# Help with circuit?

1. Dec 4, 2012

### Zatara7

Hello, I need help with this circuit. I didn't post this in the homework section because it isn't homework I'm just doing this for fun.
circuit:
http://imgur.com/i5fSX [Broken]
image isn't working so here's a direct link: http://imgur.com/i5fSX [Broken]

It is a 5 V input and three 100 OHM resistors in series and one LED. I can't measure current through it because fuse on multimeter died. I'm sure that 5 v is coming in because I tested that and the resistors are 100 +- 5 ohms I tested that too.
I have these leds (http://www.radioshack.com/product/index.jsp?productId=2062588) from radio shack and people on the website say that I need around 300 ohms at 5 volts to run turn them on but nothing.

I hope you guys could help out a circuit noob

Last edited by a moderator: May 6, 2017
2. Dec 4, 2012

### yungman

You know you have 100Ω resistors, measure the voltage across the resistor, then calculate using:

$$I=\frac V R$$

3. Dec 4, 2012

### Zatara7

Weird, I'm getting zero voltage across the resistor

4. Dec 4, 2012

### the_emi_guy

It looks like you are off by one hole in a couple of places. Rows of holes are connected, columns are not.

5. Dec 4, 2012

### Zatara7

Thanks a lot man. Yea this breadboard is different from the one we use in class. I was looking at everything else but it was just this simple fix.
after I measured the voltage now I'm getting 0.1667 like expected :)

thanks all for input