LED Flashers - Uses?

If you paid more than $1-2 each, they are available online at great prices at

I've used them for night launches before. They are visible in an Estes Alpha III with clear (aquarium tubing) payload section attached. I first found them at a Spencer Gifts store, at $3.99 each. They are great bright little beggars, aren't they!

PA Tom NAR #76754

Mark, Red LED's require less voltage to run than blue. So as the battery voltage lowers the blue cuts out first.

Now to build something with a MCP430 processor. Hmmmm.

I checked out the link. The ones like mine are $1.99 each, but random color quantities of 144 are a great deal at $129. I paid $144 shipped for 100 red/blue combos. Thanks for the tip.

Mark Simpson NAR 71503 Level II God Bless our peacekeepers

I would have to see them. How heavy how larger etc..

blue led's take more "power" and therfore drain the batteries faster. Much faster.

blue you will note is probably brighter too.

Not quite. If they are on the same battery (alternating red/blue?) in parallel, then the blue will die first because it needs a higher voltage. If they are on separate batteries, and adjusted for similar brightness, the blue requires more current than the red and will drain the battery first.

-John DeMar

Chris Taylor Jr wrote:

is that not I just said ? it needs more power.

Thanks Robert, I thought that might have been the case.

Mark Simpson NAR 71503 Level II God Bless our peacekeepers

snipped-for-privacy@aol.com (RayDunakin) wrote in news: snipped-for-privacy@mb-m25.aol.com:

This is of course because blue light has a higher frequency, and since the vibrations are closer together, it is denser, and therefore for the same brightness, it is heavier than red light, which is why the blue elf gets tired faster.

len.

kaplow snipped-for-privacy@encompasserve.org.TRABoD (Bob Kaplow) wrote in news:+SjGW+AQq98$@eisner.encompasserve.org:

The bright-white LEDS are blue LEDS with a yellow phosphor over the die to give a white light. Both blue and white LEDS have a higher forward voltage drop,about 3.6 to 4.0V,and use about 20 ma. Red LEDs V drop is around 2.3V,IIRC,about the same current. It really depends on the individual LED specs.

So the blue LEDs perhaps draw more current as well?

Same sorts of current. More power. (P = IV) The internal circuits of the flasher modules may have other ideas, of course. I don't see any current limitting resistors, so that's gotta be on the chip somewhere.

You can use the little magnets that come with these to attach them to bigger batteries, but I don't think I'd trust that through a launch. I ran a 5-LED RED/BLUE "Star" chaser for 48 hours off a scavanged Li-Ion cell before the blue gave out. (if you got 24 hours blue, you did real well!)

They're depressing form an EE hobbyist point of view. For the sname price I can order a single bright blue LED from an electronics supplier, or one of these "jewelery items" with a couple bright LEDs. And a chip. And batteries. And a couple strong magnets. Sigh.

BillW

Ya, that one. Took a seminar on them and they gave us this neat little board. This will work great for altimeters.

FWIW,

You can use a flashing LED to make a string of regular LED's flash. Connect them, of course, in series. You can make one of those Radio Shark buzzers pulse intermittently by the same method.

Regards,

-Larry C.

Hi, Bill,

My take is that the PIC's do have a little better drive, but only marginally. They do a lot of "specmanship" games and publish numbers that are a little misleading. For example, while one pin may sink 25mA, an entire

Also, look at the Vol spec for the rated sink level. In many cases it's well above the common spec of 0.4V (logic 0 output). Some manufacturers won't go back and add sink specs for higher Vol levels - they don't want to rewrite and requal their test software nor increase test time.

Also, some manufacturers are almost anally conservative. 6-sigma quality progams tend to turn

Mostly, it's cost. While us old guys are used to high sink currents on ordinary parts - eg, 64mA sink per pin on 74F244 buffers - today's modern geometries mean that those 25mA drivers take up huge gobs of Silicon area compared to all the logic and memory substantially increasing die cost.

My 2 cents. YMMV.

Doug

Have you never seen a person concerned because their rocket was sitting on the pad for 1/2hour running off a 9V battery? An altimeter should run for days off a 9V battery and there should be no concern, but people are concerned.

Yeah, well. I've noticed that Electical "common sense" is a lot rarer than I thought it would be, even amoung nominally technical people. But I think this concern has more to do with the "xyz ignitors will fire reasonably reliably with a FRESH 9V battery" - how the 9V battery will behave when asked to fire the ignitor after some duration of "low" current drain is a more complicated question, and people worry even with their "ABC" ignitors and battery technologies that really ought not care nearly as much as a "transistor" 9V primary battery.

Maybe its time for a new generation of altimeters.

You already did that, didn't you? I think it's PAST time for a new generation of parachute deployment methods. Unfortunately, that's also a harder problem than making an altimeter that runs for days...

Hey, did you see the guy who charged a camera strobe from a calculator solar cell? Now THERE's a way to conserve your power but deliver a substantial burst of energy when the time comes!

Yes.

I suspect it would not be damaged from a BD charge that was exposed through a small hole like a delay transfer hole. Imminently practical if you ask me. Pratt Product! Invisioneered by Jerry Irvine. How ironic :)

Jerry

actually I would say it was invisioneered by Ray Dunakin since your post is replying to his inquiries about its practicality :-)

hehehe

substantial

I wonder, would a small camera strobe produce enough heat it ignite an ejection charge, Thermalite fuse, etc? If so, I wonder if there'd be some way to protect the strobe from damage so that it could be reused for multiple flights?

I don't believe that the strobe tube itself gets got enough to ignite anything, but the device stores enough energy to turn ordinary resistors and such into reasonable ignitors (perhaps not for rocket motors, without additional pyrogen.) There are assorted plans in the pyrotechnic hobby world for turning old disposable cameras into a "CD firing box" of the sort that will fire (simultaneously) a couple dozen ematches at the other end of a couple hundred feet of 22 gauge wire. (of course, ematches are the sorts of overly sensitive electrical firing devices that I think we need to get rid of...)

My point was that there are plenty of ways of increasing the "firing capacity" of an electrical circuit to the point where no one should have to worry about "use a fresh battery for every launch and worry if your electronics sit on the pad for long enough to interfere with that 'fresh' state." The mass penalty can be a bit high for small rockets, but if you're already using a 9V battery, you're not in that catagory. (ie it's not hard to build a circuit that will provide 5V@smallcurrent for your electronics proper, plus high currrent pulses for ignitors/etc, and still have it weigh less (including its own battery, of course) than a standard 9V alkaline battery.)

BillW

I hope the concern mostly arrises out of not knowing the altimeter and cautioning on the side of safety.

I do have a new generation of altimeters, and they work very well. But I am waiting to deploy them.

I had a design to use solar for an altimeter, as a backup source. Problem was it was only good for one rocket since it was built into the airframe. Secondly, I could find no reason to use it since a fresh 9V battery will run my altimeter longer than the range is open.

RDH8