elastic material is attached. This will not cause any damage to the car’s color during the physical contact.
D2=Led 5mm Red normal or Flash
D3=Led 5mm Red normal
C1=4.7uF 25V [for ~4sec delay time]
|C2=100nF 100V MKT
S1=sw normal open
9V battery with clip
Some car park indicators may be presented in different forms. It can be a resemblance of a real traffic light where there are 3 LED stages of indication depending on the distance of the car that is parking. Also, an alarm sound or buzzer can be added to the circuit to be more noticeable to the driver. Using this circuit could provide more benefits to drivers which are not much skilled like the beginners to avoid further damage to the vehicle.