switcher that convert AC voltage to a higher DC voltage

If you need high voltage, a voltage multiplier is one of the easiest ways to get high voltage. A voltage multiplier is a special type of rectifier circuit that can convert AC voltage to a higher DC voltage. They were invented by Heinrich Greinacher in 1919, and they were used in the design of particle accelerators that performed the first artificial nuclear decomposition, so you know they are important.
In theory, the output of the multiplier is an integer multiple of the AC peak input voltage. Although they can work at any input voltage, the main purpose of the voltage multiplier is at very high voltages, in the tens of thousands or even millions of volts. Order of magnitude, need. Their advantage is that they are relatively easy to construct and cheaper than equivalent high-voltage transformers with the same output rating. If your crazy science needs sparks, maybe a voltage multiplier can provide it for you.
The multiplier circuit requires AC power to work. For simplicity, assume that one side of the power supply is grounded and maintained at zero potential, and the other side changes between positive and negative U (100 V in the example). This is what happened:
As we have seen, we will end up with 400 V between ground and output (points a and b in the last figure), effectively quadrupling the supply voltage.
This is an idealized explanation. As you might guess, reality is always more complicated. For example, capacitors are not charged immediately, so they will not reach full voltage until a few cycles have passed, depending on the charging current that the power supply can provide.
The multiplier we just discussed has two stages. Each stage consists of two capacitors and two diodes, each of which increases twice the voltage of the power supply, so for example, the output of a five-stage multiplier will be ten times the input voltage. Note that each component in the circuit can only see at most twice the peak input voltage provided by the power supply, so you can use low-voltage components and multiple stages to get a very high output voltage.
However, according to this formula, as long as the load is connected to the circuit, the output voltage will drop. Here we can see that we need high frequency and high capacitance to minimize the voltage drop, and this drop increases with the increase of the current, and also very fast with the increase of the number of stages. In fact, since it depends on the cube of the number of stages, the voltage drop of a 10-stage

multiplier is 1000 times that of a single-stage multiplier.

Another situation that occurs when a very high voltage is present is a corona discharge, which is a discharge that occurs when the electric field strength around the conductor is sufficiently high. The corona acts as an unwanted load on the multiplier, thereby reducing the output power. One way to reduce corona is to reduce the curvature of the conductor, avoid sharp corners, protruding points, and small diameter wires. For this, large-diameter terminals and conductors are used. This of course complicates the design of very high voltage multipliers, but it also illustrates their impressive appearance, as shown in the characteristic images.

