Hello sparky!

Projects / Misc

Disclaimer: 

The voltage I am playing with is at a dangerous level and the arc can easily jump 0.3". Please treat high voltages with a bit of respect. The ozone and UV from the arc isn't good for your health.

While waiting for the ionizers, I played around I did some measurements on the flash circuit in one of those disposable cameras. It turns out that the output voltage can go quite a bit higher than the 300V or so. I don't expect it to work this well.

One way of generating a high voltage source is to use a voltage multiplier with a high voltage AC source. I bought some 0.01uF 3kV caps from China as spares after fixing my scope. I also bought some 1N4007 high voltage rectifier (1000V) as they were cheap.

I made some "springs" out of the trimmed leads. The caps are divided into two groups. They are laid out side by side and solder just enough to hold them together.

A voltage multiplier looks like this. There are two rows of capacitors that are interconnected with diodes. 10 caps and 10 diodes makes a 5X multiplier.

The springs are used to hold and connect the leads together in this free form multiplier. The second row of capacitor goes on top in the opposite direction. I guess I should have connected the bare wire to the lower left terminal instead of top.

I stripped off some of the parts (large capacitor, flash tube) for safety. I also desoldered one of the leads of the rectifier to disconnect the rest of the high voltage circuits.

I connect the multiplier to the AC output. The resistor in mine is 82R instead of 220R. The following shows a 5X multiplier. The multiplier can be extended to a certain point by just adding more diodes and caps.

I swapped the header I had previously as the spacing was a bit too close so I could not control where it sparks. I bent the pins to form a spark gap of about 0.1". I also connected the bare wire to the right terminal this time.

I hooked up my bench supply and started getting sparks at around 1.2V. Each arc discharges the capacitor and the charge has to build up again. At around 1.5V, the current was 0.4A.

So according to this chart from here, the output is a bit below 5kV. My guess is around 3-ish. This means that the (loaded) AC output from the flash circuit is around 600V.

With the additional block, I now have a 10X multiplier. I have to change the spark gap a couple of times to now 0.3" (7.62mm). :)

It starts arcing at around 0.9V, so the output is round 9000V at this point.

This shows the corona discharge just below the threshold for arcing.

My old "Sparky" has a much beefier inverter (long exposure). The transformer was from a switch mode power supply and was driven from a MOSFET at 12V.  The 10X multiplier is sitting on bubble wrap for extra insulation. It probably has a higher voltage.

The ionizers eventually showed up, but their outputs are too weak.  I opened up one of them.

The primary and secondary windings (3 in series) are on separate bobbins for high voltage insulation. It also means that the primary can be modified too.

The ozone generator looks like a neon tube but with a pale blue glow and a wire mesh on the outside.

There was a blown transistor. Could have been me reversing the polarity or that way from the factory. The transistors are 2SC945 - generic NPN with a ECB pin out. I have replace them with 2N2222 and that seems to work.

The 0.1uF was supposed to be 630/400V according to the silkscreen on the PCB. It is supposed to be a film cap and there would be some circulating current in this topology. Haven't check if it runs hot - probably not given the low power.

The ionizer seems to start around 2.5V and uses 0.09A at 12V.

Ion wind experiment

I cut 4 strip of foam boards 0.74" x 6" (18.8mm x 152mm) from the dollar store. I glued a 0.5" (12.7mm) wide strip of aluminium foil and a couple of drain wires. This time I use a UHUstic glue stick. :)

The 4 pieces was stacked together and the drain wires twisted together forming the "ground" connection. Large sized popsicle stick I got from the craft section of a dollar store for scale.

On each end of the stack, I use hot glue to attach a piece of card board. I drill 4 holes that lines up with the aluminium foil.

I threaded a piece of 0.002" (0.05mm) dia of magnetic wire between the opposite side. The bendy cardboard helps to provide a bit of tension for the wire.

The wire is attached to the "hot" side of the multiplier.

One thing I notice is that the wire bends towards to aluminium when power is applied due to electrostatic force. I added a piece of foam in the middle to prevent the wire from bending. I added extra hot glue to electrically insulate corona spots on the foil and drain wire.

Power off:

The wind is a bit weak, but enough to lift the foil and the receipt on the left side The power supply is drawing quite a bit of power and the output voltage is below the arcing threshold. The transformer in the flash circuit is slightly warm.