USB li-ion charger

Here is a simple li-ion charging from the site circuitsdiy.com it does not contain specialized circuits charging and assembled on a regular LM258N. The scheme can be used for efficient charging one cell Li-ion batteries such as in a mobile phone.

Features:

Charging through a very common mini-USB connector.
Status shows charging indication LEDs.
A simple scheme which basis are an operational amplifier.
Charges even fully discharged battery.
The maximum charging current 500mA (limited USB power), depending on the battery.

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Electronic candle on AVR

This story begins on the eve of the last new year. Sister asked me to make a fairylight for their New Year costume of firefly. Light should look fabulous and unusual. At the attic long was lying an old lamp which had been fitted with paraffin candle. Variant with a real candle was rejected immediately because of its flammability and in head immediately appeared idea to show engineering ingenuity.

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Simple step-up DC – DC converter on a single transistor

Simple step-up DC – DC converter on a single transistor

This converter works almost with any elements. I assembled with his pile of rubbish over, literally 5-10 minutes. Although current output goes low (about 30mA), but with a small strapping power will be enough for LED or microcontroller .

Its main advantage is that it works from 1.2V battery. But be careful if you give it more than 3.0V, then the circuit may fail.

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