15 Volts To 110,000 Volts

There’s something satisfying about creating high voltages. Sure, there are practical uses like neon signs or doing certain experiments, but be honest — you really just want to see some giant arcs lighting up your dark mad scientist lair. [Mircemk] has just the prescription for what ails you. Using a two-stage approach, he shows a simple setup that generates about 110KV from a pretty tame 15V supply.

From the 15V, there is a stage that uses a flyback transformer and a switch to generate a reasonably high voltage. The final stage is a Cockroft-Walton voltage multiplier that can produce quite a bit of voltage. You can see the impressive arcs in the video below.

The multiplier circuit found fame with experiments by Cockroft and Walton, obviously, but was actually originated in the early 1900s with a physicist named Greinacher. The circuit uses diodes as switches and charges a bank of capacitors in parallel. The discharge, however, puts the capacitors in series. Neglecting losses and loads, the output voltage is equal to the peak-to-peak input voltage times the number of stages present. Real-world considerations mean you won’t quite get that voltage out of it, but it can still provide a potent punch. Click through the break for a video of the circuit in action!

There are lots of ways to generate high voltages. Just be careful making measurements.

25 thoughts on “15 Volts To 110,000 Volts

    1. Each cap doesn’t have to be rated for the full output voltage since they will each only see a fraction of that voltage across them (the voltage multiplier consists of stages). Similar in the way that stacking caps in series in a dc system will have each cap charged to a fraction of the total voltage across the full series string.

        1. Yeah, that’s correct. In a Cockroft-Walton multiplier, each cap sees no more than double the input voltage. Given a decent safety margin the 30kV caps used should be suitable if the output from the flyback is no more than 10kV.

          1. Yes and no, right? It’s a spark gap but it’s only “transmitting” radio interference. I don’t know how they work and I need to read more. I suspect that it would have a fairly high wattage and maybe they are too primitive to tune to a specific frequency. So it might not even be legal to use with my dinky technician license.

          2. Ah jeez, now I understand. What I was thinking wouldn’t work for so many reasons. They’re too primitive. And it’s not legal to use damped waves to transmit anything, and furthermore they can’t transmit sound.

    1. Couple reasons – a flyback transformer operates at a high frequency (several 10s of KHz, possibly higher). This allows much smoother output. Running from mains directly would result in a relatively low frequency of pulses from the output. Second is safety – the mains in the US can deliver at least 10 amps at 120 V (1200 watts), and much higher in other parts of the world. A high voltage source connected directly across the mains would not be intrinsically current-limited, and could deliver a [very] fatal shock. The low-voltage transformer provides galvanic isolation, so the high-voltage side is not directly connected to the mains.

    2. First, for isolation from the mains.

      Second, you don’t want to do this at line frequency (50 or 60Hz.)

      You need large capacitors at low frequencies – and those are expensive at high voltage.

      You convert to DC, generate a high frequency signal, step it up with a transformer, then use the multiplier to go from high voltage, high frequency to much higher voltage DC.

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