I need a simple strobe

[MillenniumFalsehood]

I'm trying to build a strobe effect for a Federation ship and I need a very simple circuit to make a bunch of LEDs strobe. I was going to use a transistor flip-flop circuit but the effect is too regular and I want a similar effect as the ones used in the movies without using PICs or pre-assembled kits; just normal everyday components you can buy from Radio Shack or pull from a circuit board.

Perhaps I could (theoretically) attach a capacitor to the FF circuit in such a way that it charges and releases it's energy into the LED to produce a flash.

[Sparky]

There are some simple circuits in the sticky, using a cap and some other parts to get a strobe effect, there's also the circuit for this antenna strobe:

http://www.kc6sye.com/techmages_11_8_06.html

http://www.kc6sye.com/techmages_11_10_06.html

[jwrjr]

The easiest way is to use a PIC, but you said that you don't want to do that. The next easiest way is to use a type '555' chip, which Radio Shack carries at some stores. You just have to choose the resistors correctly.

[MillenniumFalsehood]

I do have a bunch of 555s lying around. I'll try them.

[Styrofoam_Guy]

Try and find a flashing LED and wire that in series with the other LEDS so when the flahing LED blinks the other LEDs will also.

Of course you do not have control over the flash rate besides what the LED flashes at.

You could also purchase a commercial kit
http://store.qkits.com/moreinfo.cfm/FK141

http://www.fiberopticproducts.com/danis ... ry=Flshadj

http://www.fiberopticproducts.com/danis ... y=Flashers

[jwrjr]

If you are going to use a 555, do you want help calculating the resistor and capacitor values? (There is a trick to it that they don't tell in the data sheets.)

[SpaceDuck]

If you are going to use a 555, do you want help calculating the resistor and capacitor values? (There is a trick to it that they don't tell in the data sheets.)

If "Millenium" doesn't, I do!

[MillenniumFalsehood]

Any help would be appreciated!

Btw, I got both the LED flasher mini-circuit and flashing red LED both from my local Radio Shack and they both flash at different rates. I'll review ST3 and see which lights flashon my ship(Oberth class starship)

[jwrjr]

Trying to describe this with a minimum of math is a bit tricky, but I'll try. Ra is the resistor between the supply voltage and pin 7 (I think. I'm doing this from memory). Rb is the resistor between pin 7 and pin 6. C is the capacitor between pin 6 and ground. To get the right timing for a strobe, choose C to be 10 uf. Then Ra = 80k ohms. Use a series combination of 33k and 47k. Rb is then 12k. Use a series combination of 10k and 2.2k. You can get precision resistors nearly the right value if you have access to a place that sells precision resistors.
This will give you the right length pulse (about 83 ms) at the right frequency (about 1/sec). This pulse is active when the output goes to ground. so connect the led+resistor between the positive supply voltage and the output. If you want to control several strobes (the Refit has 4), use a PNP transistor or (preferably) a p-channel power mosfet.

[MillenniumFalsehood]

When you say "Right pulse. . .at the right frequency" do you mean right pulse for a Federation starship or the right pulse for functionality of the circuit?

[jwrjr]

The Refit and the NX-01 both use an 83 ms pulse occurring once per second for the strobe. That much I know for sure.

[Scott Hasty]

MF, I have a circuit that makes a great strobe pulse utilizing the 555 (actually the 556 which is 2 555's in one package). I can shoot it to you if you want.

Scottie