Flasing led

408

05:04:12

This is a novel flasher circuit using a single driver transistor that takes its flash- rate from a flashing LED. Theflasher in the photo is 3mm. An ordinary LED will not work. The high-bright white LED can be adjusted by altering the 1k resistor across the 100u electrolytic to 4k7 or 10k. The 1k resistor discharges the 100u so that when the transistor turns on, the charging current into the 100u illuminates the white LED.If a 10k discharge resistor is used, the 100u is not fully discharged and the LED does not flash as bright. All the parts in the photo are in the same places as in the circuit diagram to make it easy to see how the parts are connected.

published 11 years ago

rbrtkurtz

11 years ago

http://www.talkingelectronics.com/projects/200TrCcts/200TrCcts.html About 1/4 down the page. You need a flashing LED to make this work. We don't have them in EC, so you'll have to also build the oscillator that's inside the flashing LED that makes it flash.

Sine_eyed

11 years ago

Also, bright whites can vary quite a bit in their power requirements- so if you don't have/can't get the data for the LED you plan to use, I strongly suggest breadboard testing it before putting it into any circuit! I have some bright whites that look just like normal 5mm's, and they are PLENTY bright at only 8mA! And if I try to push anymore than 12mA thru, they'll pop for sure. So test them- and start with low voltage, and high resistance..

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