LED Flasher/strobe Circuit

[AllVol]

The PIC costs more and does not provide the current for an impressive flash.
D.

My PICaxe cost less than three dollars, and each output pin emits 25ma, more than enough for a LED.

The program places a .1 second pause between individual flashes, and a .25 second delay during the switch from left LED to right LED.

I think it meets the design criteria posted originally.

All Vol

 

[audioguru]

I made some LED "flashlights" that are blindingly bright, like strobes.
The LEDs have a max continuous rating of 30mA but 100mA when pulsed. So my circuit pulses the LED for a short duration 5 times at 100mA then a pause before blinking again. I used a CD4001 to make a pulsing oscillator and a slow repeating oscillator. The LED is driven by a transistor. A 9V battery powers it and a 5V low dropout regulator keeps it working the same until the battery is dead.

 

[cadstarsucks]

I made some LED "flashlights" that are blindingly bright, like strobes.
The LEDs have a max continuous rating of 30mA but 100mA when pulsed. So my circuit pulses the LED for a short duration 5 times at 100mA then a pause before blinking again. I used a CD4001 to make a pulsing oscillator and a slow repeating oscillator. The LED is driven by a transistor. A 9V battery powers it and a 5V low dropout regulator keeps it working the same until the battery is dead.

The spec is 100mA pk at 1KHz and a 10:1 duty cycle. Max brightness is achieved at that point and is approx 3x nominal, I believe. The best efficiency that can be had is achieved using a small boost regulator with the enable pin doing the switching and a sense resistor to the feedback pin to regulate the current.

D.

 

[AllVol]

Need to flash twice quickly on 1 pair then change to other pair and keep alternating similar to emergency vehicle type but to run a small battery.

Steve

Perhaps emergency vehicles in cadstarsuck's part of the world do not flash like he is talking about. That's where his timing request came in. (original post)

He later talked about placing the assembly in a model car.. hence the compact version.

Thanks for the input,
AllVol

 

[cadstarsucks]

Perhaps emergency vehicles in cadstarsuck's part of the world do not flash like he is talking about. That's where his timing request came in. (original post)

He later talked about placing the assembly in a model car.. hence the compact version.

Thanks for the input,
AllVol

Honestly, I don't pay a bit of attention to them as they hurt my eyes. The circuit I posted earlier actually turns one on for 250ms (accept the resistor, I think should be 25K instead of 50) off for 250 on for 250 off for 250, repeats for the other and then repeats...

Hmmm... that's what I get for rushing through something when I am supposed to be working. It looks like it does exactly what you were describing. It is an 8x250ms state cycle that turns on one twice and then the other twice.

D.

 

[cadstarsucks]

D., that's pretty slick.
I think I would invert clock with one of the unused inverters and drive the anode of LED2 with it. It would make the timing more 'symmetrical'. In fact, I think I would buffer the clock for both LEDs, just to be sure I'm not going to have marginal clock logic levels.
You could also run off QB and QD, which would allow a smaller timing cap - admittedly no big deal.
It still has more parts and requires more space than the microcontroller version.
As you said, it's probably cheaper, at least for a one-off.

Very good...I was going for bare minimum as I was under the impression that most here are looking for the simplest ways to achieve their goals as opposed to the most accurate.

D.

 

[Roff]

Very good...I was going for bare minimum as I was under the impression that most here are looking for the simplest ways to achieve their goals as opposed to the most accurate.

D.

I was just figuring that the extra inverters are free, unless this is part of a bigger system.

 

[AllVol]

Honestly, I don't pay a bit of attention to them as they hurt my eyes.
D.

I try not to look at them either... they hurt my pocketbook. hehe

My suggestion was merely one way to answer the guy's question. There are as many solutions as there are brains to think of them and money to buy them.

Your suggestion for the LS3xxxx made me take a look at that... just what you were trying to do, eh?

Regards,
AllVol

 

[Nigel Goodwin]

Off thread 'drift' moved to own thread at

Moderator.