Very Basic Breadboard Question

Hi,

I’m completely new to electronics (radiologist by background and hobbyist software developer).

I’m having trouble getting even the most basic circuit setup on my breadboard. I’m basically trying to get an LED to light up constantly (following the tutorial on ladyada.net without much success. Can somebody take a look at these two photos I’ve attached to see why the LED won’t illuminate?

I’ve tried three LEDS and three different value resistors (each both ways round) but the LED never lights up. The red wire in the picture is connected to the 5V pin and the black wire to the GND pin. The Arduino is plugged into the USB port on my laptop and shows the green power light and is running the example Blink() program.

Sorry if this is the dumbest of all questions but I’m clearly doing something fundamentally wrong!

Many thanks,

Assuming Im reading your breadboard correctly... Theres no connection between the positive rail and the resistor.

You can either use a small link from the positive rail to the resistor, or just connect the red wire direct to the resistor (to the end with the brown stripe).

That looks like a 1k resistor (Brown Black Red) in the photo, which is too high for a 5v supply. Use a 220ohm (Red, Red, Brown) or 33oohm (Orange, Orange, Brown) is the prefered values to use for a 5volt supply.

You need to figure out which holes on the whiteboard are connected to which other holes. Looks like you have the wrong idea there.

If you remove the whiteboard and just hold the wires to the led + resistor leads by hand, you should get light. Start there, then plug in the whiteboard.

FieldDoc:
Hi,

I’m completely new to electronics (radiologist by background and hobbyist software developer).

I’m having trouble getting even the most basic circuit setup on my breadboard. I’m basically trying to get an LED to light up constantly (following the tutorial on ladyada.net without much success. Can somebody take a look at these two photos I’ve attached to see why the LED won’t illuminate?

I’ve tried three LEDS and three different value resistors (each both ways round) but the LED never lights up. The red wire in the picture is connected to the 5V pin and the black wire to the GND pin. The Arduino is plugged into the USB port on my laptop and shows the green power light and is running the example Blink() program.

Sorry if this is the dumbest of all questions but I’m clearly doing something fundamentally wrong!

Many thanks,

It is only a dumb question if you don’t ask it, and it hampers you. Remember none of us were born doing this, we all had to learn (and BTW, I’ve only been doing it for a month or two).

If I can suggest posting smaller pictures in the future. Some browsers do not automatically reduce the image to the screen size, and some people need to worry about bandwidth that larger pictures produce.

From what I can gather from your picture, you have the breadboard backwards. It looks like you are thinking everything in column C is hooked up together, while instead breadboards are organized as rows – everything on the right side of row 2 is hooked up together. This means the resistor on row 2 has nothing connected to it. The LED has a connection to ground on one leg, but nothing is on row 1 to connect to it. Finally, there is no back circuit to the power (red) connector.

Terry King has better words to describe a breadboard in his yourdunio.com page: http://arduino-info.wikispaces.com/LowCostStarterSet-Connecting-Breadboarding

On each row, columns A-F and G-L are connected together. So, A1, B1, C1 ... F1 are connected together, and G1 ... L1 are connected together. Ditto for A2 ... F2 and G2 ... L2, etc. Right now, this means you have the resistor connected to itself, and not to anything else. Not too useful.

Try these connections: Short leg of the LED into the ground bus. Long leg of the LED into C1. One leg of the resistor (doesn't matter which; resistors aren't polarized) into D1 (this connects it to the long leg of the LED--remember A1 ... F1 are connected together). Other leg of the resistor into D3. Wire from A3 to the positive bus bar.

Presuming your resistor is a reasonable value (i.e., somewhere around 220 ohms up to maybe 1k), this should make the LED light up whenever the bus bars have power/ground from the Arduino.

Thank you everybody for your clear explanations. Not connecting the power rail to the "main" bit of the board was an oversight on my part :%

You were definitely correct about my understanding of the connections, I didn't realise power went from a1-f1, I thought all column A was connected, etc.

Thanks for clearing things up - it now lights up!!

Ain't that a hell of a feeling... when it works for the first time???. That I think is what it is all about for me and I've been doing this for many years.

Doc

We all live for those eureka moments :slight_smile:

Yes, seeing something you created come to life for the first time erases all the frustration that you felt while building it.

Now for some real excitement. Make it BLINK!

hoff70:
Now for some real excitement. Make it fade in and out using PWM!

Fixed.