Showing posts with label light. Show all posts
Showing posts with label light. Show all posts
Friday, April 12, 2013
Low Cost Garage Stop Light
A novel use of solar cells makes positioning your car in the garage rather easier than old tyres, a mirror, or a chalk mark.The six solar cells in figure 1 serve as power supply and as proximity sensor. They are commercially available at relative low cost. The voltage developed across potentiometer Pi is mainly dependent on the intensity of the light falling onto the cells. The circuit is only actuated when the main beam of one of the cars headlights shines direct onto the cells from a distance of about 200 mm (8 inches). The distance can be varied somewhat with P,
Low Cost Garage Stop Light Circuit Diagram :
Under those conditions, the voltage developed across C1 is about 3 V, which is sufficient to trigger relaxation oscillator Ni. The BC547B is then switched on via buffer N2 so that D3 begins to lfash. Diodes Di and D2 provide an additional in-crease in the threshold of the circuit. The total voltage drop of 1.2 V across them ensures that the potential at pin I of the 4093 is always 1.2 V below the voltage developed by the solar cells. As the trip level of Ni lies at about 50 per cent of the supply voltage, the oscillator will only start when the supply voltage is higher than 2.4 V.
The circuit, including the solar cells, is best constructed on a small veroboard as shown in figure 3, and then fitted in a translucent or transparent manmade fibre case. The case is fitted onto the garage wall in a position where one of the cars headlights shines direct onto it. The LED is fitted onto the same wall, but a little higher so that it is in easy view of the driver of the car. When you drive into the garage, you must, of course, remember to switch on the main beam of your headlights!
Source: http://www.ecircuitslab.com/2012/09/low-cost-garage-stop-light.html
Thursday, April 11, 2013
Light Activated Switch Circuit Using LM311
This is a design circuit diagram of a light activated switch. This circuit is based on National Semiconductors comparator IC LM 311 and a LDR for operation. This is the figure of the circuit.
The circuit is based on a voltage comparator circuit wired around IC 1. The non-inverting in put of IC1 is given with a reference voltage of 6V using resistors R3 and R4. The input to the inverting input will be the voltage across the LDR that is light dependent. At darkness the resistance of the LDR will be high and so do the voltage across it. At this condition the voltage at the inverting input will be higher than the reference at non inverting pin and the out put of the comparator will be low(~o V). Adjust POT R1 to set the desired light intensity for switching the relay. For this illuminate the LDR with the desire intensity light.
The relay will be either on or off. Adjust POT R1 slowly so that the state of the relay changes. That’s it. Now the circuit is set for the given intensity of light. When the LDR is illuminated, its resistance drops and so do the voltage across it. Now the voltage at inverting input will be lower than that at non inverting input and the out put of the comparator goes high (~12 V). This makes transistor Q1 on and it drives the relay. As a result we get a relay switching according to the intensity of the light falling on the LDR.
You can use either a 12 V battery or a well regulated & filtered 12V DC mains operated power supply. The pin out of LM311 is also given together with the circuit diagram. The pin 5&6 (Balance & Balance/Strobe) of IC LM311 are shorted to minimize the chance of oscillations.
The circuit is based on a voltage comparator circuit wired around IC 1. The non-inverting in put of IC1 is given with a reference voltage of 6V using resistors R3 and R4. The input to the inverting input will be the voltage across the LDR that is light dependent. At darkness the resistance of the LDR will be high and so do the voltage across it. At this condition the voltage at the inverting input will be higher than the reference at non inverting pin and the out put of the comparator will be low(~o V). Adjust POT R1 to set the desired light intensity for switching the relay. For this illuminate the LDR with the desire intensity light.
The relay will be either on or off. Adjust POT R1 slowly so that the state of the relay changes. That’s it. Now the circuit is set for the given intensity of light. When the LDR is illuminated, its resistance drops and so do the voltage across it. Now the voltage at inverting input will be lower than that at non inverting input and the out put of the comparator goes high (~12 V). This makes transistor Q1 on and it drives the relay. As a result we get a relay switching according to the intensity of the light falling on the LDR.
You can use either a 12 V battery or a well regulated & filtered 12V DC mains operated power supply. The pin out of LM311 is also given together with the circuit diagram. The pin 5&6 (Balance & Balance/Strobe) of IC LM311 are shorted to minimize the chance of oscillations.
