DEVMO2PCS DC 3V-6V to 400kV 400000V Boost Step-up Power Module High-Voltage Generator

Just testing the first one seems to be working well. 3V in pulled ~9 watts (~2 amps), I put a 5 ohm 10 watt resistor on it so it hopefully won't cook itself.

Nowhere near 400KV, obviously. The description suggests a maximum 20mm spark gap which indictates more like 60KV but I wouldn't try it, personally. Regardless, these things rock!Having done some testing, I don't suggest over-driving these units. They push hard enough at 6V and won't survive being abused. That said, here are the data I've collected from a single randomly selected unit (1 of 5)3V > 1.9KV4V > 3.3KV5V > 5.5KV6V > 7.0KV7V > 8.3KV8V > 9.7KV9V > 11.1KV10V > 12.3KVIn my opinion these units are best driven at 5V for an 1100x increase to 5.5KV as more input power, even 6V, hardly increases the multiplication factor and dramatically increases the stress on the components even producing a high pitched squeal that would go unheard during normal use as the sparks are LOUD, and likely go unrecognized until the unit fails.Overall, I love these little monsters and highly recommend them of you like inexpensive fun! Just be safe, don't abuse them and temper your expectations. 400KV would jump over 5" easily and my gap is only 3/8" in the video. Still, super fun :)

They worked perfectly to really make my taser really arch

Major Warning!!! Treat these modules with respect. They will set you on your you know what if you aren't very careful. A *brief* touch to a 9 volt battery will pop out an inch long spark and a loud snap. They are NOT rated for 9 volts, and operating in that range will destroy them quickly. The dielectric properties of insulation are absolute. Exceed it, and it perforates. Period. I marked the module I tested, and plan to discard it. They are also not rated for high current, so include a (high voltage) resistor in your final circuit. Remember that at 400 kilovolts, it only takes a current of 0.0025 milliamps to produce 1 watt of current. And that would probably be about the limit to these, unless someone wants to do some destructive testing. Quarter watt resistors aren't going to do the job, which is why I said HIGH VOLTAGE resistors. If you don't run them continuously, and don't exceed the input voltage constraints, great. Just don't complain when they stop working.

I tested these using a hydrogen spectrum tube as the load it creates is very stable compared to a spark gap. These tubes require only 3-5 kV so the output is obviously nowhere near to 400kV. At 5V in the current draw was close to 4A. It started getting slightly warm after less than a minute - I have not tried running it for longer.