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flying_silverad

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I have gutted a disposable camera (got it for a buck at dollar store:D ) and isolated the strobe circuit board and tube. Everything works great so What I want to do now is create a switching circuit that I can solder into where the switch used to be so that it will set off the strobe every 5 seconds or so. Any ideas or schematics?
 

BlueNinja

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I would use a 555 timer. Once you study a few pages on them, it becomes real apparent how to wire em'.
 

Hospital_Rocket

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Originally posted by Blue_Ninja_150
I would use a 555 timer. Once you study a few pages on them, it becomes real apparent how to wire em'.
The only challenge you would face is that a NE555 is an open collector to ground type output. This means you would need to tie the output thru a suitable resistor to Vcc . If I did my sums right that would be

Given: Vcc = 6Vdc

Max current = 200mA

Rout = 68 ohms (this is a standard value and will result in a 88mA current sink.

Now you have a signal - what to do with it...

I would strongly recommend a solid state relay to close the circuit. These are available from Digi-Key for about $3 each. Just make sure you have a DC/DC device.

A good chhoice would be an Aromat AQV210EH (Digi-Key 255-1145-5-ND)
 

FredA

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I would NOT recommend a 555.

Why - it's not going to work at the 1.5V supply of the Kodak strobe.

Just let the strobe self-fire using the NE2 bulbs as shown.

If you must fire it using a timer - use a pair of cross-coupled transistors to make an oscillator that will run at 1.5V. Then wire this to an SCR as the trigger. No need to use fancy SSR's.

I just finished a "night nosecone" for a rocket I intend to launch next weekend on a K1000-SK. It has a series of LED's and strobes sequenced using a 4017 counter clocked with a two-transistor oscillator. It was interesting - I tried a 7555 but it had some spikes in the output waveform (classsic CMOS totem-pole) that caused the counter to double-count. The transistor oscillator turned out to be a better solution.

I'll include a picture - does not show up too well.
It has a translucent nosecone with red and green led's inside.
It also a ring of red and green leds and three strobes pointing out the side.
Adds almost exactly 400gms to the weight.
 

FredA

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BTW - don't buy a camera and gut it.

If you friendly to your local photo processor, you can probably get all you want. I left with a shopping bag full of cameras when I asked.

These cameras are ripped open and the file cartrige (35mm) is removed for processing and the AA or AAA battery is removed to recycle. The rest just goes in the "recycle" bin with an unknown fate. I was able to get all I want just for asking - in fact, they save the Fuji versions for me since they are harder to find and have a smaller circuit board.
 

PunkRocketScience

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Great thread Silver!

I have been thinking about the same thing for a while, as I WORK in a photo lab and have hundreds of the silly single use cameras!

With these great ideas, I should be able to come up with a great strobe payload package!
 

Hospital_Rocket

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Ditto on what Fred commented...

You need at least 4.5V for an NE555 to function.
 

FredA

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Just be careful -- these things are tiny, but pack a wallup.

Always - everytime before you touch it - confirm that it is off and short the big capacitor with a screw driver or similar conductive device with an insulated handle. You need to remove any charge it is holding.

I wouldn't want anybody to get hurt.
 

Micromeister

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I found by closeing the circuit on one of these camera boards and soldering in a AAA battery holder the cap charges and fires at about a 2-3 second rate, perfect for night flights. However the filliments don't handle hard landings very well, a few led back-ups may help locate the model on the ground should the strobe fail.
 

FredA

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You really do need to change the main storage cap to a smaller size. Most of these units have 80uF to 120uF caps which is too much for repeated flashes. Downsize this to something in the 1uF to 10uf range to avoid overstressing the flash tube. Just make sure you choose a cap rated for over 300V. I use 3.3uF wih good results.

These little flash tubes are not made for repeated, full-power flashes. They get hot and fail easily (from mechanical shock).
 

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