Tagged Questions

3
votes
1answer
109 views

Safely extract power from USB

I am upgrading the lighting in a model with simple circuit which has 17 LEDs (approximately) plus one or two 555 timers. Presently, everything is powered by 3 AAA batteries. It drains between 150 and ...
1
vote
3answers
186 views

How to build simple 12v .5a regulator

I'm building a solar powered light. The idea of this light is that its output is proportional to the brightness of the sun. At night, no light. During daylight, full light. So it's basically as simple ...
0
votes
1answer
201 views

Building a new dynamo bike light

So here is the deal, for the 2nd time in less than a year, my halogen bike light on the front has popped due to cold. This is rather bothersome and I can't find any nice inexpensive LED alternatives ...
3
votes
2answers
394 views

Efficient constant-current regulator for 700ma LEDs

I'm building a lamp with twelve 3x700ma RGB LEDs in it, that need to be individually PWM controlled (100-200Hz), so they can display different colours from each LED. To do this then, I think I need a ...
8
votes
1answer
590 views

How can I calculate a Joule Thief

A Joule Thief is a simple step-up converter with which you can drive a 3.6V LED with a 1.5V battery even if it is spending the last drops of its life. It merely consists of a transistor, a transformer ...
5
votes
3answers
179 views

Dropping voltage for red channel on RGB LED

I'm looking at a Multicomp OSW-8349 RGB LED, which has a Vf of 3V min / 4V max for the green and blue channels, and a Vf of 1.8V min to 2.8V max for the red channel, at 350mA. I'm planning on ...
0
votes
1answer
169 views

LED setup with 110 standard outlet [closed]

I am attempting to grow an indoor garden. I would like to purchase LEDs to help grow my plants. Can you help me understand everything I need to power my LEDs (and not catch anything on fire). From my ...
2
votes
2answers
563 views

How to run LED lights off wild DC from bike powered generator

I teach 6th grade physical science. My electronics knowledge is limited. I have a bike powered generator from windstream power, and I have it hooked up to a board with light sockets so students can ...
4
votes
1answer
2k views

Voltage regulator for linear constant-current (1.5A) LED driver?

I am considering building my own driver for a ~1.5A LED to power a microscope for my research. For this application, efficiency isn't critical, but because exposure times to the camera can be short ...
-1
votes
3answers
1k views

Zener Diode for Minimum Voltage Regulator

I forgot the name of it, but I remember one post where it said that you can use a zener diode as a "minimum voltage regulator". I don't think I used the right term for it, but here's what I'm doing. ...
3
votes
7answers
821 views

how to drive a 1.35V led with a 1.4V AA battery

I would like to mount a TSAL6400 led on a single AA size battery box, with a simple ON/OFF switch. My problem is that the LED needs exactly 1.35V to function at its rated brightness. At this voltage ...