Panto props
Nov. 24th, 2014 10:12 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png)
Okay, just one prop.
But it's a rather interesting problem, and one that's taken me two weeks to get to even a moderate understanding what the problem is...
I've already mentioned on here about the idea I'm working on for a remote sound-effect trigger system.
Well, our director noticed how (seemingly) adept I am with electronics, and on November 8th approached me with a supposedly simple problem.
You see, we feature our fairy queen with a magic wand prop, which gives off a bright flash when its button is pressed. The flash is bright enough to be seen in the back rows of the theatre, but not bright enough to blind the fairy.
Anyway, apparently our current fairy queen was taking last year's decorations off the wand when she accidentally broke the ball off the end.
You know, the ball that contains a flash circuit board from an old film camera?
She broke the wires off the circuit board, and the question was how to get it back in working order.
My initial response: Yeah! Sure! I'll have it done by next week!
Yeah, no.
The circuit board was taken from an old film camera, and therefore not intended to be used in the manner we have been, so the pads I'm supposed to solder the wires back onto are not marked, which in turn meant that I had to follow the traces on the PCB by hand.
(yes, I checked. The part number on the board didn't show up anywhere online)
Anyway, after finding about half-a-dozen different schematics for various brands of old xenon-type flash units (none of which matched mine), I finally (thought) I'd figured it out and decided to move all the components to a new board.
Unfortunately, it didn't work, and I then moved only the parts responsible for charging the capacitor back to the original board, where it worked again.
(turns out I'd missed a connection)
My current plan is (as I'm still not finished it yet) to use both boards to make it a more compact package, incorporating a plug and socket between the wand itself and the flash unit so we can have a backup flash unit.
(and hopefully this won't happen again)
I wired the whole thing up again in a temporary manner on my workbench (aka, my bed with a board overtop) and it works again! =^.^=
Next up is to move the charge LED (now a bright white one instead of a tiny green one) next to the flashbulb, lower the value of the resistor right beside it, and wire the boards together properly.
But it's a rather interesting problem, and one that's taken me two weeks to get to even a moderate understanding what the problem is...
I've already mentioned on here about the idea I'm working on for a remote sound-effect trigger system.
Well, our director noticed how (seemingly) adept I am with electronics, and on November 8th approached me with a supposedly simple problem.
You see, we feature our fairy queen with a magic wand prop, which gives off a bright flash when its button is pressed. The flash is bright enough to be seen in the back rows of the theatre, but not bright enough to blind the fairy.
Anyway, apparently our current fairy queen was taking last year's decorations off the wand when she accidentally broke the ball off the end.
You know, the ball that contains a flash circuit board from an old film camera?
She broke the wires off the circuit board, and the question was how to get it back in working order.
My initial response: Yeah! Sure! I'll have it done by next week!
Yeah, no.
The circuit board was taken from an old film camera, and therefore not intended to be used in the manner we have been, so the pads I'm supposed to solder the wires back onto are not marked, which in turn meant that I had to follow the traces on the PCB by hand.
(yes, I checked. The part number on the board didn't show up anywhere online)
Anyway, after finding about half-a-dozen different schematics for various brands of old xenon-type flash units (none of which matched mine), I finally (thought) I'd figured it out and decided to move all the components to a new board.
Unfortunately, it didn't work, and I then moved only the parts responsible for charging the capacitor back to the original board, where it worked again.
(turns out I'd missed a connection)
My current plan is (as I'm still not finished it yet) to use both boards to make it a more compact package, incorporating a plug and socket between the wand itself and the flash unit so we can have a backup flash unit.
(and hopefully this won't happen again)
I wired the whole thing up again in a temporary manner on my workbench (aka, my bed with a board overtop) and it works again! =^.^=
Next up is to move the charge LED (now a bright white one instead of a tiny green one) next to the flashbulb, lower the value of the resistor right beside it, and wire the boards together properly.
no subject
Date: 2014-11-25 10:48 am (UTC)Your knowledge of the working of integrated circuits is most impressive. I wish I had any expertise to contribute. Hope you're able to resove this.
no subject
Date: 2014-11-25 12:16 pm (UTC)I'd found a few websites that have information on Xenon flash and/or strobe units, including one or two that dealt specifically with disposable camera flash units.
Almost all xenon flash units are built the same way, a high-frequency oscillator (whose design varies pretty significantly, from what I can tell) that drives a step-up transformer, which uses a single diode to rectify the current so it can charge a capacitor.
Once charged and/or manually triggered, a second, still smaller step-up transformer boosts a small fraction of the capacitor's charge enough to allow the xenon flashbulb to use the rest of the capacitor's charge.
Simple, no? =^.~=
Surprisingly enough, there are only two components even remotely similar to an integrated circuit.
A transistor (for the oscillator) and a diode (for charging the capacitor).
It's taken me over two weeks to get to this point, but now that I'm here it feels really good.
I've managed to get it fully working again, though I'm slightly concerned with how much space it takes up.
We'll see what the props mistress and the director think about it this Saturday...
no subject
Date: 2014-11-25 07:44 pm (UTC)no subject
Date: 2014-11-25 08:01 pm (UTC)Unfortunately, I leaned more towards digital circuits than analog ones, so much of the extra time this took was remembering how analog ones worked.
(well, that and the fact that most of the schematics I found had multiple transistors, and having one that had only one was rather puzzling)