I am frustrated.. help me.

[Eli]

And I can't fscking get it to work. What the hell am I doing wrong? It's 2 resistors and a cap, not exactly rocket science.

R1 goes between pins 8 and 7, and R2 goes between pins 7 and 6. C1 goes between pins 6 and ground. Pin 1 is ground, pin 8 is +5v, as is pin 4. Pin 2 is connected to pin 6(astable mode).

Simple. I'm using a 1k ohm resistor for R1 and a 10k pot for R2(so I could theoretically adjust the blink rate), and a .1mf cap for C1.

So why the fsck does my LED sit there and stare at me, not blinking? I thought maybe I fried the 555 chip messing around, so I went and got another.. same problem.

I'm pulling my hair out, I can't believe I'm having this much difficulty.. what the hell am I overlooking?



I'm following the directions found here....

 

[Heisenberg]

Did you check to see what the frequency it would blink at is? I used the formula on the link with your numbers and got ~685 Hz, which would be way too fast to see. But it's late, so you might double-check my numbers.

Edit: Is C1 0.1 microfarads, or 0.1 millifarads? I read it as microfarards the first time, which gives the 685 Hz. If it's millfarads, that gives you 0.69 Hz, which would be fine.

 

[helpme]

Aren't Microfarads labeled as MFD on the caps? (as opposed to uF). I can't find the schematic of the last lab I did with a 555, so I don't remember what I did that worked.

 

[cirthix]

by stare at you, do you mean constantly on or constantly off?

 

[Eli]

Finally, I got it working. Jesus H. Christ.

It was my capacitor.

I had tried other values, but I must have had something else wrong at the time.

The 0.1mf cap I was using doesen't seem to work. Well, it lights the LED.. but using it, the frequency must be so fast that I can't see it or something.

Using a cap in the 20 - 500uf range, and getting good results now..

I'm new to all this electronics stuff, even though I know the basics.. I'll get the hang of it.

I've got a bunch of DIY kits on order, to help further my knowledge and soldering skills.. It interests me a lot. I'll just consider this a small bump in the road and move on.

Often the most simple things are overlooked.. I knew I was building the circuit right, I just couldn't figure out why the fsck it wasn't .. blinking. Now I know.

 

[Analog]

Bookmark this page Eli:

http://ourworld.compuserve.com/homepages/Bill_Bowden/555.htm