Studio Lighting - DIY: Home-made Power Pack Flashes (Part II) - Variations on a theme
Ok, So you've got your DIY Flash/Strobe working. Now you want to evolve to a full DIY studio - Here are some uses for the flash unit (again, courtesy of Avner Richard). In this article you will find some creative ueses for the basic circuit - Multipe flahs heads and controling output power - as well as some basic studio flash setups - beauty dish, spot light, soft box, ring light and more.
Remember, you are working with high voltage, so please, please (please!!!) read the Dealing With High Voltage warning
Here are ideas for enhancing your home made flash - you can have a peek at Avner's model gallery to see the results of the ideas combined. If you need Flashtubes, Xenon Flash Tubes or other parts contact Avner via www.photoar.com
Multiple flash heads
OK, so we were explaining the principles of single flash circuitry, but the interesting part of this project is the possibility to power several flash heads with a single power unit (power pack).
Actually, the circuit remains almost exactly the same. The only chage - you are about to add storage capacitors, and more flash tubes, of course.
This extended setup will allow you to use different flash tubes, of different models, without having interface issues between them.
You can also have different power ratings – for example: one flash tube firing only 50W/s and another firing 200W/s, all synchronized, keeping the same basic circuit layout.
Looking back at the original basic schematic, you’ll find the storage capacitor (C-store). Here we will be adding more storage capacitors, for each of the flash tubes.
Pay attention to the additional diodes, between the POSITIVE power line and the + terminal of each of the capacitors.
The diodes will insulate each capacitor from the others, to allow a capacitor bank array of different power storage amounts. That way, a “channel” designed to power a flash tube of 50W/s, using a 1000uF capacitor, will NOT receive more power from the other capacitors (which can overpower the tube). Each channel is individual, with its capacitors and its tubes. The common between them is the charging system, of course, that will feed all capacitors in the same time.
Regarding the triggering system, you will have to create extended cables for each flash head. Using a tri-wire cable, you can set up the flash head away from the power unit. The cable will have: one positive wire (directly from capacitor’s +); one negative wire (directly from capacitor’s -), and one trigger wire.
You will have to take the trigger transformer out of the main circuit, and attach it to the flash tube, one leg to the negative wire, one leg to the trigger plate of the tube, and the third wire, coming from the SCR will be the “trigger wire” in the cable above. This way, the trigger pulse that will come out of the main unit to the flash heads will be of 250V only. Then it will become several KV’s in the flash head, directly to the tube; so we won’t have some 10,000 volts pulse traveling around our cable.
For several flash heads, we will solder a trigger transformer to every flash tube, as described above, and connecting all cables’ trigger wires to the output of the SCR at the main unit.
Variable power intensity
Another feature available on commercial strobes is the option to control the flash power manually using a knob.
You can use the same method explained for multiple channel flash heads, with one flash tube only.
Using a rotary switch, you can choose the desired capacitor value for a specific flash tube. Let’s refer to the following diagram-
For example – C1 is 1,000uF, C2 is 2,000uF, C3 is 4,000uF, C4 is 8,000uF and C5 is 16,000uF. This way, using the 5-way rotary switch you can choose a flash power of 50, 100, 200, 400 or 800 W/s.
Make sure you choose a heavy duty rotary switch that supports ~300v with highest current rating you can find. Yes, this way is not very efficient if we talk about “capacitors waste” – every time only one capacitor is used, the others are disconnected. But this is the best and simplest way to control the intensity of the flash. Further ways are dealing with complicated electronic controllers.
You will find the diodes here as well, they keep the capacitors isolated from the eachother. It allows the flash tube to drain power ONLY from the selected capacitors. The other capacitors are waiting charged until they will be selected.
This schematic is relevant for ONE flash head channel only.
You can build on this idea and make a complex project - an array of several channels, each channel having an array of capacitors with a rotary switch to select the power.
And here are some ideas for different flash heads
Mounted on a lighting tripod, this head has a big softbox attached to it. The softbox is 60x60cm, and was self-built.
Consisted of 4 silver coated cardboard faces, and the front face is based on sketching paper, which is white translucent, will both diffuse the light, AND let it pass through.
Total cost: about 3$.
This one is made from a round reflector element. You can search home depot or lighting stores for this type of lamp, and hack it to match your needs with the flash tube inside. Here a round flash tube will be essential, to achieve the beauty dish’s lighting effect.
One of the most loved lighting, and most popular for studio and outdoor shooting of subject is ring light. Made of a large microwave plastic cover, which I hacked a hole (10cm dia.) in its center, and mounted some kind of ‘round wall’ around the hole.
Here I’ll recommend using at least 4 LINEAR flash tubes, located with regular spaces between them. You can also use MORE tubes of LOWER power (example: 10 tubes of 60W/s to achieve 600W/s). tubes should be connected in parallel, and must be of the same model and type.
Spot light (AKA Hair Light)
This light is concentrated. It is used to create light spots on the background, it can also be used as hair lamp from above (this is why it is called hair light).
Very simple - this flash tube has been mounted inside a thick carton tube.
You can also use some reflective materials at the tube’s back to reflect all the light towards the tube’s exit. Be careful when using reflective materials, most of them will conduct electricity. They should be totally insulated from the flash tube’s terminals and stay untouchable.
Now, if you have gone this far, you are close to owning a full homemade studio. see the following articles to complete the setup: the DIY backdrop stand, the DIY muslin backdrop, The DIY reflector stand and a basic lighting diagram
This project is dealing with high voltage circuitry. Please be extremely careful and stick to the given schematics!
Charged capacitors can still have juice after hours, days, and even weeks; never touch capacitors terminals unless you are sure it is fully discharged.
Never work on a circuitry while it is connected to the mains power !!!
Never work on a circuitry while its capacitors are still charged. Be sure to discharge them fully.
Neither the writer nor the publisher of this article are responsible to any damage caused by attempts to reproduce this project. This project was made for 200V voltage, for other currents, adjustments have to be made.
You are the only responsible to your equipment and life. don't drink and weld.