How and Where to get Parts for Large Xenon Strobes

Contents:

• Powerful Flashtubes
• Big Capacitors

WARNING! Stuff discussed here can be dangerous. High voltages here can electrocute you. Quartz flashtubes (and a few specialty glass ones) emit shortwave and mediumwave UV. Nearly all flashtubes emit longwave UV. Large quantities of different types of UV can burn/damage different parts of your eyes and different layers of your skin. Shortwave and mediumwave UV may be hazardous in not-so-large quantities. For a greater discussion of xenon strobe hazards and safety, Go Here!

Powerful Flashtubes:

You can order this flashtube at some professional photo supply shops for approx. US$ 110 to 120. One such place is B&H Photo in New York City.
Phone: (800)-947-9954, (212)-444-6608
FAX: (800)-947-7008, (212)-239-7770
Web: http://www.bhphotovideo.com/
Please beware that B&H seems to take more holidays than usual, making them not always reachable.

Another source: Abbey Camera, http://www.abbeycamera.com. Phone: (215)-236-1200, (800)-252-2239 toll-free in the USA outside PA.

Price I saw recently in their catalog is $103.95.

Another source with a price around $99: Vantage Lighting.

This flashtube has a maximum rated flash energy of absolutely bigtime - 3200 watt-seconds. The flashtube works best at voltages slightly under a kilovolt. I would derate the quantity of energy proportionately with voltage below 900 volts, and not use this flashtube below 500 volts.

To make things easy on the flashtube's electrodes with heavily repeated flashing, I recommend a maximum amount of energy (in watt-seconds or joules) of 1,000 or 1.1111 times the voltage, whichever is lower.

As for minimum energy for efficient flashing - at least 100 watt-seconds, maybe 200.

As for maximum average power input to this flashtube? This tube can take a beating. In free air, it seems to handle up to 200 watts OK with a flash energy between 200 and 1,000 watt-seconds and voltages of 700 to 1100 volts. Use less average power with other voltages and other quantities of energy, or if the tube is enclosed in something where heat will accumulate. This tube can be forced-air-cooled for more power handling. Connect a small vacuum cleaner to it, and it can probably take 600 watts long-term and a kilowatt for half a minute.

As a brief torture test of this flashtube, I have given it an average power input of 700-800 watts for a couple minutes with no forced-air cooling (but otherwise with better-than-usual ventillation), and couldn't ruin it. I just can't smoke it, break it, nor burn it. However, really prolonged really heavy use is known to discolor the quartz tubing. Should you want to exceed my recommendations and be able to tolerate some gradual tubing discoloration or you don't need extraordinary life expectancy, GO FOR IT. This tube can take a beating.

One thing about the Speedotron 14570/MW8QV: It triggers unusually easily. I have been able to consistently trigger this tube with 3 and 4 KV pulses from cheap trigger transformers. Please note that these trigger transformers want primary voltages around 300 volts, less than the flashtube wants. To work a cheapie trigger transformer from higher voltages, feed the trigger capacitor from a voltage divider instead of a resistor. For example, use 1 meg from the capacitor's positive lead to the positive point of the energy storage capacitor, and a 470K resistor from the capacitor's positive lead to the negative point of the energy storage capacitor.

As for maximum voltage, I recommend against going much over a kilovolt. I have known this tube to self-fire at 1600 volts, and inconsistently do this or not do this. This impairs some use of this tube for short-flash and enhanced-UV applications. This also impairs attempts to efficiently use this tube at low flash energy but with really high voltage to get xenon ion spectrum output.

A lower voltage serious flashtube is the Photogenic C4-5. This is the flashtube for the Photogenic "Powerlight" 1500SL flash unit. There is a UV-coated/color corrected version of this flashtube. This flashtube is available with either clear or frosted glass domes with a small hole in the top of the dome. Be sure what you are getting.
This flashtube works best around 400-550 volts. The minimum voltage for reliable flashing is 360 volts. It takes up to at least 1,000 watt-seconds, and should take 500 repeatedly and have a good life expectancy. I would derate the flash energy proportionately with voltage below 450 volts. It can take a 150 watt average power input, 200 watts for 1 minute. Both these can be increased by at least 50 watts with some forced-air cooling. I would derate these figures proportionately with voltage below 500 volts.

Avoid using more than 500 volts unless you want plenty of UV and a slightly more-blue-than-average color. Also this tube draws really high peak current (greatly exceeding a kilo-amp) at these voltages and can heat up capacitors that don't have really low resistance.

This tube needs more trigger voltage than the Speedotron one - I recommend 6 KV trigger pulses. It usually triggers at 3 KV, but I have found triggering below around 5 KV to not always be reliable.

This flashtube is also available at B&H, but costs a bit more than the Speedotron one - approx. US$ 134.

