Nicad Battery Charger
Notes:
This simple charger uses a single transistor as a constant current source. The
voltage across the pair of 1N4148 diodes biases the base of the BD140 medium
power transistor. The base - emitter voltage of the transistor and the forward
voltage drop across the diodes are relatively stable. The charging current is
approximately 15mA or 45mA with the switch closed. This suits most 1.5V and 9V
rechargeable batteries. The transformer should have a secondary rating of 12V ac
at 0.5amp, the primary should be 220/240volts for Europe or 120volts ac for
North America.
WARNING: Take care with this circuit. Use a voltmeter to observe correct polarity. Nicads can explode if short circuited or connected with the wrong polarity.
Title: Nicad Battery Charger
electronic circuit
Source: www.electronics-lab.com
Published on: 2005-02-03
Reads: 1161
Print version: 
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