Winding the inductors is easier than you might think! I used about 4 feet of 18GA Magnet wire to wind the inductors for this particular power supply. Each inductor has ~30 turns on it for an inductance of about 90uH. If you don't have magnet wire, 24 gauge stranded wire will work ok in this instance, as we are not going to be running very high frequency. The easiest thing to do is to cut off a suitable length of magnet wire, and just start winding them, being careful not to let the magnet wire kink, and making sure you get the turns snug around the core and with relatively even spacing. The most difficult part is starting the first few turns. Start by leaving about an inch long tail of wire, and winding the wire around through the middle of the core. after a few turns, the wire will kind of hold itself on, and it will be easier to tighten the turns as you go. Here is a picture of one of the inductors being wound:
You need two of these, identical to one another, one for each half of the power supply. Take your time and be careful, or you will end up with a mess of wire that will not work well, and will probably need to be thrown away. After you have wound them, trim the tails to about 1-1.5 inches, and remove the enamel (if you used magnet wire) from the wire, almost all the way to the core, leaving about 1/8". If you used stranded wire, then, I cant help you... Well, ok, just leave a manageable amount on there and strip it down and tin to where you need it when you put it into the circuit. An easy way to remove the enamel from magnet wire is to heat the wire with a lighter until it flames up and turns black. Then, using some fine sandpaper (200 - 400 grit) remove the charred enamel from the wire until you see the shiny copper underneath.
If you do not do this, you will not be able to make an electrical connection to the wire, and the inductor will not work properly. After you have removed the enamel, apply some paste flux to the copper and tin the exposed copper with your soldering iron. You should get a smooth coating of solder on the exposed copper, allowing you to make a good electrical connection to the inductor. If you have access to one, it is a good idea to check the inductor with an LCR meter to see that the value is right. The value is not terribly critical, but should be around 85-90uH.
Once you have these inductors, simply build the HV PSU per the schematic above. The only part you will not be able to get for the PSU from scrounging will probably be the MOV's across the emitter and collector of Q2 and Q3. These can be gotten from digikey for a resonable price. I used part number ERZ-V07D361 because I had some left over from another project, but anything similar will do, as long as the breakdown voltage is less than 400V and greater than 300V. If you do not include this part, you run the risk of popping Q2 or Q3 because of over voltage. How you construct the circuit is up to you, but be sure you make the connections between C1 and the inductors large, as well as the connections between the other terminal of the inductors and the collector of Q2 and Q3 also large. be sure the the connection from both the emitters of Q2 and Q3 are large as well. This is necessary because there are heavy currents that flow in these paths during switching, and we can help a bit with the dismal efficiency of this thing by keeping them large, low inductance, and low resistance. Note the wide fat paths I used to connect those parts of the circuit below:
A good way to do this, instead of blobbing up solder, is to use some of your de-soldering braid as the connecting wire. It is fat and has a lot of copper, allowing a low resistance, low inductance path for the large currents to flow. Once you have built the power supply, and double checked all the connections, you are ready to move on to the pulse distribution and control circuit. If you want, this power supply can be tested using a 555 and some logic gates or even a micro-controller to generate a 25-30% duty cycle pulse that triggers each side every other time, or, in other words, you drive A for one pulse, and B for the next pulse and back and forth between the two sides. A frequency of about 16 Khz(8 khz per side) seems to work well.
A high voltage will develop across C2, and you can measure it carefully with a multimeter to see what it reaches. It should be about 150-200V pretty easily, more is the duty cycle is larger. Be careful, as you can receive a nasty shock from C2 during, and even several minutes after the unit is powered off! If you have ever wondered what it felt like to be zapped by a photo flash unit (don't ask!), well, this will give you a taste, but doesn't have as much energy! IT WILL HURT! I PROMISE! Just trust me and be careful mmkay?
In the next phase, we will cover some basic theory and construction of the pulse divider circuit, and the touch-release sensor circuitry. Stay tuned, give skulls, follow and enjoy! Thanks!