Solar Charger Circuit Project Using Transistors

A very simple solar charger circuit project can be designed using few external electronic parts . This simple solar charger circuit is capable of handling charge currents of up to 1A. Alternate component values are given in the figure for lower current applications.

Solar Charger Circuit Project Using Transistors circuit diagram :

The only adjustment is the voltage trip point when the current is shunted through the transistor and load resistor. This should be set with a fully charged battery. As the transistor and R3 have the entire panel’s output across them when the battery is fully charged, all of the current from the panel will be going through R3 and the Darlington transistor TIP112, so these must be well heat sunk. Adjust R1 for the trip point, usually 14.4 V – 15 V for a 12 V SLA or a 12 V Ni-Cd battery.

Source : http://www.ecircuitslab.com/2011/06/solar-charger-circuit-project-using.html

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How to Understand and Use High Voltage Transistors BUX 86 and BUX 87

The Bux 86 and BUX 87 are typically high voltage switching transistors with silicon epibase. They come in TO-126 package and are NPN types.

These devices are especially known for their outstanding short switching characteristics and for having a high dielectric strength.

The main applications using these devices can be found with TV circuits, electronic ballasts, converters, SMPS power suppliers etc.

The maximum tolerable electrical parameters for BUX 86 and BUX 87 may be understood with the following points:

Maximum collector to emitter voltage for BUX 86 is 400 volts and 450 Volts for BUX 87.

Maximum tolerable collector current for is 500 mA for both  the devices. 

Maximum tolerable instantaneous peak current across collector and emitter is 1 Amp for <2 ms for both the devices

Maximum tolerable constant base current is 200 mA for both the devices.

Maximum peak instantaneous base tolerable current is 300 mA for both the devices.

 Maximum power dissipation must not exceed 20 watts for both the devices

Typical Static characteristics @ 25 degree ambient temperature of BUX 86 and BUX 87 transistors are listed below:

Collector cut-off current is <0.1 mA

Typical forward current gain for both the devices is around 50

Collector to emitter saturation voltage is less than 1.5 V @ 100 mA collector current and 10 mA base current.

Base to emitter saturation voltage is less than 1 volts @ 200 mA collector current and 20 mA base current.

Maximum frequency handling capacity is 20 MHz for both the devices

Turn ON switching speed is 0.25 micro-second.

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