Hi, this is Wayne again with a topic “The Useless Candle”.
You’Ve probably seen the useless machine, the device whose only function is to turn itself off just for fun. I decided to apply this concept to something else, so this week, i’m going to show you how to make a useless candle. Whenever you light it, it will automatically blow itself out. This is done with a simple light sensor and a small air pump. When the sensor detects the increased light from the candle being lit, it turns on the air pump, which blows out the candle. The control circuit for this project is built around a 555 timer ic. When light shines on the photoresistor, the voltage at pin 2 drops below the trigger threshold. This sets the output at pin 3 high, which activates a power transistor and turns on a relay after a short delay. The system resets itself and the output is set low. Again. The two capacitors and fixed resistors control the delay when turning on and off the sensitivity of the sensor is set by adjusting the variable resistor. First, i prototype the system on breadboards, then, once everything is working properly, you’re ready to solder them together. I assembled the control circuit onto one board and i soldered the relay and its suppression diode onto a separate board to connect the air pump to the relay. You can separate and cut one of the wires of the power cord and connect the two ends to the switch terminals on the relay or, if you’d rather not cut the power cord itself, you can use a cheap extension cord when you’re done assembling the circuits mount Them inside a pair of insulated project enclosures, now we need to set up the candle with the light sensor and the air hose to do this. I got a small wooden candle stand with a back plate just above the top of the candle.
I drilled one hole for the air hose and two smaller holes for the leads of the photoresistor to help them not stick out as much. I used a brown marker to color in the edges to match the wood. Then i connected the photoresistor to the control circuit and the air hose to the pump and your useless candle is complete. Now, whenever you light the candle, it will automatically blow itself out it’s a lot of fun.
So why not make one for yourself thanks for watching and check back next week for more diy hacks and how to’s you .