LED strobe light

Simplest: Microcontroller directly drives a logic-level-input MOSFET, turns on at the 100Hz (or lower) repitition rate, turns off at a time to determine brightness. If you turn on the LED for 1 ms, it will be half as bright than if you turn it on for 2 ms. Current limit the LED from a fixed supply through an appropriate resistor.

The *simplest* circuit hardly requires a microcontroller !

Graham

Then use a PIC, slightly better than a 555

martin

A 555 has enough oomph to drive a led directly at a decent current though.

Graham

Typical 1W Luxeon LEDs need 350mA, which is a bit much for a 555.

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Is that '1W rating' a typical Luxeon spec ?

Graham

Yes and there are also bigger ones. If you really want to go nuts try Lamina which can go over 100W (red) Digikey 521-1006-ND

--

    Boris Mohar

Kind-of. They have I/II/V models that have input power of roughly

1W/3W/5W, and that's how they are often marketed. The V Star type are 700mA at 6.8V typical. The I Star ("1W") are only 350mA @ 3V-3.4V typical.

Best regards, Spehro Pefhany

--
"it\'s the network..."                          "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

Nonsense! Perhaps you'd better read the requirements statement again; "with microcontroller control".

--
   Keith

Which is why I phrased my answer as I did.

Graham

Geez Pooh, I thought you were a businessman. He asked for a solution

*specifically* using a microcontroller and here you are telling him that it's the wrong solution. Perhaps he already has one in the design? Sometimes a microcontroller *is* the right answer (particularly when the customer asks for one).

--
  Keith

that

the

Especially when it only costs $1 and can control BOTH the perceived brightness (via high rate PWM) and the strobe rate. You'd need a 556 to do that and they're $1.44 single qty at DigiKey. ;-)

I have often found that ppl are chasing the wrong solution, usually on the basis of bad advice or incorrect assumptions.

The OP asked for simple.

Quite often ppl get 'wrapped up in technology' for the sake of it and simple becomes not so simple. If we knew *why* he wanted a uC maybe it would make more sense ?

Graham

You have some funny ideas ideas about the price of commodity ICs.

Graham

Perhaps it's you who have the incorrect assumptions?

UCs *are* simple. Transistors are free. It's the packaging that cost$. ;-)

It makes sense because that's what he asked for. Maybe you want to ask for the whole problem, rather than assume a UC is the wrong solution?

--
  Keith

556 to

How's that? What are you paying for 556's? It seems only natural as micros come down in price that they will displace more and more of the specialty market. This can only drive the price up further on those parts. I'd say that you need to face the fact that microcontrollers are going to be the chip of choice for the future, even if it does seem like overkill.

and

solution

that

on the

when the

cost$. ;-)

and simple

would make

ask

Here here! I get the idea that Pooh doesn't "dig" micros, period.

You'd be very mistaken.

I have actually designed in micros where they once would have seemed an unusual choice.

It's a question of the right tool for the job.

Unless the strobe led needs to be remote controlled, I see no reason for a uC.

Graham

Farnell has them in ones for GBP 0.26.

Digikey has them at a qty prcing of USD 0.14

Show me a uC for under 50 cents ( never mind under 14 cents ).

Show me a uC that has 200 mA drive capability.

Graham