Search for the Holy Grail

A "strobe light" is a device that emits regularly timed flashes of light. A "black light" emits an invisible form of light that causes certain inks, dyes, paint, and other materials to glow. It is natural to wish to combine these two interesting lighting effects. The result is a black light strobe.

Every once in a while, the topic of black light strobes comes up in the Halloween e-mail list. There have been a few mentions of commercial black light strobes, which have traditionally been quite expensive. There has been speculation about various ways in which a black light strobe might be built.

• Original cheap strobing black light
• Second-generation cheap strobing black light
• Flourostrobe - Nice expensive strobing black light
• LED-Based Black Light Strobe
• Sources
• Build your own

The unit looks like an ordinary fluorescent black light fixture, except that the black plastic base is thicker than the ones you normally see. It contains a genuine GE 15W bulb (F15T8-BLB). It has a flat reflector that seems to be made out of a thin sheet of chromed mylar. It has a 2-prong AC cord with a polarized safety plug. There is a starter mounted in a hole in the back. The starter in mine had a plastic shell; the one in the store was metal. In the long side of the fixture, there is an indentation with an on/off switch and a knob to control flash rate. A sign on the side of the box says that the flash rate can go up to 20 cycles per second.

The box says "Lumaseries", "made in the USA", and "Distributed by Spencer Gifts, Inc." The stock number is 415612. The sticker on the back of the fixture says "strobing fluorescent model 675" and "Data Display Systems, Philadelphia, PA". The little slip of paper in the box says "Decora Industries, Inc."

The sticker claims that these units go for $35. When introduced, they were on sale for $30 (seemingly as a new item introduction). Your Spencer Wild And Crazy Card will knock a few dollars off of that.

Note that the 3-month warranty does not cover the bulb. This might be normal for such a fragile and easily-reached component. Or it could be that the bulb life for this device is expected to be short. If they built this thing the way I suspect that they did - by keeping the starter filaments hot all of the time - one would expect shorter than normal bulb life. But it's worth it for the effect!

So, does it work?

Yes. Mostly.

The unit works just like a conventional fluorescent black light, except that it flickers on and off. An ordinary black light twists your mind one way; an ordinary strobe twists it another. This twists your mind until it snaps into little bitty pieces that fall all over the carpet. The effect is so unusual, it might make you lose your lunch.

Since a fluorescent blub is used, the light that is produced is of good "black light" quality and quantity.

Note, though, that the flashes from this unit aren't all that strobe-like. A xenon strobe produces a very fast, "crisp" flash of light. This thing has relatively long on periods. Think of it as a lamp that just has the power switch flipped on and off automatically. A friend of mine compared it to the flickering of a defective fluorescent lamp.

An analysis of the circuit shows why this unit has relatively long "on" times. When dealing with a conventional fluorescent lamp, the normal mode of operation is that each end of the lamp be warmed up with "starter filaments". Once the lamp is warm, it is easily brought to full illumination. You can see this for yourself when you start up a normal white fluorescent lamp: for a second or so, the ends of the lamp tube glow orange, before the lamp kicks into life. If the filaments were kept warm at all times, there would be no problem turning the lamp on and off as fast as one might want. But the design of this strobe doesn't do that. It has no mechanism for continuously heating the starter filaments. Instead, it tries to keep the lamp hot by not leaving it turned off for long. Thus the duty cycle is intentionally kept long, in order to keep the lamp hot so that the starter filaments do not need to be used.

The unit contains a genuine GE 15W bulb (F15T8-BLB). The box proudly proclaims "hyperbolic reflector". This means that the top surface of the case, under the lamp, is molded into a curve, and covered with shiny foil. The fixture is very light. Power is provided by a heavy wall wart that contains the ballast.

Performance is very like the original inexpensive unit. So is the internal design.

  ETA Systems makes a high-output blacklight strobe that uses the 40watt 
  F40BLB lamp. 1532 Enterprise Pkwy. Twinsbuerg, OH 44087 | 
  216-425-3388 | eta@etasys.com | www.etasys.com

  I've seen it- neat product, output appears brighter than a regular BLB 
  fixture, price was a bit steep as I recall, but I don't recall how much it 
  was.

  We sell Black Light Strobes called Flourostrobes and they ARE AWSOME!  
  It is 4foot long with variable speed control with monting brackets.

  They cost about $460.00 each...and well worth every penny.  They can 
  make blacking light painting appear and disappear which is an awsome 
  effect which we use in our haunted house.

  Check out our new website...which is only about 75% complete we list 
  them on the site.
  http://www.halloweenproductions.com

• Spencer Gifts #415612 - Black Light Strobe - $35

  Assembled and tested, in enclosure - just plug it in and go. Has adjustable flash rate.

  I bought one of these. The combination of the black light and strobe effect is unique and well worth considering in your haunt.

  Note, though, that the flashes from this unit aren't all that strobe-like. A xenon strobe produces a very fast, "crisp" flash of light. This thing simply turns on and off. A friend of mine compared it to a defective fluorescent lamp, flickering on and off. Some people think this detracts from the effect and mutter about buying high-end equopment for >$400 instead. Better try it out in the store and see what you think.

Thank you for visiting. Your comments are welcome.
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