9 Volt Battery Chargers
Collection of batteries that "Don't Work"
Over just a few months, a pile of 9V batteries accumulated. Nothing was known about their status, except "They Don't Work" and that "This is getting expensive".
Some were new, some were old. There were Ni-Cad, NiMH, and rechargeable Akaline.
The LED on the device's charger said the batteries were charged, but reality said different.
I decided to learn to do by doing and ended up building 5 different battery chargers.
Ver 1.0 uses a resistor to limit current.
Ver 2.0 uses a constant current source to limit current.
Ver 3.0 improves on Ver 2.0. (Recommended)
Ver 4.0 uses an op amp and rheostat to provide 0- 16mA of constant current.
Ver 5.0 adds a transistor to Ver 4.0 to increase the current range to 0 - 160mA
Simple 1 Resistor Battery Charger
Constant Current Battery Charger from 2 LED's and a NPN Transistor
9V Battery Charger from 2 NPN Transistors
Adjustable Charge Rate Battery Charger from Op Amp
0 - 160 mA Adjustable Charge Rate Battery Charger
741C Cheat Sheet
Sparks and Flames
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