Wiring Material: nicad

Showing posts with label nicad. Show all posts

Tuesday, August 26, 2014

Supper Deluxe Charge Rate Limiter for Small Capacity NiCad Batteries

Here is a deluxe version of the simple charge rate limiter, using the same idea but with the ability to charge two packs simultaneously from a single wall charger. For schema description and parts list, see the simple charger page. Since wall chargers provide about 55mA, you should not use this dual schema to charge batteries at rates greater than 27mA (for a total of 54mA).

Thursday, August 21, 2014

Simple Portable Nicad Battery Charger Wiring diagram Schematic

This is a Simple Portable Nicad Battery Charger Circuit Diagram. This Simple Portable Nicad Battery Charger Circuit Diagram was designed to charge NiCad battery packs in the range of 4.8 to 15.6 V from a convenient remote power source, such as an automobile batter.

Portable Nicad Battery Charger Circuit Diagram

When power is first applied to the schema, a small bias current supplied by Rl via winding Wl, starts to turn on the transistor TRl. This forces a voltage across W2 and the positive feedback given by the coupling of Wl and W201uses the transistor to turn hard on, applying the full supply across W2. The base drive voltage induced across Wl makes the junction between Rl and R2 become negative with respect to the 0-V supply, forward-biasing diode Dl to provide the necessary base current to hold TRl on.

With the transistor on, a magnetizing current builds up in W2, which eventually saturates the ferrite core of transformer Tl. This results in a sudden increase on the collector current flowing through TRl, causing its collector-emitter voltage to rise, and thus reducing the voltage across W2.

The current flowing in W2 forces the collector voltage of the TRl to swing positive until restricted by transformer output loading. Rc network R4 and C3limits the turn off transient TRl. R3 and C2 maintain the loop gain of the schema when diode Dl is not conducting.

Wednesday, August 20, 2014

Simple Nicad Battery Charger

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.

Simple Nicad Battery Charger Circuit diagram :

WARNING: Take care with this schema. Use a voltmeter to observe correct polarity. Nicads can explode if short schemaed or connected with the wrong polarity.