Showing posts with label electronic power supply. Show all posts
Showing posts with label electronic power supply. Show all posts

Friday, 15 January 2016

Automatic simple 12V 100mA NiCd Battery Charger circuit

Today we are going to learn how to make a very cheap NiCd battery charger with overvoltage protection or control circuit. This circuit is very much simple and specifically designed for 12V NiCd battery. The charger have current and voltage control at the same time.

Its charging current is around 100mA but we can change it using the formula : (Vd1 - 0.7) / R2 ; where Vd1 is voltage of zener diode D1.

Its Cutoff voltage is limited to Vd2 - 0.7 ; where Vd2 is voltage of zener diode D2

Part List:-

R1 - 2.7 kilo ohms 1/4watt

R2 - 56 ohms 1Watt

D1 - 1N4735A or any 6.2V zener diode

D2 - 1N5244B or any 6.2V zener diode

D3 - 1N4001 or similar diode

Q1 - 9013, 2N2222 or similar NPN transistor

Q2 - 2N3440 or similar NPN transistor

Simply solder the above circuit and enjoy simple 12v 100 mA or change it.

For any further querry please ask them in comment section. I wil be happy to help.

Some basics of Electronic power supply circuits before building them.

Some of the Parts of a Power Supply are:

A DC Power Supply Unit or a power supply unit (PSU) is deriving power from the AC mains (ac or mains line110/220 VAC) supply performs a number of tasks:

1:-  It changes (increase or decrease, mostly decreases the level of supply to a value suitable for driving the load circuit.

2:-  It produces a DC supply from a AC supply.

3:-  It prevents any AC from appearing at the supply output terminals.

4:-  It will ensure that the output voltage is at a constant level or not, independent or irrespective of changes in following parameters:-

(a) The AC supply voltage at the supply input.

(b) The Load current drawn from the supply output.

(c) and Temperature.

To do these things the basic power supply unit or a PSU has four main stages, those are:-

Power supplies in recent times have greatly improved in reliability now but, because they have to handle considerably higher voltages and currents, they are often the most susceptible to failure of any part of an electronic circuits.

Modern power supplies have also increased greatly in its complexity, and they can supply very stable output voltages with or without a controlled feedback systems. Many of the times we incorporat a automatic safety circuit to prevent dangerous or disastrous over voltage or over current situations.

That's why the study of modern electronics basics is essential to understand the electronic systems today.


If you are considering building or repairing a power supply, especially one that is powered from mains (line) voltages the power supply CIRCUIT on this site will help you understand how many commonly encountered circuits work. However you must realise that the voltages and currents present in many power supplies are very dangerous and fetal, and can be present even when the power supply is switched off! At worst, the high voltages present in power supplies can, and from time to time really  do KILL.
The information provided on this site will not alone, qualify you to work safely on power supplies units or simply PSU. You must also have the skills and equipment to work safely.

Please act responsibly, the author Alok kumar of this information and owners of this site will accept no responsibility or liability for any damage or injury caused to persons or to any third parties, property or equipment arising from the use or misuse of the information provided on this websites which is