Mini Breadboards. How to use them

In this post I will try and show how to use a small breadboard.

The first picture here shows a small breadboard, with 170 points for connection. They come in many different colours, this one just happens to be green. The colour makes no difference to the operation.

 

I have added some row numbers and column letters to help clarify things. Most mini breadboards won't have this written on them. They don't need it, they are so small, but for the purpose of making things really clear I think it will help.

 

On each side of the central gap, the rows are connected together. This is done by a strip of metal formed into a "U" shape under the pin holes. So if I place a wire in (Row 2, column B) and a wire in (Row 2, Column C) they will be connected together.

 There are no "Power rails" on a mini breadboard, so I like to connect + and - into (Row 1). As you can see in the above diagram, this makes all of (Row 1 Columns ABCDE) -ve and all of (Row 2 Columns FGHIJ) +ve
Now we can go ahead and make a circuit! The blue lines represent "Jumper wires"
In this diagram I have connected a jumper wire from +ve to an unused row (Row 1,Column I to  Row 8, Column I) then a resistor bridges the gap by having legs pushed in to (Row 8, Column H and Row 8, Column B).
A second jumper wire connects  the resistor to a new row (Row 8, Column A to Row 5, Column A).
To complete this circuit, an LED is inserted. The longer leg is pushed in to (Row 5, Column B) and the short leg into (Row 1, Column B). If you have cut your LED legs, its easy to see which is the leg that goes to -, there is a flat edge on the rim. The flat edge indicates the - side.

 

To get a second LED to light you can connect them in "parallel". To do this, add your second LED with its legs into (Row 5 and Row 1). You can choose any of the pin holes still available on the left hand side, just remember what we said about the flat edge.

Another way would be to connect them in "series". To do this, remove the second jumper wire we put in. (The one on the left). Replace it with your second LED. Orientation matters! Make sure the - leg of your new LED is in the same row as the + leg of the first LED, and that the + leg of the new LED is in the same row as your resistor.

 Buy Mini Breadboards on our website here

That All Folks! Experiment and have Fun! Please let me know if you are having problems, or would like a fuller explanation on basic electronics.

LED Vu meter circuit using breadboard and LM3916 bargraph driver

LED Vu Meter – Easy

Overview / how it works:

This circuit uses the LM3916 LED Bargraph driver to give us a real time Volume reading on a set of LED’s.
It takes an input from the audio jack, connected to whatever music source you like, and reads the voltage.
It then works out this voltage as a fraction of the supply voltage and lights the LEDs connected to it accordingly.

You’ll notice the LEDs are all facing into the chip, as supposed to out of the chip, which would seem more intuitive.
However, this chip is using what is called a current sink as supposed to source.
This means instead of producing current on its pins to “drive” an LED, it regulates how much current is let into the chip to turn on an LED.
Effectively you can think about it as the chip varying the resistance between its pins and ground:
when the LED is off there is a high resistance from the pins to ground, and when it is on, there is a lower resistance.
This resistance has also been calculated so we don’t need protection resistors on the LEDs as we would normally.

The potentiometer connected to pin 6 of the chip allows us to vary the “high” trigger for the chip.
This means we can vary the top voltage of the range it is displaying,
so if the music you are playing is quiet, and the voltage from the input is therefore low,
you can use this to “turn up” the display.
Whereas if it is loud, you can compensate and stop the display from being on all the time.

 Building the circuit:

The parts list is as follows:

•  One LM3916 LED Driver
•  Ten LED’s (we used two red, three yellow and five green)
•  One 5.6KΩ Resistor
•  One 100KΩ potentiometer
•  One 9V battery
•  One Battery clip
•  One headphone jack
•  A breadboard
•  Some jumper cables

All the components can be bought from Mallinson Electrical or ordered online!

Last week we had two local students here for work experience.
Tom and Jacob are in to electronics, so we decided that a couple of projects would be the best way to engage them.
We tried to instill the importance of working to a deadline, and also to be able to work to a specification.
Overall, they did exceptionally well.
The first project was to develop a device which could send a GPS coordinate by Text (SMS). This being part of a larger ongoing project called "where is my car"

The basic idea is that when you leave the supermarket, the first thing you do is to impersonate a meerkat and crane your neck to try and spot where you parked your car!
The device we are working on allows you to text your car and receive directions to it.
This can be further developed to work as a lo-jack system, giving you the location of your car, and override of the ignition system should it be stolen.
You can see how this is coming along here
As it stands, you can send it a text, and it will return its coordinates. Why not give it a try. text the word "Location" to "07580 012305" and it will respond.

The second project is for a local Airsoft game zone. It involves sending data over an FM link to keep the scores of two teams. This is still in development, and we are working closely with the Airsoft guys to get this to do exactly what is needed.
At present we have a range of over 150m and can send serial data reliably in both directions.
More on this when it is completed. watch this space....