Self-made voltage multiplier, made by [rmcybernetics] to obtain high voltage is a popular project, as long as the voltage is not so high that corona starts to cause problems easily. In addition to the AC power supply (such as a neon transformer), you only need some high-voltage diodes and capacitors. Practical uses include X-ray machines, photocopiers, air ionizers and microwave ovens. The high end of the spectrum is the multiplier used for particle accelerator research, which can reach a height of several meters and reach millions of volts.
The high-pressure multiplier has a long history in particle accelerators, and even the Nobel Prize in Physics has been awarded for its research. However, with the advent of new technologies, especially RF quadrupole systems, those magnificent multipliers have been retired. We will definitely miss them, and of course this will not prevent you from building your own.
A dead-time voltage multiplier can be a very beautiful work of art! A burned out CFL lamp is sometimes used as a power source. Don’t forget the silicone wire and mineral oil.
These are suitable for very high voltages. Most diodes (from the parts box) have a breakdown voltage of 1KV or lower. Therefore, they connected some in series for higher voltages.
Or you can remove the diodes from the old microwave, but you will have to purchase 11 or more microwaves.
If I connect diodes in series, such as 1N4001, for high voltage, I have to connect a 1M resistor in parallel with each diode so that one of them will not “run away” and take up most of the voltage and self-destruct.
Only when the input frequency is 60 cycles or less. For higher frequencies (and higher powers), another high-voltage fast diode is required.
Not really needed. Diodes will not be disconnected from the overvoltage immediately, they will begin to leak some current first, and if the voltage continues to increase, they will enter an avalanche breakdown. If a large current is allowed to flow (low source resistance), dissipation (high voltage * large current) will damage the diode.
However, if the total voltage is not evenly divided by several diodes connected in series, the diode with the highest voltage across it will start to leak more current than the other diodes, thus restoring the voltage balance, because the leakage current will cause the voltage across that particular diode The diode drops, while the voltage across the other diodes increases.
Of course, you do need to include some safety margin; it would be bad to use 10 diodes rated at 1kV for a 10kV power supply; once one of the diodes undergoes an avalanche breakdown, the voltage across it will drop rapidly, resulting in the voltage of the other diodes It will rise until the avalanche breakdown of another diode, and soon everything will catch fire. For a 10kV power supply, I will use 14-16 diodes in series, each with a rated voltage of 1kV.
Of course, a safety margin is also good, I will choose >=20%, and of course 50% is also good. But “avalanche breakdown” does not mean that it behaves like a spark gap or DIAC. It behaves like a Z diode, clamping voltage.
The diode will not self-destruct, it will start to work like a Zener diode and limit its voltage, so the other one in the string takes over
A 1,000 volt Zener diode does not require much current to self-destruct! The rated value of the diode is the heat generated by the forward current and the forward voltage drop. A 1A diode consumes 0.7 watts of heat at full load. When performing Zener at 1,000 volts, 0.7 watts is achieved with 0.0007 amps. If the diode determines the zener with a good large capacitor in parallel, you can guess what will happen next. You get fireworks.
Jermaine, the leakage current of the diode is usually on the order of 10^-15 A. As long as their final leakage current is less than 10^-14 A, everything will be fine.
Jermaine, there is no spark gap like malfunction. The upper limit will limit the rate of voltage rise, and the diode will gradually begin to conduct some current. When it gets hot, it even increases its breakdown voltage. Therefore, the capacitor cannot suddenly dump its charge into the diode.
A very easy to understand way to explain this circuit is through a small video of the correct stairs/escalator/elevator. Unfortunately, I cannot find your YouTube video.
The variant in my mind was used a long time ago. I consist of 2 adjacent ladders, and they all move up and down 20 cm to 1/2 meter. When one goes up, the other goes down, and vice versa. You can move up (or down) by walking from one ladder to another when appropriate. Does anyone know how this is called? Youku link?
Some oversized multipliers were built, starting from about 30Kv, and capable of throwing a good spark within 200mm. I found that the best option is to put the multiplier in the transformer oil. Many years ago, I made an ion gun in this way using an old car strobe light housing. The downside is that the launcher is not far forward and the trigger is less than 200 mm away from the launcher. The first and last shots using the trigger are a bit shocking.
However, one of the coolest uses is to put a small Z-shaped rotor on the pin at the end, make the device upright, turn it on and watch the rotor spin quickly at the point where the negative ions are thrown away. Then watched the dust in the room being sucked towards the shell.
When I was a radio amateur in my early years, circuits like this were called bridge rectifiers. They allowed me to obtain voltages as high as 900 to 1200 volts from a TV transformer intended to generate 450-600 volts.
This is actually closer to a half-wave bridge than anything. If you look at the Wikipedia article on Cockroft-Walton Generator, you will find that you are actually viewing half of the full multiplier. If using true AC sine (with zero crossing) drive, it is best to use the full wave variant. (Https://en.wikipedia.org/wiki/File:Full_wave_Cockcroft_Walton_Voltage_multiplier.png)
