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

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.)
<p>Hello everyone,</p><p> I know this post is old but I'm hoping someone could explain something to me. I'm very new to this hobby of electronics/circuits &amp; robotics. What I don't understand is how the circuit is still made when the negative leads on the LDR are connected to the postive leads to the LED and same with the speaker? Any links or explanations will be greatly, greatly appreciated.</p><p>Thank you.</p>
<p>Good day!</p><p>I may be a 7th grader, but I think I have an answer. To me, the LDR is not an appliance; it does not consume electricity. It's just like a simple wire, so positive currents pass through it.</p><p>I hope this answers your question and have a good day!</p>
hii mate m gonna make this project cso i wanna ask that there is any wires or not
<p>Would these 'active' buzzers work? https://www.amazon.com/10Pcs-Plastic-Active-Electronic-Buzzer/dp/B00QC2UMNA/ref=sr_1_1?ie=UTF8&amp;qid=1472674720&amp;sr=8-1&amp;keywords=10Pcs+DC12V+Wire+Leads+Plastic+Active+Electronic+Alarm+Buzzer+Black</p>
<p>Its awesome Matt. :) Thanks. I never knew that the battery can conduct electricity through paperclips. :) this is for my science fair project. I'm in 5th grade. what do u think ill get? on a scal from 1 to 10</p>
<p>please make a video on how to make it please</p>
Thanks! This will be my son's introduction to electronics. He is 5 years old.
<p>Where do you buy all the supplies?</p>
<p>yea WHERE?</p>
<p>Mostly on-line but sometimes Radioshack. </p>
<p>That is fantastic!!! Tell him I said great job!</p>
<p>what kind of paperclips do u have?<br></p>
<p>The paperclips couldn't make the LED light, light light up</p>
<p>awesome </p>
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!
<p>That is great. Thanks!</p>
<p>Nice sensor! We are going to make this sensor using soldering, but we are wondering if the paperclips or the metal brads works as resistors? </p>
<p>I don't think the paperclips or brads resist much electricity. They are more like wires.</p>
<p>Where do you buy the supplies?</p>
<p>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!</p>
This is pretty cool. I haven't actually ever used a LDR.
<p>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?</p>
<p>This is brilliant. I'm new at this and as i dont have all the tools, it saved me. Thanks mate.</p>
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. &nbsp;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....<br><br>Good project BTW!!!!
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
This is cool, what a good idea!
Thank You
You are Genious <br>I Love It From Bottem Of My Heart
Hi, <br> <br>If you don't mind me asking, could you think of an electronic i could possible &quot;harvest&quot; an LDR from? Because I live in Canada and i unfortunately don't have the novelty of Radio Shack :/ <br> <br>- Bryan
Hi, Matt:<br><br>How are you? Great I hope.<br><br>What are the minimum and maximum required specifications for the following components,<br>That, will work with the 3 volt - Button Cell Battery:<br><br>(1) White or Blue LED,<br>(2) Piezoelectric Buzzer, <br>(3) LDR (Light Dependent Resistor)<br><br>Thank You, for your assistance regarding this question.<br><br>Take Care,<br><br>Wilfred Wheeler
i'm well thanks,<br>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.<br>Matt
its very simple to understand and cool idea!
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!
Thank you and good ideas.
its too gooood!
This is a great idea for teaching scouts electronics for the activity badge.<br>
This would go perfect with <a href="https://www.instructables.com/id/How-to-make-conductive-play-dough/" rel="nofollow">my conductive play dough</a>&nbsp;instructable&nbsp;for teaching circuits!
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. <br><br>Thanks for the nostalgia!
Really like how simple this is. You've got my vote. : )
This is a really nice project! I remember doing something like it when I was young.
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?
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? <br><br>Thanks and sorry but i dont know much about electricity and circuits but i want to make some cardboards love cards with your idea. <br><br>Thanks Again. <br><br>S.

About This Instructable




Bio: I'm a youth pastor in Minnesota. I went to Cornerstone University and studied Bible, Youth Ministry, and Psychology. I'm a Maker hobbyist for ... More »
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