I'm working on a small (ish ) disk launcher for my physics teacher. I plan on using a bunch of photoflash capacitors from old disposable cameras for the cap bank, but the problem is charging them all. I could use a camera charger or two but that would be a pain in the but to rig together, and I'm not sure if they will interfere with each other or not. Ok, so DC-DC conversion would be a pain, and I want to keep this cheap. So I figured I'd use house current for this. I would think that this would work. But spice tells me otherwise. The thing that makes me wonder is that without C3, I get 315 volts from the bottom of C2 to the top of C1. But when I add on C3 without a switch, it drops to 50 volts or so. I think it is just Circuit Maker being stupid, and that it would work fine in real life. The switch in there isn't the switch for switching the load, it just merely changes between charge and fire settings. I will have a different switch for the load. Oh and before any regional household power confilcts come up, I live in the US, and in the kind of outlet I intend on using, there is 120 vac, 60 hz, single phase. Thanks for the help.
With high power electronics, "If you don't know what you're doing, don't do it." However, there is a reference for you to use. http://repairfaq.ece.drexel.edu/sam/strbfaq.htm
Took me a few minutes, but here's some fine advice for working with mains, and/or high voltage charged circuits: http://repairfaq.ece.drexel.edu/REPAIR/F_safety.html
Could you not just build a voltage multiplier out of capacitors and diodes, would be able to source your 300vdc that way but i dont know how much current you could pull from it, using a current mirror you could control how much was being fed to the photoflash capacitors in your circuit so as not to stress it, but may restrict fast firing. Col
this may be usefull but I've got no idea what parts there are http://home.golden.net/~kpwillia/minich.htm
I can't even work out which coils are wound on that transformer, but I would be interested in knowing the part number of that 3pin device. Back onto the original circuit... my word that one frazzled my brain a bit.. I think it won't work, if you re-draw your circuit, as two circuits, for the two DC cycles which make up the AC cycle (eg no diodes) The first thing you'll notice, is that putting in C3 creates a circuit which will negitively charge the capacitors C1 and C2 depending on the cycle it's in. This stored voltage then affects the next cycle, to what effect I can't really tell without frying my brain a lot more but the negitive charges which appear on C1 and C2 could cause a significant drop in the voltage accross C3. I think my therys fine, but then I havn't got spice working, so can't really see if my theory is correct.
I know what I'm doing, its just that simulating it in circuit maker didn't give results anywere near what I expected, so that was causing some confusion. Oh well if I have 30 disposable cameras apart, I might as well rig up 30 parallel chargers... I'll have them allready, and he has a DC powersupply, so we won't have to rely on batteries, and we can up the voltage a tad too. And I see what your saying NoMercy. I love how you can have things work in your mind, bend the rules. But then reality comes and smacks you with all of the rules. Thanks all, hopefully I can get this working the way I want it.
Apparently you live in the US, so you have 120VAC in the house. Multiply by sqrt(3) for the peak voltage and you get 208V. Double that with a simple voltage doubler as shown at the top of http://www.kronjaeger.com/hv/hv/src/mul/ (Greinach, version a) and you get 416VDC. Your caps should still work since each of the two banks only gets 208VDC. The two Diodes should be 1N4007 or similar. I suggest that you eliminate the transformer. Instead you connect a 47kOhm/1W resistor from the "hot" wire to the two diodes and the other input lead from the circuit to neutral. Do yourself a BIG favor and plug the whole thing into a ground fault protected outlet. The resistor should only pass 3mA, which isn't lethal or even uncomfortable, but don't count on it.
