Battery charger with LM317


Posted on Mar 25, 2013

An LM317 voltage regulator is configured as a constant-current source. It is used to supply the 50 mA charging current to S01-S06, an array of AA-cell battery holders. Each of the battery holders is wired in series with an LED and its associated shunt resistor. When the battery holder contains a battery, the LED glows during charging. Each battery holder/LED combination is paralleled by a 5.1-volt Zener diode. If the battery holder is empty, the Zener conducts the current around the holder.


Battery charger with LM317
Click here to download the full size of the above Circuit.

A timing circuit prevents overcharging. When power is applied to the circuit, timing is initiated by IC2, a CD4541 oscillator/programmable timer. The output of IC2 is fed to Ql. When that output is high, the transistor is on, and the charging circuit is completed. When the output is low, the transistor is off, and the path to ground is interrupted.




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

temperature stable oscillator
Square-wave-pulse-extractor
Engineering
Grid Dip Oscillator (GDO) Instrument
USB Battery Charger for AA NiMH and NiCd
led music level indicator light circuit
miconghs
100w power amplifier using STK404 integrated circuit
Door Ajar Alarm Circuit
Luxury Car Interior Light
Oscillator circuits
Voltage multipliers
Two-Zone Alarm



Top