Hello. There is winter outside and it is time regular outage electricity in the house. And i need a flashlight that will shine while electricity is off, it must have a stable hull, and it’s led must have wide angle of light. This idea left in my mind but later were forgotten. But one day i found next link http://we.easyelectronics.ru/Signaller/fonarik.html. Hull of flashlight totally satisfied my wishes. The article was posted that it is Soviet military flashlight, served to determine friendly fighters in the night attack. It was the second big plus, because everything that was made in the Soviet Union can serve couple hundred years , and that was made for the military can serve couple hundred years with a couple of nuclear wars. The next day I spent searching a similar a flashlight at a national auction Aukro found the best option according to the degree of preservation and price. Order and got.
I found simple and cheap “Latching Momentary Switch” circuit
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.
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.
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.