A smaller, truly compact but serious quartz xenon flashtube is the Lumedyne 090Q. It has a rating of 2400 W-S which I consider unrealistically optimistic. I believe it can take 1200 W-S occaisionally and 400 W-S heavily repeated with reasonable life expectancy. As for average input power, I don't yet know but think it can take 100 watts short term and 50 watts long term. I believe the voltage should be 500 to 700 volts.
This tube costs approx. $130. I recommend it only where the compact size of this tube is necessary. Otherwise, I recommend the Speedotron MW8QV / 14570 instead.

I have some technical info on some specific flashtubes in my Flashtube Ratings/Data Page.

FOR A LESS SERIOUS LARGER FLASHTUBE:

There is the "FT6", available at some pro photo supply stores. This is a glass tube, not a quartz one. Maximum rated average power input is 100 watts for 1 minute, 50 watts long-term with good ventillation. Sorry, that's *with* forced air cooling! (I looked at the box 1/7/99) The maximum rated energy is 500 watt-seconds.

There is a maximum voltage rating of 500 volts. I have found the xenon pressure in this tube to be a bit on the low side, but I don't really agree with this voltage rating. (CAUTION - Exceed 500 volts only at your own risk.) I seem to think lower voltages are recommended to get reduced UV and a lower color temperature closer to 5500 degrees K. as opposed to closer to 6000 degrees K that xenon strobes often give. I have successfully flashed this tube with 750 volts and 750 watt-seconds, so I believe 600 volts should generally be safe. Tripled 120VAC should be OK. I seem to think the minimum voltage for this flashtube is 300 volts, and energy and power ratings may be decreased proportionately with voltage below 400 volts.

The FT6 costs approx. US$ 70. I seem to think it is better to put out some more money and get a quartz flashtube like the Speedotron 14570/MW8QV.

UPDATE 1/7/98 - I just got a bit disappointed with some results using the Norman Enterprises FT-6. Flashing twice a second using 160 microfarads at 320 volts - only 8 joules and an average input power of only 16 watts - caused noticeable discoloration in the cathode end of the tubing after only about 10 hours. I no longer recommend this flashtube, especially not for any application not specifically endorsed by its manufacturer.

AN EVEN BIGGER OPTION FOR REPEATING STROBES!

One way to get one: Find a copier with a flashtube you like. Note its manufacturer and model number. Go to a place that sells replacement parts for that copier, and order a replacement flashtube. Then, go to my Xenon Strobe Design Guideline Page to determine appropriate energy and voltage. Straight flashtubes generally do well with really high voltages that give good efficiency at lower quantities of flash energy - good for faster-flashing strobes.

Another way: The EG&G Heimann division JG7905 is one I know about. It is about 57 cm. long, has an arc length of nearly 50 cm, and is 1 cm. in diameter. EG&G says 1500 volts minimum, 2100 volts nominal, and 2200 volts maximum, 200 watt-seconds (that's 90 uF at 2.1 KV), 1.3 flashes per second, with a life expectancy of 10 million flashes. I expect it can take up to 2500 volts with no trouble, flash energy up to 800 watt-seconds with a decent life expectancy (if derated proportionately with voltage below 2 KV), and at least 500 watts average power input with some forced air cooling (derate proportionately with voltage below 2 KV).

I have found this flashtube to sometimes not flash reliably below 1600 volts.

With energy in the 100 to 200 watt-second range, you would probably do well with outrageous voltages around 3 or 4 KV if you have capacitors conductive enough. Exceed EG&G's ratings only at your own risk. I have triggered this flashtube reliably with 6 KV trigger pulses. Wind two coils of very thin wire around the tube, in opposite directions, with turns about 1 to 1.5 cm. apart. Do not let any trigger wire get within about 1.5 to 2 cm. of the ends of the tube. Glue the ends of the trigger wires onto the tubing surface with very small blobs of silicone rubber. Your mileage may vary as to what it takes to trigger this thing. EG&G seems to think of a different trigger method than the usual one for strobes.

Someone gave this tube to me. I do not know prices, minimum orders, nor who can sell this tube to you. EG&G Heimann Division has a USA office with a phone number of (215)-368-0700.

Big Capacitors

For a slightly smaller size but costing more, there are the Mallory CGH and CGS series capacitors.

UPDATE 2/11/2001 - All Electronics (800-826-5432, 818-904-0524, http://www.allelectronics.com) has 2400 uF 450 volt "computer grade" electrolytic capacitors. The catalog number is CG-2445 and the price according to the 101 early 2001 catalog is $6.50 plus shipping.

Hosfelt Electronics (800-524-6464, 740-264-6464, http://www.hosfelt.com) sells a 2900 uF 400V "computer grade" capacitor, catalog number 15-981, for $14.95 according to their 98-C fall 1998 catalog.

Please note that the above electrolytic capacitors generally do well only with flash durations at least half a millisecond, preferably a millisecond. For shorter flashes likely with repeating strobes, I recommend laser energy storage capacitors or a bank of AC-rated motor run capacitors.

Easy ways to get 400 volts with fluorescent lamp ballasts.

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