Intro: Lightning Effect Using Camera Flash Units
Make an electronic circuit that will trigger camera flashes in sync with a thunder soundtrack (great for Halloween)! The camera flashes are salvaged from old, broken cameras. When used along with lamps plugged into a color organ circuit, it makes a very effective lightning effect.
Here are two videos of the display in operation. In the outdoor view, the camera flashes are visible but the video camera does not pick up the color organ lamps flashing. The second video (inside the house) shows a lamp connected to the color organ flickering in sync with the soundtrack.
Step 1: Safety Warning! Electrical Shock Hazard!
Before I start anything, I have to warn that a camera flash unit uses HIGH VOLTAGE (300V or more) that is stored in a large capacitor. A LETHAL charge can be stored in the capacitor even if the camera has not been used for a long time!!! Use EXTREME CAUTION when disassembling any camera that has a flash unit.
- NEVER TOUCH THE CAPACITOR LEADS OR THE LEADS OF THE FLASH BULB.
- The high voltage is also present at certain points on the flash control circuit of the camera.
- If you are not experienced with electronics work, DO NOT ATTEMPT to disassemble a flash camera.
- If you are uneasy about handling high voltage electronics, you can use standalone flash units with this instructable. You will not need to disassemble the flash unit.
Step 2: What You Need
Camera flash units . These can be salvaged from old, broken cameras, or they can be standalone flash units. The circuit I built can drive 4 flash units. I used 3 flash units extracted from broken cameras, plus one standalone flash unit which needed no modification. The standalone flash unit approach is recommended for those with limited electronics experience, or for those who are not willing to risk a deadly shock from a camera flash capacitor.
Power supplies to run the flash units (batteries will not last long if you try to power the flash units that way) and the electronic circuit. A power supply must provide at least 1.5 amps of current to power a flash. Some large wall plug AC adapters will work if they are rated at least 1 amp (the charging is intermittent so the 1.5 amp peak current should not overheat the adapter).
Electronic parts . See the circuit diagram in the next step for the parts you need. The key parts are relays, op amps, a 555 timer, and a transistor.
A 'color organ' circuit. These are available in kit form or pre-built on the internet, and circuits are also available on the internet if you want to build from scratch. You want one that can drive at least 60W lights.
Lots of wire and extension cords , if you are going to have the display operating in more than one room. In my case I had it running in 4 rooms so there were wires all over the house. 24 gauge speaker wire (the thin stuff you get at the dollar store) works fine. Lucky for me, the central vac installer left a big spool of wire behind so I used some of that.
A stereo. You need a pretty powerful one and big speakers to make a good effect outdoors.
A thunder soundtrack. I downloaded several thunder .mp3 files from the internet and wrote them to a CD which I played with "repeat" so it ran over and over all evening. The files I used are attached for your convenience.
Step 3: The Circuit
Click the little "i" symbol in the top left of the picture to see the schematic more clearly.
The terminals "In +" and "In -" are connected to the speaker wires from your stereo. D1 protects the circuit from overvoltages if you turn your stereo volume too high.
The relays I used are 5V DPDT, so each one can trigger two flashes. I used two of them to trigger 4 flashes. My circuit is powered with 5V because my relays were 5V, but if you have 12V relays this circuit can be powered by 12V also.
The 2N2222A transistor needs a small heat sink to handle the relay coil currents.
The LM324 (U1) is an op amp that can be run from a single power supply. Other op amps may not work in this circuit.
The first part of the circuit, C1 and R1, is a high-pass filter. This is because we want the circuit to respond to the initial high-pitched 'crack' sound of the lightning, not the following rumble. The next part (D2, C2, R6) is a peak detect circuit, which generates an output pulse when the voltage level exceeds a certain threshold. The 'certain threshold' is also connected to a peak detect circuit but with a very slow decay time (D3, C3, R4), so that it automatically adjusts to the level of the last thunderclap. The LED helps when adjusting the circuit, so you can tell when the peak detect circuit is triggering. Adjust R5 so that the circuit triggers at the start of each thunderclap.
The output of the peak detect circuit triggers a 555 timer (U2), which generates a 20 ms pulse for the flash relays. The circuit portion around U1B prevents the 555 from re-triggering for about 5 seconds, this allows the flashes time to recharge..
Q1 is used to drive the relays, because the 555 does not have enough output current on its own. The schematic shows 4 SPDT (single pole, double throw) relays, because the schematic program did not have DPDT (double pole, double throw) relays, but I actually only had two DPDT relays in the circuit.. The relays I used were some scrap parts from work, I don't know the part number, but something like Omron G5V-2-DC5 would work. D6 is important, to protect Q1 from overvoltages when the relays are switched off.
Step 4: Circuit Construction
I assembled the circuit on a breadboard. This made it very easy to make changes. Once I was finished, I didn't bother transfering the circuit to a soldered circuit board, I just put the whole works into a project case to protect it from curious fingers. The project case was re-used from a previous project, so pay no attention to the unused connectors. To save time I just passed the wires through the ventilation holes in the case and tied them in place, except for the power wires which I connected to the banana jacks already on the case.
