Simple Inverter with Two Transistors

The series below is a simple inverter circuit that will change the voltage of 12v dc to 220v ac, with use drive transistor 32 as its tip.  Inverter circuit is very simple and easy to assemble and is perfect for just starting to learn to assemble electronic circuits, you can use the transformer 2A to produce about 20 watts output. Do not forget to install coolers in its transistors. good luck.

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12v battery charger using transistors circuit

A very simple 12v battery charger circuit can be designed using a TIP3055 power transistor to limit the current to the battery by turning off when the battery voltage reaches approx 14v or if the current rises above 2 amp.

This battery charger electronic circuit is very simple and require few external electronic parts . Signal to turn off the TIP3055 transistor comes from two other transistors , the BC557 and BC 547. Firstly, the circuit turns on fully via the BD139 and TIP3055. The BC557 and BC 547 do not come into operation at the moment.
As the battery voltage rises, the voltage divider made up of the 1k8 and 39k creates a 0.65v between base and emitter of the BC557 and it starts to turn on at approx 14v.
The input voltage required by this charger electronic circuit project must be around 15 volts DC.

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Transformer Voltage Booster Circuit DC DC Step Up Switching Regulator Using Transistors

A DC-to-DC step-up converter is traditionally implemented using transformer, working by converting the DC voltage to AC Voltage, step-up it using transformer, then rectify and filter the transformer’s output to get a higher DC voltage. Using a switching method, we can step-up a voltage without a transformer. We just need an inductor which is driven by a switching transistor to boost the voltage. This is the figure of the circuit.


The most interesting this is that circuits use a discrete component: no integrated chip is required, only few transistors with few passive components. Because the switching topology is a boost converter, this circuit cannot be operated as step-down regulator, so the output will always be higher than the input. The voltage output is depend on the load because the feedback mechanism, through the zener diode, will maintain the output at about 14 volt, regardless the voltage input variation and load current variation. The current from the voltage divider will flow through the zener diode if the output goes higher than the nominal value, and this condition will stop the oscillator built around the 2N3904 transistors. Stopping the oscillator will drop the output voltage and thus maintain the required voltage level at the output. This transistor (Q1, Q2, and Q3) form a Schmidt trigger that drive the final transistor Q4 (the switching transistor 2N3053).

This circuit is suitable for battery booster, if you need to run your 12 volt equipments on your old car that is provide only a 6V supply from the battery. The output of this voltage double can be adjusted by changing the voltage divider, or for easier adjustment, you can replace the 4,7K resistor with a 5K potentiometer. Using a good inductor (low resistance), you can achieve up to 80% efficiency, and up to 2 Watt power can be delivered to the load. [Circuits schematic diagram source: Bill Bowdens circuit collection]

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