Newbie question... what is a 555 timer

[starmanmm]

Ok, newbie question.

Did a search on google but I still don't undestand what is the purpose of this and how is it used with leds?

[macfrank]

Ok, newbie question.

Did a search on google but I still don't undestand what is the purpose of this and how is it used with leds? :?

It's a very versatile integrated circuit that can be made to flash an LED at any rate and duty cycle (on vs off time) just by picking the right combination of two resistors and one capacitor. The output, by itself, can drive one LED.

It can also be used as a "clock" to generate a sequence of pulses that can be counted by a counter IC (like the 4060), giving you an even wider range of pulse combinations.

[starmanmm]

Ok, that info I understand.

Now I take it that when you buy one of these there is instructions that tell you what combo of resistors you need to make a led flash or is there a site that you plug in what you want it to do and it gives you that info?

[macfrank]

Ok, that info I understand.

Now I take it that when you buy one of these there is instructions that tell you what combo of resistors you need to make a led flash or is there a site that you plug in what you want it to do and it gives you that info?

The 555 has been out for more than 35 years; you could use the data sheet to calculate the values, or pick one of these online 555 calculators This one and this one are good examples. You typically want an astable circuit.


Frank

[starmanmm]

Thanks! Good info!

[Mr. Engineer]

Another IC which I like was the LM3909 by National Semiconductor, which, sadly, is now no longer exist. Its very good for flashing/strobe effects like for the Starship Enterprise.

[jwrjr]

There are single-chip computers in the same 8 pin package that don't cost any more than a 555, but can do the same job or a whole lot more.

[Mr. Engineer]

And one of them is the PIC12F629, which I just bought a few and am trying (unsucessfully) to glow and LED on and off.

But for the rest of my projects, its wonderful.

[jwrjr]

The 12F629 is good. The 12F508 is almost as good, and costs less. If you need programming assistance, I may be able to help.

[Mr. Engineer]

Thanks. I have an idea on using PWM for a project. But this wont see the light until next year as I am going to move soon and are packing all my stuff.

I think it has never been done before but then again, whatever I thought of, a few weeks later, someone already has done it. Grrr!