Breadboard Question

[SparkyCal]

Hi Guys.... I bought a bigger breadboard. Here is the one I bought:

https://www.amazon.ca/gp/product/B00KHE7O7Q/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1

I am wondering what the two busses on the top are used for. Presently, I am using the top horizontal buss to run my + and - to the posts and then to all the breadboard rails. But I am not sure why there is a second horizontal rail directly underneath the first. At first I tried daisy chaining those two busses, but my power supply started showing a short. So, that second rail must be independent of ther first, but I am not sure for what use.

Also, wondering why 4 posts are included. I assume you can use the green one for ground, or for a mid point if you are using two power supplies, but why is there a green and blue one in addition to the red and black?

Thank-you. I was watching some YouTube video and I found the board, but I could not find someone addressing the question above.

 

[Martaine2005]

A continuity test will check which rails are which. This is a good guide from RS.
Looks like it's 4 breadboards clipped together and the top two are the side power rails used by themselves.
The coloured posts are +V, 0V, -V and Gnd. Or whatever you want them to be..Some have a yellow too.

Martin

 

[bertus]

Hello,

Some breadboards have the curlpit of a open power line in the middle:

Bertus

 

[Harald Kapp]

One important measurement to take before you start building circuits on this board; Check continuity of the power busses (red and blue markings) along the length of the board. I do own such a board and the power busses are interrupted in the middle. Easy to fix with a few jumper wires:

Your board may or may not need these jumpers. But if the power busses are interrupted, you might spend hours of searching for a fault in your wiring when only there is no power to your circuit.

 

[SparkyCal]

Thanks for the explanations and pictures. I will check the gap and use jumpers if need be.

it reminded me of one time, I built the distortion circuit perfectly but it would not work. After racking my brain for an hour, I noticed that the cable was not plugged into the guitar. Lol