Simple beam break sensor

[mackrackit]

http://www.uoguelph.ca/~antoon/gadgets/555/555.html
The above tells a lot about the 555. Try the metronome sample and step it up.

[The Master]

Ive had a read of that page and i tried the metronome example but its still not working. I didnt have a 250K variable resistor so i use a 220K normal resistor and i connected and LED to the output (and tried through a transistor).

Ive tried 4 different 555s now so im sure its not the chips that are at fault

[mackrackit]

Been awhile since I have played with a 555, but I seem to remember something about different types.

What are the numbers on you 555s?

[The Master]

I swapped to a different breadboard and its starting to look a little better. The metranome circuit worked. Ive put it back how i had it to start with and it seems to be oscillating but not properly.

The circuit ive been copying is the Infrared Emitter 555 Schematic.

The chips i have are NE555N. Aparently the ones that start with NE are good for driving LEDs etc directly

[mackrackit]

Mold...Mold on the bread board.

You may be picking up some stray capacitance someplace.

[The Master]

I think its just got a few bad connections on it.

The circuit still isnt working. Ive had a look at the output on my picoscope and its not a 50% duty cycle. I dont really know how to read the results properly but im pretty sure its the wrong frequency too.

Im gonna go sleep on it. My head hurt a little after reading that link you posted. I think ill go back to the metranome and mess with some values tomorrow.