Wednesday, April 10, 2013
Efficient Automatic White LED Emergency Light Circuit
Description:
Referring the figure, we see that the circuit is actually very easy to understand, let’s evaluate it with the following points:
The transformer, bridge and the capacitor forms a standard Power supply for the circuit. The circuit is basically made up of a single PNP transistor, which is used as a switch here.
We know that PNP devices are referenced to positive potentials and it acts like ground to them. So connecting a positive supply to the base of a PNP device would mean grounding of its base. Here, as long as mains power is ON, the positive from the supply reaches the base of the transistor, keeping it switched off. Therefore the voltage from the battery is not able to reach the LED bank, keeping it switched off.
In the meantime the battery is charged by the power supply voltage and it’s charged through the system of trickle charging.
However, as soon as the mains power disrupts, the positive at the base of the transistor disappears and it gets forward biased through the 10K resistor.
The transistor switches ON, instantly illuminating the LEDs.
Initially all the diodes are included in the voltage path, and are gradually bypassed one by one as the LED gets dimmer.
Parts List
R1 = 10K,
C1 = 100uF/25V,
D1, D2 = 1N4007,
D3---D6 = 1N5408,
T1 = BD140
T1 = BD140
Tr1 = 0-9V, 500mA,
LEDs = white, hi-efficiency, 5mm,
S1 = switch with three changeover contacts.
Friday, April 5, 2013
Lighting Diagram Ceiling Light Images
Wiring Diagram Light Switch Wiring Diagram Light Switch 64038.
Wiring Diagram Light Switch Wiring Diagram Light Switch 34038.
How To Wire A Switch Light Then Switch At End Of Circuit.
Lighting Diagram Ceiling Light Images.
Line Diagram Of A One Way Lighting Circuit Using In Line Method Fig 1.
Power At Light 4 Way Switch Wiring Diagram.
Way Switch Wiring Diagram Variation 3 Electrical Online.
How To Wire A Switch Light Then Switch And Outlet.
Running Light Relay Is Connected To Ecu And Gauge Fuse 10a Parking.
Light Wiring Diagram Switch.
Car Boot Light Warning
On many cars, the boot light will not go out until the lid is properly closed. It is all too easy when unloading the car, to leave the lid ajar. If you are unlucky and the car remains unused for some time, the next time you try to start it, the lamp will have drained the battery and you will no doubt utter a few appropriate words. The circuit described here will give a warning of just such a situation.
A mercury tilt switch is mounted in the boot so that as the lid is closed, its contacts close before the lid is completely shut. The supply for the circuit comes from the switched 12 V to the boot lamp and through the mercury switch. When the lid is properly closed, the boot lamp will go out and the supply to the circuit will go to zero. If however the lid is left ajar, the lamp will be on and the mercury switch will close the circuit.
Car Boot Light Warning Circuit diagram :
After 5 seconds, the alarm will start to sound, and unless the lid is shut, it will continue for 1 minute to remind you to close the boot properly. The 1-minute operating period will ensure that the alarm does not sound continuously if you are, for example, transporting bulky items and the boot will not fully close. The circuit consists of a dual CMOS timer type 7556 (the bipolar 556 version is unsuitable for this application). When power is applied to the circuit (i.e. the boot lid is ajar) tantalum capacitors C1 and C2 will ensure that the outputs of the timers are high. After approximately 5 seconds, when the voltage across C2 rises to 2/3 of the supply voltage, timer IC1b will be triggered and its output will go low thereby causing the alarm to sound.
Meanwhile the voltage across C1 is rising much more slowly and after approximately 1 minute, it will have reached 2/3 of the supply voltage. IC1a will now trigger and this will reset IC1b. The alarm will be turned off. IC1a will remain in this state until the boot lid is either closed or opened wider at which point C1 and C2 will be discharged through R6 and the circuit will be ready to start again. To calculate the period of the timers use the formula: t = 1.1RC Please note that the capacitor type used in the circuit should be tantalum or electrolytic with a solid electrolyte. The buzzer must be a type suitable for use at D.C. (i.e. one with a built in driver).
Source : www.ecircuitslab.com/2011/.../car-boot-lamp-warning-icm7556.html
Thursday, April 4, 2013
Light sensor component
Electronic components are included in the category of light sensors are as follows:
ReadMore....
- LDR
- Photo Transistor
- Photo Diode
- Infrared Receiver
The function of the electronic component is to detect the intensity of light received by the component. The light sensor is often used in electronic equipment such as on television, light a light switch, light intensity measuring instrument.
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