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First coil gun, 6 cameras, which charge circuit?

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sidneylopsides

Tue Mar 01 2011, 07:33PM

Registered Member #3690 Joined: Mon Feb 14 2011, 10:59PM
Location: Leeds, UK
Posts: 11

Hi there, finally started getting parts together of a first build, I got 6 used disposable cameras from a shop today, 4 of them seem to have the same innards, the other two are both different.
The 4 that are the same don't have any specs on the caps, but I guess they are 330v 80/100uf, the other two are both 300v one is 100uf and one is 80uf.

Now, assuming I use one of the circuits as a charger, which is best? 5 are almost the same, one is much larger with wider tracks, I'd assume this would be best as it could handle larger currents through the PCB. This one has the 80uf cap. Though on the other hand, that one has steel or something for contacts, the others are copper.

These are the boards.

edit: I was also thinking could I use the charge LED power to trip a relay so it disconnects the charger when full, then automatically restarts after firing?

guitarlord66

Wed Mar 02 2011, 02:46AM

Registered Member #1805 Joined: Sat Nov 08 2008, 06:29AM
Location:
Posts: 67

Hey man

Definitely bank the 4 chargers in parallel, using one charger will be ridiculous charge time... unsolder the battery holders and the flash tube. Solder the button closed/down so that the circuit charges as soon as you have a voltage input and charge with no more than 3 volts, over 3 volts burns out SOME chargers. in my gun I have 10 similar or maybe even the exact same charges that you have (the 4) and they charge a 1140uf bank of capacitors in 8 seconds to 330v using 6 NICD cells at 3.6volts (parallel and series connection).

I have never disconnected the charger when firing, I just shoot and the chargers automatically start charging again.

Any more questions I'd be glad to help :)

sidneylopsides

Wed Mar 02 2011, 08:23AM

Registered Member #3690 Joined: Mon Feb 14 2011, 10:59PM
Location: Leeds, UK
Posts: 11

ah, cool! thanks :)
One other thing, I'm not sure about the charge indicator, would the one on the boards still work as normal?

guitarlord66

Wed Mar 02 2011, 09:23AM

Registered Member #1805 Joined: Sat Nov 08 2008, 06:29AM
Location:
Posts: 67

Yeah if the chargers are paralleled together the LED's on them will all illuminate at the same time :) They usually turn on around 280 volts though and stay lit how ever high you want to charge. I wanted to see if the chargers would overcharge the capacitors to the point of explosion, so I let them charge for over 5 minutes and they just sit at around 350 volts. I didn't have any problems with it at all :)
Also only parallel them if they are the same chargers, I don't know what would happen if they are different brands.

EDIT:

Here's some pictures from when I built my bank, I thought it may help :)

The untouched charger:

1UntouchedChargingCircuit

Untouched Charger next to stripped down charger:

4Comparisent

10 stripped down chargers, block of wood with slots to mount them in, copper wire and thick wire insulator to cover the wire:

5Materials

Finished Charger:

6Complete

I probably went a little over the top with it but I wanted it to look nice :)

sidneylopsides

Wed Mar 02 2011, 10:05AM

Registered Member #3690 Joined: Mon Feb 14 2011, 10:59PM
Location: Leeds, UK
Posts: 11

Thanks man! Those pictures look like what I had in my head when you said to put them in parallel. I have two circuits that look identical to yours, and two similar. Ill use the two identical ones for now, then so the nice lady at the camera shop for more!

guitarlord66

Wed Mar 02 2011, 11:03AM

Registered Member #1805 Joined: Sat Nov 08 2008, 06:29AM
Location:
Posts: 67

haha cool :) Yeah I went to get more today and the guy said there photo processing thing is down and the company that repairs them is bankrupt so he doesn't know if they will ever process film again :S

Good luck with your charger :)

sidneylopsides

Wed Mar 02 2011, 06:25PM

Registered Member #3690 Joined: Mon Feb 14 2011, 10:59PM
Location: Leeds, UK
Posts: 11

Oh that's not good!

Thanks for the help, the magnet wire is on it's way, going to work more on the circuit tonight.

sidneylopsides

Tue Mar 29 2011, 09:53PM

Registered Member #3690 Joined: Mon Feb 14 2011, 10:59PM
Location: Leeds, UK
Posts: 11

Been away from this a while due to other projects, well, competition, that I won :p
I now have a a few more cameras to play with:

It seems to work well if the girl in the camera shop needs an excuse to come see you at work... we're off a for a drink next week :p

So back to this, I need to find a trigger, the charging and cap circuits seem to be fine, just no good way of triggering it at the moment.

James

Tue Mar 29 2011, 11:28PM

Registered Member #3610 Joined: Thu Jan 13 2011, 03:29AM
Location: Seattle, WA
Posts: 506

The capacitors from those cameras are fine, but it's really a lot less work and more efficient to use a ZVS flyback driver with a self wound secondary. You can get ~300V from 20-40 turns at several hundred Watts if your power source can supply the current.

guitarlord66

Wed Mar 30 2011, 02:54AM

Registered Member #1805 Joined: Sat Nov 08 2008, 06:29AM
Location:
Posts: 67

sidney: use a relay or SCR to trigger it :)

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