Experiment 7: Relay-Driven LEDs

The Pregame:
In this experiment we play with a relay.  A relay has an iron core with a coil wrapped around it when power is passed through the coil the iron and coil create a electromagnetic field.  This activates a lever the pulls or pushes a strip of metal from one contact to another.  Essentially when you put power to a relay it switch the power from one contact to another.  What makes them so useful is a relay is normally activated by a low voltage then when the relay switches the contacts it switches the system to a large voltage.  This way you don't have to start an object with a high voltage.


**NOTE: For those without the book, the experiments now use 12 volts of dc voltage using a ac to dc universal converter.  This way you can just plug the thing in use power from your wall.

The Experiment:

Using this small relay with pin sticking out of it, your able to switch power from one LED to another.  Pretty cool...NOW when you hook it up the way in the book it should look like this:

WARNING: THIS TOOK A WHILE TO GET ALL THE CLIPS ON RIGHT.  This is one of the most annoying experiments so far in terms of putting it together, luckily this is the last time alligator clips are used THIS much.  You could also try electrical tape if urges to throw alligator clips through and out the window become to strong.

RESULTS: After fiddling around with the wires I got this:

or this if the video doesn't work:

Experiment 6: Very Simple Switching

The Pregame:

This experiment used two SPST switches.  SPST stands for single pole single throw switch.  This is just one of the many different types of switches out there.

When you flip (or throw) the pole on the toggle switch, it makes a connection with one of the contacts inside. In an ON-OFF switch one direction will make a connection with a contact allowing the electricity to flow through the circuit.  The other direction will make no connection to any contact, thus not allowing any electricity to flow through.  An ON-ON switch makes a connection with a contact in either direction.

 Single throw means there is only one pole making connections with contacts.  Different from double throw in which the switch is flipping two poles.



Making some switches:

I only ordered one ON-OFF-ON switch cause it was the cheapest, the difference here was I had to hold the switch in the on position, annoying but doable.

Using those cute little alligator clips again I was able to hook up the circuit as directed by the book.  The LED decided it wanted to work for me today and lit up.

RESULTS: it works

END OF PART 1: PART 2 SHOPPING

Part one of this book is done.  Part 2 get better as there be breadboards and transistors and the sort. We are now getting to the part of the book in which normal non-electric noobs wont be able to understand what you doing.  I feel smarter already.

NEW WEBSITES:

http://www.allelectronics.com/
Simple to navigate and they have most of the stuff for part 2.

 but for things not found there I would again stick to mouser or radioshack

http://www.makeuseof.com/
To entertain your inner nerd as your new electronic parts slowly crawl across the country.

WARNING: Amazon's shipping prices are not o.k. All they offer is disappointment.

Experiment 5: Let's Make a Battery

This experiment seems more like a 5th grade science lab then a way of teaching a electronic newbie electronic basics BUT I like this experiment for two reasons.

1) It reminds you electricity is indeed a natural phenomenon

2) It makes you feel like a little kid again, like when you turn on the t.v. and your favorite episode of Hey! Arnold is on.


The Pregame: Why lemons?

When two electrodes are immersed in a electrolyte the electrodes react chemically to the electrolyte and an electric current is produced.  In the lemon's case, the lemon juice is the electrolyte and the zinc coated nail/copper coated penny are the electrodes.  When the nail comes in contact with a strong acid they have a chemical reaction in which electrons are liberated from the zinc.  The free electrons quickly become crowded on the nail and need to find a way off.

When the penny is connected to the chemically reacting zinc (via a wire made of conductive material) the electrons rush off the zinc nail to the positive copper penny creating a electric current.

My Lemon Battery:

The nails (I used galvanized screws) and the pennies were sunk into two slices of lemon and connected to my little 1.5V LED, connections were made via thin medium gauge wire and the LED promptly proved it's useless worth by (again!) failing to light.














I checked the multimeter again and got this happy reading.



















Troubleshooting:

In my case the wired used did not work as expected as a more experienced electronic noob I'll would suggest using jumper cables or something of the sort.  I did actually get 2V from the lemon when one multimeter probe was put on the copper penny and one put on the screw.

RESULTS:  One disappointing LED, a obliterated lemon and 2 volts squeezed from a yellow fruit.

THINGS THAT MIGHT BE IN YOUR HEAD RIGHT NOW:

          Gatorade is indeed a electrolyte and you could theoretically pull some electric current from it if set up the same way.

         When life gives you lemons.....

       

 

       

Experiment 4: Varying the Voltage

This experiment asks you to use a potentiometer to make another circuit.

The Pregame:  What's a potentiometer?



A potentiometer (sometimes called pots) is a three terminal resistor.  One terminal is connected to the power source, one terminal is connected to the ground (material with no voltage/resistance), and one terminal slides across a strip of resistive material.  When you turn the knob you slide the third terminal across the resistive material and end up varying the resistance.

Setting up your circuit:

Connect the positive (red) cord coming from the 6V battery pack to the LED, the LED to the one side of the potentiometer, and the negative(blue/black) cord from the potentiometer to the battery pack.  Start with the potentiomter turned all the way counter-clockwise then rotate it.

.... forgot to take pictures of the circuit....here's a penguin.




RESULTS:  Well the LED got lighter the further I rotated it to a certain point, at this point the LED simply shut off.  I check the LED and noticed the voltage for it was rated for 1.5V.  After a certain point my LED gave up all together and left me with a dead circuit.

LESSON: Get LEDs with the right voltage rating, 1.5V LEDs are wimpy.