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I have gone without a variable lab bench power supply for too long now. The power supply that I have been using to power most of my projects has been shorted out too many times. I have actually killed 2 by accident and needed a replacement. I had many 18650 lipo batteries lying around my workshop so I decided to use them to build a portable variable bench power supply that could be easily moved around and used on the go. The power supply consists of DC-DC step up power module, voltage and current display, a switch, standard size 10K trim pots, XT-60 and a balance connector for charging an array of 8x4 18650 batteries.

There are many types of power supply. Most are designed to convert high voltage AC mains electricity to a suitable low voltage supply for electronics circuits and other devices. A power supply can by broken down into a series of blocks, each of which performs a particular function. Each of the blocks is described in more detail below:

Transformer - steps down high voltage AC mains to low voltage AC.

Rectifier - converts AC to DC, but the DC output is varying.

Smoothing - smooths the DC from varying greatly to a small ripple.

Regulator - eliminates ripple by setting DC output to a fixed voltage.

This power supply eliminate voltage loss on current meter. Will be designed for measure on low voltage DC/DC converters (e.g. LED lamps powered from single NiCd/NiMH cell)

Modern power supplies are known as "switching regulator power supplies." In most switching supplies, the 110 volt AC input is first rectified by two diodes and filtered by a pair of capacitors. This creates two high- voltage sources; one positive and the other negative. A pair of transistors is then used to switch these high voltage supplies across the primary winding of a transformer. This switching action is very fast. A typical switching speed is around 40,000 cycles per second or 40KHz. An integrated circuit is commonly used to control the transistors. This IC not only controls the speed at which the transistors are switched, but also controls the amount of time that each transistor is energized. The output voltage of the power supply is determined by the "on" time of the transistors. If the transistors are keep on for a longer period of time, the output voltage of the supply will rise, while shorter times lower the output voltage. This is known as "pulse-width modulation."

The following diagram is provided for anyone who would like to include a voltage regulator but who does not want to use one of the ic versions (as in the updated, regulated supply for the 1996 design). This is a very basic regulator circuit, without any additional features such as foldback current limiting, and does not have the same performance as an ic regulator.

As the world around us becomes more and more environmentally conscious, alternative energies such as solar power are becoming more and more popular. The following solar charger is very simple and inexpensive to build and could be used to charge cell phones, tablets and other USB devices. 6V solar panel could be easily salvaged from outdoor garden lights. Solar charger uses REG113-5 efficient low dropout regulator that only loses 250mv of forward voltage. Linear style regulators such as a LM7805 or LM317 type voltage regulators lose as much as 2-3V and can not be used in this application. Optionally you may also add four-resistor voltage divider to charge an iPhone or iPad.

Split power supply provides a stable regulated bipolar voltage in the range ±1.5V to ±17V. It is based on LM317/LM337 linear voltage regulators that also have a short circuit protection. Most parts are easily accessible, including a 6"x3"x2" project box, 12V 1.2A center tap transformer, pots, knobs, etc. Power supply schematic shows how to wire LM317/LM337 to get +/- split voltage output.

Here is an efficient 4-stage stabilized power supply unit for testing electronic circuits. It provides well regulated and stabilized output, which is essential for most electronic circuits to give proper results. The circuit provides an audio- visual indication if there is a short circuit in the PCB under test, so the power supply to the circuit ‘under test’ can be cut-off immediately to save the valuable components from damage.

The power supply for the original 1969 JLH design included a form of capacitance multiplier to reduce the amount of voltage ripple on the supply rail. The capacitance multiplier circuit has been developed further, by Rod Elliott of Elliot Sound Products, and the results published as Project 15 at the ESP Audio Pages. The modified circuit is suitable for both the original 1969 JLH amplifier (using only the positive half of the circuit) and the 1996 update. The design considerations for the capacitance multiplier, its benefits, and a comparison with voltage regulators are included in the Project article.

Simple, low cost and easy to build power supply. Ideal for applications that doesn’t require too much power. It can provide power to circuit that uses less than 100mA without any problem. The disadvantage of this circuit is the danger of an electrical shock, so it cannot be used if the circuit is in contact with the user. The voltage supplied by this is determined by the zener diode.