Simple project to deliver high-voltage at high-current to a DC load, controlled with PWM. In real-life application, the load is 5 series-connect 100W LED. updated June 01, 2016The simple configuration of a transformerless power supply circuit presented below is able to provide high current at any assigned fixed voltage level. The idea seems to have solved the problem of deriving high current from capacitive power supplies which earlier seemed a difficult proposition. I assume I am the first person to have invented this. UPDATE:  A better and a more advanced design can be learned in this zero crossing controlled surge free transformerless power supply circuit A neatly drawn PCB for the above high current transformerless power supply may be seen below, it was designed by Mr. Patrick Bruyn, one of the avid followers of this blog. Update (August 22, 2014) A deeper analysis of the circuit showed that the triac was dumping a significant amount of current while restricting the surge and controlling the current.

The approach taken in the above circuit for controlling voltage and the surge is negative in terms of efficiency. In order to obtain the intended results as proposed in the above design and without dumping precious amps, a circuit with exactly opposite response needs to be implemented, as shown below: Interestingly, here the triac is not configured to dump power rather it's wired in a such a way that it switches OFF power as soon as the output reaches the specified safe voltage limit, which is detected by the BJT stage.heat pump unit dripping waterWhat is a power supply?5 ton ac unit commercial supplies power to another device, at a specific voltage level, voltage type and current level9VDC @ 500mAas much as 500mA of current9V DCac power supply khz

Why a power supply?When you start out with electronics, you'll hear a lot about power supplies - they're in every electronics project and they are the backbone of everything! A good power supply will make your project hum along nicely. A bad power supply will make life frustrating: stuff will work sometimes but not others, inconsistent results, motors not working, sensor data always off. Understanding power supplies (boring though they may be) is key to making your project work!A lot of people don't pay much attention to power supplies until problems show up. We think you should always think about your power supply from day one - How are you going to power it? How long will the batteries last? Can it get damaged by accidentally plugging in the wrong thing? Power supplies are all around you!Unless you live in a shack in the woods, you probably have a dozen power supplies in your home or office.Here is the power supply that is used in many apple products: All these power supplies have one thing in common - they take high voltage 120V or 220V AC power and regulate or convert it down to say 12V or 5V DC.

This is important because the electronics inside of a computer, or cell phone, or video game console dont run at 120V and they don't run on AC power! So, to generalize, here is what the power supplies for electronics do: They convert AC (alternating current) power to DC (direct current) They regulate the high voltage (120-220V) down to around 5V (the common voltages range from 3.3V to 15V) They may have fuses or other overcurrent/overheat protection Hey, so if electronics can't run on AC, why doesn't wall power come in DC? You may be wondering - "I have 20 wall adapters, this seems silly! Why not just have DC power come out of the wall at 5V?" Essentially, because modern electronics are very recent. for many many decades wall power was used to power light bulbs, big motors (like fridges, vacuum cleaners, washing machines, air conditioners), and heaters. All of these use AC power more efficiently than DC power. Also, different electronics need different voltages.

So far its worked out better to have a custom power supply for each device although it is a little irritating sometimes! High Voltage AC (eg. 120V-220VAC) Low voltage AC (eg. 12VAC) Really cheap, electrically isolated Really big & heavy! Small motors, in cheaper power supplies before the regulator Low Voltage AC (eg. 20VAC) High voltage AC (eg ~120VAC) Same as above, but the transformer is flipped around Some kinds of inverters, EL wire or flash bulb drivers High voltage DC (eg. 170VDC) Half or full wave rectifier Very inexpensive (just a diode or two) We've seen these in tube amps Low voltage DC (eg 5VDC) Practically all consumer electronics that have transformer-based supplies Transformer & rectifier Combination of High→Low AC & Low AC→Low DC Kinda heavy, output is not precise, efficiency is so-so Every chunky wall-wart contains this Light-weight, output is often precise Every slimmer wall-wart contains this

Basically, to convert from AC to AC we tend to use a transformer. To convert from AC to DC we use a transformer + diodes (rectifier) or a switching supply. The former is inexpensive (but not very precise) and the later is expensive (but precise). Guess which one you're more likely to find in a cheaply-made device? We left a few types out of this table because they're a little more esoteric or complex, such as the AC voltage doubler. These are still used but you're a little less likely to see them and they don't get used in power supplies you're likely to encounter.Some radios work on both alternating current (AC) and directed currentthis was rather common for the smaller table radios, but for larger radios like the Pye P445U on the right it is more the exception. AC/DC radios do not have a power transformer, but rather rectify the incoming mains power directly; this saves the space for a transformer and, moreover, the considerable cost. In Dutch, AC/DC radios are referred to as `Universeel-toestel'.

As a consequence of the design, the chassis of the radios is connected directly to the mains, and they require special care when servicing them or playing them with the cabinet open or removed. Indeed, safety requirements were less severe a couple of decades ago, and nowadays production of these radios would be prohibited without any doubt. As long as you know what you are doing, but only then, there is no immediate reason to throw (or give, hint hint!) the radios away. For anything beyond the most elementary repair, work on AC/DC radios requires that the radio is supplied from an If the transformer can be switched to 110V (like mine) you can also use it for American radios or play a European one without heating the Unless you are very sure about what you are doing, don't even look at the inside of AC/DC radios without using an isolating Only with this unit an AC/DC radio can be connected to measurement tools or even, be touched, safely.

Many of the AC/DC radios are quite simple and have no external connections except for an antenna. Barring the unusual power supply, the circuits used in AC/DC radios are very much like those found in the smaller AC-only radios. All external connections run through capacitors, which should be carefully checked and replaced if their DC resistance deviates Before taking the unit into regular use, be careful to check that no metal parts, connected to the chassis or the wiring, can be touched The Erres depicted on the right was designed very carefully: even when the knobs are completely gone it is not possible to touch any metal part, but the popular Tesla Talisman have their hot parts touchable in Be extremely aware when the knobs have been replaced or modifications have been carried through: the new knobs or added controls may Don't put the set into regular use without the back and bottom parts It is better not to use these radios in damp areas such as the

bathroom (;-) or kitchen. Some more technical points regarding the AC/DC radios. The heaters of the (usually four or five) tubes are connected inIn the European radios the common heater current is 100mA (tube type numbers start with U), while in the American radios the current is usually 150mA. The heater voltages add to usually 110 or 120V. In those radios that can be played on 220V (almost all European radios) a large dropping resistor is used in series with the heaters. This large resistor dissipates about 10-12 Watt and becomes very hot. It sometimes contains asbestos. When the resistor needs replacement you can put new resistors, but it also becomes increasingly popular to put a series capacitorcompute the value with the CapCalc spreadsheet in 10 seconds! I did so in my Philips 208U to reduce the amount of heat produced in the small cabinet. AC rectification in transformerless radios is half-wave