The electronic project kit is still proving really popular, 140 being sent in one order to a school in Adelaide, Australia. We have given a sample to a local school, who are looking at launching an electronics module to 180 students. They are considering the Night Light project, and will most likely do this as a soldered circuit rather than breadboard.
You can see the project and many others on our free projects pages

On a final note, while things are a little quieter due to the great weather, World cup and Wimbledon, I am finding occasional moments to work on a new animation. My first attempt at 15 seconds long, is showing on youTube, and getting a good few hits.

 Far and away the most popular video we are running is the "How to use breadboard" video.

We have been busy!
Check out the new website
www.mallinson-electrical.com

and remember to like us on facebook

www.facebook.com/MallinsonElectrical

Crystal Radio Set Review

Our Crystal Radio has been popular over Christmas. The following is a review (unedited) from Canada (Thanks Bob)

A few weeks ago I got sentimental about the Rocket Radio my father brought home for me in 1958.

He was a Merchant Marine Radio Operator.

Back then, we clipped a bed-spring to the aerial and I was able to listen to AM stations over a thousand miles away, at night.

Those little radios were about a dollar, back in those days, but they are expensive now.

But I discovered the Mallinson  Crystal Radio kit on ebay and optimistically ordered two, one for me and one for dear old dad, now 86.

They arrived promptly.

The boy in the illustration in the kit had his radio in a cigar box so I emailed Mr. Mallinson who suggested that "Any box will do."

They have great customer support.

At the Dollar Store I found two little coffrets in unfinished wood which I then stained and varnished.

 

 

And the instructions.

There is a little 6-pac of connectors which, when I inquired again of Mr. Mallinson, can be used as a unit, or separated depending on my preference..

So for a couple more days I studied the parts, off and on.

The instructions are clear and easy to understand.

 

I had salvaged a toilet paper roll for the coil, but between us we decided it was a bit big in diameter, so I unrolled
a remnant of tinfoil and secured a narrower form for our coil, and a bit heavier.  The wire is quite stiff,

While the varnish dried I studied the contents of the neat little box the kit came in.



I concluded that the project is a four handed job; somebody has to be a human vise.

A likely looking neighbour (Sam) dropped in this past Saturday and over coffee, I suggested we have a go at the first kit.

He agreed; then I kind of rushed his coffee while I collected the materiel for the job at hand on the kitchen counter.



We put 25 turns on one end of the roll and taped it nice and solid with packing tape, leaving generous leads, the ends of which we sanded, to connect them to the circuit.

With a hacksaw we sawed off the roll at a good length to fit in the box and allow for any adjustments we might have to make later.

I drilled a hole in the centre of the right front of the box for the capacitor.  Then we debated how to secure the little capacitor inside the box so it wouldn't tend to turn with the knob.

I was for taping it in with packing tape but Sam wanted a professional looking job so I got him a little chisel out of my toolchest and he carved a neat recess to keep the capacitor from turning.

There are two screw holes in the front of the capacitor so Sam suggested we screw it in securely; he's a regular perfectionist.

I went through my machine screw bag and found one little brass screw the correct calibre. Meanwhile Sam drilled it a hole and filed it a countersink with a little round file.

It is amazing, the tools one has on hand at my age.

So we screwed in the capacitor; unhappily our little screw proved a tad long and popped off the plastic back.  That snapped back on, neatly and we then filed the screw a bit shorter.

Hoping we hadn't bent the innards, we boldly went on...

We couldn't figure out a way to use the 6-pac as a unit, so we cut it up, crosswise into three pairs.

The rest was easy for a four handed team like us; the circuit is very simple.

Unhappily we couldn't get the plastic connectors tight  enough to secure the diode and resistor, so we elected to use solder.

We moved the whole operation to my workbench and heated up the soldering iron and tinned all the parts.

For this you need a wet sponge to wipe the soldering iron on.

I held the parts in place with needle nosed pliers while Sam soldered them; he had won a soldering award in a previous life and hadn't lost any skill.

Getting excited we trimmed the plug off the earpiece and soldered that in too.

Being in the basement we grounded the receiver to the furnace and flung the aerial as high as we could get it up the parts shelf.

We took turns listening as we fiddled with the capacitor.

We discerned some hopeful static.

Keep in mind that this was in the afternoon, underground, with a solar flare going on and  there are no AM stations anywhere near here.

We called it a day, but the intention is to buy a clamp from a repair shop to connect the ground to a water pipe in the kitchen, try the aerial above ground at night, with no solar flare.

This kit promises us hours of fun experimentation...

One footnote; our little wooden box was a bit thick and the shaft of the capacitor wouldn't extend quite far enough to top attach the knob so we are in the market for a different knob or perhaps we'll dig a deeper recess for the capacitor.

All in all a glorious jolly afternoon.  Pix follow.

--Bob
Shediac, Canada

Eureka!
Good signal on first try.

More experimentation in order as the volume is a tad low.


"Thank you for a great, and honest review Bob"- Andrew