I powered it with a +5V regulated bench power supply.
I also built a 3V voltage regulator circuit using a 317T voltage regulator (see Fig. 5 in the data sheet for this circuit) to power a 110 camera flash (originally powered by two AA batteries). The voltage regulator needed a big heat sink to handle the current drawn by the flash.
The photos are uploaded with full resolution so you can zoom in to view details if you like (click the "i" in the upper left).
Step 5: Camera Disassembly
So, you're feeling like a daredevil, willing to risk electrocution and take apart a camera?
OK, just remove every screw you can find, until the camera looks exactly like the picture. DO NOT TOUCH any of the electrical connections of the flash bulb, the flash capacitor, or the flash circuit. There can be HIGH VOLTAGE stored in the flash capacitor even if the camera has not been used for a while, and this high voltage is present on the flash bulb terminals and certain points on the flash circuit board also.
Identifying the flash components in a camera is really not that difficult. The flash bulb itself is obvious. Connected to the flash bulb with wires will be a large capacitor, usually cylinder shaped with writing on it such as "150 uF 350V". Also connected to the flash bulb and/or the capacitor will be the flash circuit board. The flash circuit is usually located on a separate circuit board from all the other electronics, and for good reason since there is high voltage (300V or more) in the flash circuit.
Before you cut any of the wires connecting the flash circuit board to the rest of the camera, identify the power supply wires. Usually they are red (+) and black (-). Check with a multimeter that these wires connect to the battery terminals of the camera. Often the + wire does not connect directly to the + battery terminal, but is switched on somewhere else in the camera.
You can now cut all the wires between the camera and the flash circuit and remove the flash unit from the camera. The next job is to identify the rest of the wires leading to the flash unit. One of these wires will be an "enable" signal, to turn on the flash circuit and charge the capacitor, preparing for a flash photo. Another wire will be the "flash" signal which triggers the flash. You can just experiment to see what each wire does. Apply power to the power supply wires (same voltage as the original batteries in the camera, for example if the camera uses 4 AA batteries, power the flash circuit with 6V). Connect a multimeter to the flash capacitor so you can tell when it is charging. Connect one of the extra wires briefly to ground or power, and watch the multimeter for signs of charging. Once you find the wire that enables the charging, search for the wire that triggers the flash.
There is some risk of blowing up something and frying the flash circuit, but what the heck, you didn't pay for that camera, did you?? For example, in one camera I took apart, there were more wires than what I identified above, and I never did figure them all out, and in the process of experimenting something fried in the circuit so that it was always charging. This was a fancy circuit that monitored the capacitor voltage and shut off the charging circuit when the capacitor voltage reached the appropriate level; if the charging circuit was allowed to continue (which it did in it's fried state), the capacitor voltage built up to well above the maximum voltage printed on the capacitor. I solved that problem by using a 3V supply voltage instead of the 6V battery voltage of the original camera, so that the capacitor voltage saturated below its maximum.
The easiest cameras to get flash units from are the simplest ones, such as single-use cameras, old 110 pocket cameras, and other simple cameras with no LCD displays or other electronic features. These ones will have a very simple flash circuit with obvious power connections to the batteries and a mechanical switch which is part of the shutter mechanism to fire the flash.
Step 6: Package the Flash Units
Once you have the flash unit working, put it in a plastic package so it can be used safely. I used margarine and cottage cheese containers, they are easy to get and easy to work with. Cut a hole in the bottom of the container (use a knife or scissors) and tape the flash bulb inside the hole. Tape the rest of the components inside the container. Cut a small hole to bring the wires outside the container. You will have two power wires (+ and -) and two flash trigger wires. Make sure you know which wire is which! For my 110 camera, I re-packaged the flash back into the camera, using the original camera body as the package for the flash (see intro photo).
Step 7: Using Standalone Camera Flash Units
For one of my flashes, I used a standalone camera flash unit. These are powered by batteries, and are triggered by shorting the two contacts on the 'hot shoe' mount. For use with this display, you will have to power the flash unit using a power supply, unless you want to be changing batteries every few minutes. Some flash units have an external power jack, but most don't. I used some alligator clips to connect a 5V power supply to the battery terminals. The flash normally works on 6V (4 AA batteries) but worked fine on 5V.
The wires connected to the 'hot shoe' mount will be connected to the normally-open contacts of one of the relays. When the relay actuates, it will short the wires together and trigger the flash.
Step 8: The Color Organ
I was lucky enough to find this homemade color organ circuit at a yard sale. You can find kits on the internet, for example here , or pre-made circuits. For safety, be sure to properly package the circuit and include a fuse.
The camera flashes on their own are not very spectacular as a lightning effect, and the color organ alone is also kind of boring, but the combination is very effective. The camera flash goes off at the beginning of the thunderclap, followed by the flickering lamps as the rolling thunder sound continues.
Plug 3 extension cords into the color organ, and run them to lamps around the house. I had 4 lamps in 4 rooms, so I plugged 2 of the lamps into one channel of the color organ (be careful not to exceed the wattage rating of the color organ circuit).