I'm looking for a self contained slow flashing bright 5mm LED. 50% duty cycle ones are common, but I'd like something like one flash per 10 - or more - seconds, to cut down power consumption. No space in the housing to add electronics, so it has to be an all in one. 12 volts, obviously.
Slow flashing bright LED
Aug 23, 2005
13 Replies
Obviously?
Diodes dont come in volts!
They are valves if you prefer. You need a resistor in line or they are just a short. Different voltages need different resistors.
Granny, here's this egg. Now breathe out, and...
You can get LEDs with the appropriate resistor built in for 12v use. And obviously Dave isn't talking about plain LEDs, since he's asking for one with a flashing circuit built in - you don't think a simple diode will flash on its own, do you?
cheers, clive
Nope I have some here. They are nasty cheap ones but still flash, but no resister built in, you would need a 1k or thereabout.
You mean he wants a whole circuit built in! They make those? Cant see them in RS catalogue cd.
228-6032 228-6060 228-6076
et al.
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Unfortunately only with a 50% duty cycle, which is not what Dave wants.
cheers, clive
Not to you since you're a prick.
Sigh. I'm *perfectly* aware of basic LEDs being current driven.
However, there are flashing types that look just the same but have an internal IC - and these don't need a current limiting resistor for a wide range of volts.
I don't.
In both directions? Some valve.
The voltage is only one thing. You calculate the resistor value according to the forward current needed to drive it to the brightness you need (within limits) and the forward voltage drop.
The formula is Rs=(Vs-Vf)If
Dave has forgotten more than you'll ever know about electronics.
(c:
Douglas
Cool! Things move on! LEDs will come with a car attached one day!
That would not be difficult. (since anything without pistons cannot work in my view.)
In some parts of Essex, they do...
I dunno if it's exactly what you want, but you could try an LM3909
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It's a very efficient LED driver. I put one in a simple toy for a nephew, driven by a single D-cell - that was over 3 years ago and it's still flashing away - on the same cell! It's essentially constant-current drain (~0.1 - 0.5mA) when running, so you can get away with a resistor & zener for supply.
ROFLMAO.
They have made these since I was 10-11 years old! I used them in a project I made thats what umm nearly 14 years ago!
Ed
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