Run LED strings on USB chargers and power banks.

This is a very simple project to make an adaptor that lets you run parallel strings of LEDs from USB power supplies and power banks.  The types of string it can run are the parallel wired strings often found with solar powered strings or the battery powered strings.  If you use the newer "effect" strings where alternate LEDs are wired in inverse parallel then only half will light depending on which way you plug it in.
The circuit is designed to run the LEDs at a nice low level for efficiency and to maximise the lifespan of the LEDs.  This also allows even a basic USB power bank to run a set for a very long time.  Note that the cheaper power banks do not have proper low battery cut-off, so if the LEDs suddenly go dim then that's the time to unplug them and recharge the power bank.  With better quality power banks the LEDs will cut off suddenly when the battery is too low.

There's scope to change the resistor values for higher or lower output with corresponding shorter or longer battery life.  Note the need to avoid exceeding the power ratings of the resistors and the possibility of a short circuit overloading the resistors.

The resistors used in this project were two very common quarter watt 22 ohm resistors.

If you enjoy these videos you can help support the channel with a dollar for coffee, cookies and LED strings for modification at:-
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