Now, lets have a look at the circuit schematic, and understand how it works .(see schematics after the description)
1.At the left you will find the main input of 220VDC, which will arrive to a bridge rectifier. If you cant find a bridge rectifier, you can build one very easily, using 4 diodes, as the schematic explains.
2.From this rectifier we have two outgoing wires: the positive and negative. They provide ~300-350 VDC to our circuit.
3.Cut the negative wire, and insert a fuse to protect our project.
4.For the positive wire, use a resistor instead, the resistor will limit the current, so the capacitors charge will be regulated and not too violent.
5.After you have connected the fuse on the negative wire and the resistor on the positive wire, connect the main storage capacitor(s). Positive to positive and negative to negative. If you use several capacitors, they should all be connected in parallel.
6.From this point those two wires will feed the flash tube with power. Make sure you use well insulated wires, thick enough to carry decent power. This circuit will surge several hundreds Amps (depending on your setup), from the capacitor to the tube in the moment of firing.
7.Connect the two wires to the tube’s electrodes. Check if your tube has a polarity, and respect it.
8.Now, as you can see, on the schematic you have to get the triggering system together. Connect the small trigger capacitors with its resistor as shown, and the trig. transformer’s common wire (thick) to the NEGATIVE main wire.
9.From now on, you have two wires that will command the triggering (the one coming from the trigger capacitor (thick), and the one coming from the trig. transformer (thin)). These wires have a potential of around 350v, which will be harmful to your camera’s PC Sync port. So.... you have to insulate this high voltage.
10.Using an optocoupler and SCR, connected as shown above, you will have, again, two wires going to the camera’s PC Sync port, but now with a few volts potential only, which is safe for your camera.
11.Please note that a power source of ~6 VDC is needed to feed the optocoupler. Hacking a small cellphone transformer, is the best solution. It will integrate all power sources in your project box. If you dont have a cell phone charger at hand, feel free to use simple batteries to reach 6V. The consumption will be close to zero! The optocoupler will draw only some 20mA for about 1/200 a second every time the flash is fired.
12.Finally, the second (thick) wire of the trigger. The transformer will be connected directly to the flash tube TRIGGER terminal.
Try to keep this wire the shortest possible, even locating the trig. transformer right near the tube. This wire will supply a several Kilo-Volts, keep it well insulated, and spaced from other components.
source :
Studio Lighting - DIY: Home-made Power Pack Flashes (Part I) | DIYPhotography.net
Originally Posted by coolguy22
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