In fact, when you throw away a single-use camera, if there is a flash unit you also throw it.
That's regrettable because this part is still in order of use and is rarely recycled.
There is the flash unit in itself and a battery, and this battery is full in most cases as we don't use the flash for each photo taken.
So let's do something nice and (re-)useful.
Step 1: Gather Material
-1- old single-use cameras, the more is the best.
you can have this for free in most Photographer's Shop, you just have to ask them. That's what I do: Monday "hello can you keep those cameras for me" and a week later I have a full box of them.
-5- a power supply for your relays
-6- your usual tools.
and that's almost all.
Step 2: Open It
Here it's a duo of copper strips.
You just have to establish the contact between those strips to ignite the flash.
The trigger may be a contact between the ground of the flash unit and a pole in the circuit.
Sold long wires on the trigger.
Step 3: Close It and Repeat Operation 2 and 3
Check if there's a flash when you put in contact the wires.
Repeat operation 2 and 3 to build as flash-units as you want.
Step 4: Command System
That's what we do now:
We build a multi vibrator that will drive flash units by making the contact between the wires automatically.
This trigger system is compound of two parts:
1st one The multi vibrator that generates impulsions
2nd one A series of relays that duplicate the signal for each flash unit.
At each impulsion, the relays do the contact between the two wires that activate the
Follow these simple schematics.
Do as many multi vibrator and/or relays as you need
Connect the flash wires to the poles A and B.
You also have to power up the relays according to their specifications.
Step 5: Bonus
Step 6: Light It On
This does a great effect; a bit like photographers along a red carpet.
I hope you will enjoy this green project recycling old disposable cameras.
ps: Excuse me if I made some mistakes, but English is not my mother thong.