| Author | Views | Views Today | Rank | Comments |
| 94,488 | 117 |   |
81 |
| Author | Views | Views Today | Rank | Comments |
| 94,488 | 117 | |
81 |
|
This handy little circuit can tell the difference between darkness and light, making it very useful for switching on and off signs, porch lights or other things when it gets dark or light. |
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| NPN Photodetector? One could never tell from the outside whether it's NPN or PNP. Assume it's a typical relay, say 200 ohm coil. If you connect this circuit to a 9V battery, it will draw three times as much current as a 9V battery usually supplies. The battery will last only a few hours. The coil should have a 1N4002 rectifier across it, cathode to the positive end. | ||
| it's vrey useful for students | ||
| can any give me the schematic for controlling the dim and dipping of the headlamps of the vehicle when it detects the vehicle coming in the opposite direction to it.. so as to make the people see the roads properly during night | ||
| where can i get a device that can detect whether the street light is out during the day? my job is to locate streets lights that are out so i can report to the electric company for them to replace the lights. I dont want to have to go out at night and locate the lights that are out and during the day all lights are off so i can't tell. thanks | ||
| i wasn't able to get a phototransistor so i used an LDR and a 50K preset, works fine. the diode didn't make much difference,it's only for theory buffs. pcb is so easy to design.....duh! | ||
| Hello Im i beginner and am finding it very hard to translate this circuit onto a strip-board. Please can you provide a strip-board layout for me to follow. Many thanks, Jethro | ||
| Its a good and easy to make Circuit. Its so easy to make this circuit on bred board. I will recommend to all readers of this page to make this circuit. I hardly took 5 minutes for me to make it on bred board. "It really Works". | ||
| It doesn't work. I tried it.. it works if you use an LED instead of a relay. but in case of a relay there is a huge voltage drop at the emitter of the 2n2222 transistor and there isn't enough to energize the relay coil. | ||
| While the comment about the flyback diode is correct this circuit is in about every entry level electronics book. You don't need a PCB for this circuit as it is easy to layout on a perf board, but Dave Cutcher might have the board. He wrote the book Elelctronic Circuits for the Evil Genuis and used such a board for the projects in the book. | ||
| can any give me the schematic for controlling the dim and dipping of the headlamps of the vehicle when it detects the vehicle coming in the opposite direction to it.. so as to make the people see the roads properly during night.. | ||
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