An Inexpensive Flasher for Night Launches: take two. by Anthony Cooper, LUNAR #571 After reading Bill Orvis's article "An Inexpensive Flasher for Night Launches" in LUNAR 'clips Volume 4, Number 4 -- September, 1997 (It's off line now and you have to as Lynn Kissel for it.) I felt that I could contribute something useful. Bill Westfield also pointed out this page for the electronic hobbyist, Don Klipstein's Web Site!  There are some great information about lights, LEDs and xenon flash tubes.  At first I thought that I was very cleaver,  I went to Wal-Mart and bought the cheapest disposable camera they had. I was able to purchase the Jazz camera for $7+tax.

Discussing my great find with "Lee ?" at the 9-21-97 LUNAR launch, he told me how to get the cameras for free. Just ask the 1 hr developer for the empty shells. I now have a dozen shells with flashes. They are all assorted Kodak models. Lee mentioned how he like the small circuit board in the JAZZ which is barely 1" across. Now that I have disassembled two of the Kodak's, I know what he means. The  Kodaks are typically about 2" by 2" square. Inconvenient for fitting into a rocket body tube.

This is picture of the front of the circuit board from the Jazz.

I removed the flash and capacitor from the circuit board and oriented them along the longitudinal axis. The goal in mind is to create a flasher with as small of a diameter as possible. I then added a switch (Radio Shack #275-409).

Next I removed the battery clip and added a C cell. This doubled the weight to 2 oz but also gives me double the current and flash rate. I just soldered wires in the holes where I removed the clips from then epoxied the battery to the end of the circuit board.  The next picture is the schematic for the flash before I started.

I then wanted to trigger the flash. The neon bulb idea was clever but I wanted something else. I finally ended up with a SCR. I used the existing neon bulb to fire the SCR. The additional diode provides the biasing for the gate to fire the SCR. When the charge on the .022uf capacitor gets high enough to fire the neon bulb. The diode gets forward biased and drops .7v to fire the SCR. The disadvantage is the my flash rate was not as high as Bill's. I was getting about 1 flash / 10 seconds. The whole flight could be over in that time frame. Next I went to work on the flash rate. I had to get the recharge time down. Bigger batteries helped, but they also added weight. I compromised and used a C cell. It didn't add to the minimum diameter of the flasher. This only got me to about 1 flash / 8 seconds. Next thing to reduce the charge time is to shrink the size of the flash capacitor. I replaced the 160uf capacitor with a 10uf capacitor. This raised my flash rate to more than 1 flash / second.

This silk screen is correct. I have one working model now. The dimensions are 1" wide, .75" high, and 2.5" long without battery. It should fit inside a BT30 body tube. I'm thinking about the nose cone of a Phoenix missile. Some nose cones are transparent enough that the flash can be seen through the plastic. The phoenix is just such of an example. Be careful of T1. There are at lease two different pin outs.

This is another light circuit I made for flashing LEDs. Two pairs of LEDs blink alternately and the fifth LED flashes for 100mSec. I made it an ultra bright LED of 12000mcd (milli candela). It, unfortunately has a very narrow field of view. It has to be pointing with in 60 degrees of your eyes for you to see it.

One last circuit. I made this circuit to run lights up and down a Mean Machine. Again, if you print this page, all the details should come clear.