Picture of Build a Simple Circuit from a Pizza Box (No Soldering)
I learn best through tactile teaching methods.  Teaching and learning basic circuits, electronics, and electricity from books is good, but why not build a simple circuit from scratch and learn from doing.  This is a great way to get hands on and teach/learn the basics of electricity.  With this project you can change the path of the electric current to run through different sensors.  With this design you can switch between lighting a Blue LED or activating a Buzzer.  You also have the choice of using a Light Dependent Resistor with the LED or Buzzer.  You can be creative and design your own circuit and add different sensors (other LEDs...).  

Step 1: Parts

Picture of Parts
Here is a list of the parts needed for this project:
  • 1 - Pizza Box/Cardboard  (I used the bottom of a pizza box.  Make sure it is clean.)
  • 1 - White or Blue LED  (I would stay with those 2 colors because they can handle 3 volts, other colors would need a resistor.)
  • 1 - Piezoelectric Buzzer
  • 1 - LDR (Light Dependent Resistor)
  • 1 - 3 Volt Button Cell Battery
  • ~ 25 Metal Brads  (I used large brads, small would work too.)
  • ~ 20 Paperclips
  • Small Nail (or something to poke holes in the cardboard)
  • Tape  (I used black electrical tape on the underside and white tape to hold it closed.)
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AgIC2 months ago

Amazing! So nice that you are sharing some tips for others to replicate your project! How long did it take to complete this project? Thanks!

shane better3 months ago
This is pretty cool. I haven't actually ever used a LDR.
squish0599 months ago

My buzzer will not sound when I switch the circuit through the light dependent resistor (LDR). I can barely see my light dimmed through the LDR. I have tried connecting extra batteries in series. Obviously shining a light on the LDR brightens the LED, but nothing seems to help the buzzer. Any ideas?

Logan Rolfy11 months ago
Brilliant! I just read it... If we all did this instead of breadboards, a lot of money would be saved! Thanks!!! I also love ur iPod charger... Ive built it!
jbatista f1 year ago

This is brilliant. I'm new at this and as i dont have all the tools, it saved me. Thanks mate.

TechwizWood3 years ago
I tried this and I am having a problem getting anything to work. I went to staples to buy paper clips and the brads and I am wondering if these paper clips have some type of coating prohibiting the flow.  Has anyone run into this problem?
I have run into the same problem and it was the brads that where coated with a clear non conductive material. had to sand them
I didn't run into the problem, but you certainly cannot use the colored plastic coated paperclips. The old fashioned bare metal ones are conductive...the plastic will just insulate the metal....

Good project BTW!!!!
matt.e.jenkins (author)  mrmadison3 years ago
I have been away, thanks for your input. I would just add that if you have a voltmeter you can check for small shorts (gaps in the circuit) you may have not have seen. Thanks
Love It
foobear3 years ago
This is cool, what a good idea!
matt.e.jenkins (author)  foobear3 years ago
Thank You
You are Genious
I Love It From Bottem Of My Heart
bajtees13 years ago

If you don't mind me asking, could you think of an electronic i could possible "harvest" an LDR from? Because I live in Canada and i unfortunately don't have the novelty of Radio Shack :/

- Bryan
hevengineer3 years ago
Hi, Matt:

How are you? Great I hope.

What are the minimum and maximum required specifications for the following components,
That, will work with the 3 volt - Button Cell Battery:

(1) White or Blue LED,
(2) Piezoelectric Buzzer,
(3) LDR (Light Dependent Resistor)

Thank You, for your assistance regarding this question.

Take Care,

Wilfred Wheeler
matt.e.jenkins (author)  hevengineer3 years ago
i'm well thanks,
I am not sure if understand your question but with 3 volts a white or blue LED will work but only one. The buzzer will work but not at the same time as the LED and any LDR can be used as you wish. Feel free to ask again if you have questions.
bhushan213 years ago
its very simple to understand and cool idea!
matt.e.jenkins (author)  bhushan213 years ago
kostya3 years ago
Great idea for breadboarding simple circuits! I would substitute a LED with a blinker. Another possible enchancement is to hook up a music chip and a piezo disk instead of a buzzer. I vote!
matt.e.jenkins (author)  kostya3 years ago
Thank you and good ideas.
yhdesai3 years ago
its too gooood!
sds73 years ago
This is a great idea for teaching scouts electronics for the activity badge.
This would go perfect with my conductive play dough instructable for teaching circuits!
SHIFT!3 years ago
I love this project and admire the simplicity of how taking something as complex as electronic circuitry and simplifying it so that anyone can understand it. I remember having something like this in my 3rd grade science class and was absolutely loved it.

Thanks for the nostalgia!
Aquilla3 years ago
Really like how simple this is. You've got my vote. : )
matt.e.jenkins (author)  Aquilla3 years ago
tylervitale3 years ago
This is a really nice project! I remember doing something like it when I was young.
matt.e.jenkins (author)  tylervitale3 years ago
Thanks, me too. In 7th grade I think.
to make the led go brighter in shadows i would need to connect it in reverse yes?
matt.e.jenkins (author)  curious youth3 years ago
The LDR would do the same ether way you connect it. To make it go brighter in shadows would be a different circuit and i don't know it off the top of my head.
No. That would cause some serious issues.
Hi. Nice instructable. I really will try something like this.. But i want to ask you something. If i want to use more Leds to make a heart or something like that and i need more volt (a mayor number of bateries or a bigger batery) how do i know the limits of volts to be safe? i mean if i put a AA batery or 2 can it be safe to be manipulate the Paperclips or Metal Brads with hands?

Thanks and sorry but i dont know much about electricity and circuits but i want to make some cardboards love cards with your idea.

Thanks Again.

Usually it will be safe unless you're working with high voltages (at which point paperclips and batteries shouldn't be involved)

an AA battery is 1,5 volts so he actually used 2 of those for this project. You can go higher without problems. (although I'd say don't go over 4 as it's not needed for any project for testing like this)

Instead, you can also hook up the LEDs next to eachother (parallel) in stead of behind eachother (series) meaning that you won't need more voltage then with only 1 LED
matt.e.jenkins (author)  Ganoderma3 years ago
Thanks Ganoderma, I was about to say the same thing. Thanks S. I'm glad you liked it.
Very nice indeed! Thank you!
matt.e.jenkins (author)  lahorichargha3 years ago
Glad you liked it.
canucksgirl3 years ago
Thank you! - This is fantastic. I am a noob to anything electrical, but this reads very well and I already understand more than what I have tried to learn from several other sources.

Great Job. you got my vote :D
matt.e.jenkins (author)  canucksgirl3 years ago
Thanks for your vote and the kind words. I'm glad it helped.
iRuKuS3 years ago
Very nice i will use this to teach my 7 year old son thanks!
matt.e.jenkins (author)  iRuKuS3 years ago
It was my pleasure. When you are done, go ahead and post a picture of what you came up with so we can see it. Thanks
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