Step Up

[Jbirk]

How do I create a circuit to step up the voltage to run an led?

Please give me some kind of a basic non filtered diagram that shows how to change DC to something that can be processed by a transformer.

I have taken two electronics cources and know that I will obviously need some kind of transformer or autotransformer. The problem is that a transformer will not work with direct current. I probably will need some kind of a transistor/capacitor circuit that chops or inverts the direct current so it can be processed by a transformer. Furthermore, the output of the transformer will probably be some form of a crude AC current that will be pulsating negative and positive; so, I will most likely need a capacitor, inductor, and zener diode to regulate the voltage.

I hope someone can give me a circuit diagram.

Thank you.

BTW, I want to run an led that is designed to run between 3.6 to 4 volts at 4.5 to 5 from a 3v power source that I plan to step up.

I do not mean to be too much trouble, but once I figure out how to build it, how am I going to make it small enought to fit in my flashlight?

Thanks

 

[Jonathan]

Search the electronics forum here, you will find many answers.

You are quite correct that these circuits require some sort of non-DC current flow; there are many variations, including using an oscillator to produce alternating current, followed by a transformer, to using a switching transistor to charge up capacitors, to switching current flow in inductors.

Here is my stab at a circuit; you will find others:
http://borealis.com/~winnie/LED_BOOST/index.htm

-Jon

 

[UK Owl]

Your invertor idea is far more complext than you need for the low power requirements of an LED. Try searching in google for MAX756 or MAX757 data sheets, either will do the job with minimal additional components.

i.e. an inductor (wind it yourself with a small piece of ferrite of a broken ferrite ring, and about 10 - 20 turns of enameled wire salvaged of an old relay)

a schotky diode (and ordinary diode may be used but efficiecy will be terrible)

a capacitor ( to store the charge)

if you use a MAX757 you will also need a couple of resistors (for programming the voltage).

If you wish to make a cheapo option using transistors rather than a MAXIM chip seach for 'dc boost circuit' on google.

All the best, happy moding, and good luck !