These don’t actually have to be driven by sine waves; low-pass squares are equally effective (although in some cases slightly less efficient)
Voltage multipliers were once used in televisions. A multiplier can obtain approximately twice the peak line voltage of the horizontal output. Sometimes another voltage is added to the flyback output to increase the voltage of the second anode of the CRT. I think this is to reduce the cost of the flyback transformer.
Interestingly, I always call them Cockcroft-Walton multipliers. When researching a cosmic radiation detector based on a photomultiplier tube to be used in space, we encountered a noise problem caused by a 1000V+ corona discharge in a vacuum. The solution is a 10-stage CW multiplier, each stage provides a 100-volt dynode to the 10-stage photomultiplier dynode voltage drop. The PM socket is removed, the CW is directly manufactured on the PM wire, and then the entire shebang is coated with primer, and silicone rubber is potted onto the tube. All PM tubes provide a voltage of about 100VAC and 100KHz, so very small CW capacitors are required. The 100VAC sine wave power supply did not bring us corona noise problems! We took the first batch of satellites to leave the earth’s orbit. About 12 years later, that spiral to the sun passed the earth, giving us another 100,000,000 miles of data! All 3 CWs are still moving forward. Hazza! Hazza! The CW multiplier continues to exist in outer space!
Try to explain general conditions such as surface impedance, corona, and high voltage to current PCB manufacturers… Yes, they just don’t understand.
So the higher the frequency of the AC input power, the better? I want to know that because solid-state power amplifier chips can handle very high loads and high frequencies, it may not be difficult for DIYers to customize high-frequency AC power supplies.
Car stereo power amplifier will work very well. Find a suitable switching power supply to power it, connect the signal generator to the input, and then you have the speaker output. Connect an ordinary transformer as a booster and add your multiplier. Ordinary transformers can handle audio, but don’t be greedy when you increase the frequency. You will get eddy current heating and waste energy.
I have always used an old stereo + laptop as my high-power signal generator. They have built-in overload, easy to control the output, if you blow up a channel, there are 1 – 3 spares, depending on the model. I happily drove everything from LEDs to DIY foil/ribbon speakers.
5 million volt Russian voltage multiplier-I would love to see it for myself. http://www.dailytech.com/Pictured+Drone+Survives+Flyover+of+Russias+Largest+Artificial+Lightning+Generator/article37172.htm
My first HeNe laser (in the 1960s) used a voltage multiplier in its power supply. It is troublesome to start the laser because the power supply does not provide enough current.
It reminds me of Real Genius bridge substation and “always check your optics”. Glad you can do things with what you have instead of turning us into popcorn.
Oh, cute, reminds me of my days at ABB HVC. When I saw their test laboratory for the first time, my first reaction was, “Gosh, they have Tesla coils!”. It is “interesting” to perform lightning/destructive testing on high-voltage cables (such as cables that import/export electricity between countries).
I saw pictures of places like this and thought “how cool it is to work there”. So is it or something else that is detrimental to the giant insect killer?
Very cool, especially when moving around the small cable drum (~25 tons) by hand. In addition, cable cutting is a bit interesting.
(I cannot use my own photos due to the confidentiality agreement, so I have limited publicly available things) http://www04.abb.com/global/seitp/seitp202.nsf/e308f3e92d9a8fc5c1257c9f00349c99/ca1a4ac2462c7494c1257960004baa6d/$FILE/cable_4794%20 %20300dpi .jpg
The orange thing in the background is the “snare drum” http://www07.abb.com/images/librariesprovider51/jobba-hos-oss/examensarbete_1183x35089f536e3c1f463c09537ff0000433538.jpg?sfvrsn=
A “big drum” http://www04.abb.com/global/seitp/seitp202.nsf/0/943ab3f8e3fbab3bc1257c7c00484f5f/$file/Dudgeon+cables.jpg
Great post, one part I hope is the comparison with the DC-DC charge pump. It is very similar, but you don’t need a clock with AC input! I know, I know, Wikipedia has placed the charts side by side.
I think this might be useful for bicycle generator circuits. Normally, your generator has a rated voltage of 6VAC, but depending on the speed, you can get 5-7V. You can easily rectify and feed the linear regulator, but the low efficiency in this application will be used as the resistance of the generator, which ultimately means that you step harder at the same speed! So efficiency is very useful here. Therefore, you want to use a DC-DC converter, but if you try to output a 5V voltage, the voltage drop of the step-down switch will be very low. In order to get good performance, you ultimately need boost and buck or other things, which are more complicated and less efficient than direct buck.
The voltage multiplier shown here is also a rectifier, so it may be reasonable to use it to double the voltage, so only a simple step-down switch is needed to obtain the low dropout voltage. I just learned on Wikipedia that the “120-240″ switch on the power supply does just that; it converts the rectifier into a voltage doubler!
This is more commonly used for high voltages,

but this circuit is also useful for DIYers when dealing with low voltage AC power!
Voltage doublers also bring some inefficiencies: First, each diode will drop at least 0.2 V (if you use Schottky diodes). In addition, at the low AC frequency of a typical bicycle generator, you will need a large-capacity capacitor to power any equipment that is more demanding than a bicycle computer.