Learn to solder – build a circuit kit – STEM skills

Learn to solder to be able to build electric circuit projects. With adult supervision, this project can be successfully done by sixth graders and up. Modern electronics involve printed circuit boards and components such as LEDs, resistors, and capacitors. Solder is a soft metal alloy that is melted to make joints to connect metal pieces. For safety, you should use a lead-free solder. The one we are using here is tin and copper. This project helps you learn to solder, how to identify resistors, and end up with a fun toy you built yourself!

Safety note: Be sure to explain safety precautions to children. High heat is used. Eye protection, long pants or apron, and closed toe shoes should be worn. Good ventilation is required. Disclaimer: All information provided on this site is for entertainment and education purposes only. Using any information from thecasabouquet.com is at your own risk.

Instructions for learn to solder

You may want to use a plywood board or very heavy cardboard to protect your work surface. The soldering iron gets very hot and should not be brought into contact with skin or flammable materials. Organize your work area so that the soldering iron electrical cord is safely connected to the wall plug. Use the instructions and diagrams included in the LED Robot Blinker Kit to assemble the kit.

To learn to solder, you may want to strip a few wires and practice soldering and desoldering on a prototype circuit board before working on your kit.

• Lay out the components for the LED Robot Blinker Kit and identify them. Use the resistor values chart to read the color bands on the resistors to find their values. Bend the wire legs and insert in the correct openings on the robot.

  

  

  
  
• Heat the soldering iron and apply a small amount of solder to the tip (this is called tinning). With the wrong side of the board facing you (green lines and metallic circles), hold the tip of the iron to one side of the resistor wire and heat for a few seconds. Hold the solder to the other side of the wire to melt and flow around the connection.
• Inspect the two capacitors and find the negative side (with the short leg). Place them in the circuit so the positive leg is in the positive hole. Solder in place.
• Inspect the transistors and find the flat side. Bend the wire legs as shown in the instruction book and place in the circuit so that flat side is lined up with the diagram. Solder in place.
• Inspect the 4 LEDs. Carefully notice the short leg and the flat side of the LED. Place the LEDs in the circuit board lined up with the diagram. Solder in place.
• Find the two loose wires, 4 inches long. Use the wire strippers to strip ½ inch of insulation off both ends of both wires. (You may need a screwdriver to set the wire stripper to the right wire size. It might help to practice stripping on another piece of wire first.) Solder one wire end to the center of the switch, another to the end of the switch, and the other ends to the holes on the circuit board.
• Place the red wire of the battery snap in the + hole and solder. Solder the black wire to the – hole.
• Snap in a battery and play with your creation!

The instruction manual has troubleshooting steps if the LEDs do not light or blink.

Supplies

• Soldering starter tool kit
  • Soldering iron, 25 Watt
  • Holder for soldering iron
  • Lead-free solder
  • Wire strippers and cutter
  • Desolder pump or wick
• Wall plug
• Safety glasses
• Elenco LED robot blinker kit
• 9V battery
• Stainless steel pot scrubber or damp sponge
• Helping hands with magnifying glass (optional)
• Hook up wire #22 gauge
• Printed circuit boards for practicing (optional)
• Paper or notebook for recording results

What is the science?

Content: electricity, electric circuits, LED, resistors, capacitors, transistors, electrical current

The LED (light emitting diode) is a semiconductor device that gives off light when a current passes through it. The brightness of the light depends on the amount of current. The resistors limit current (V=IR). The transistors can amplify the current and control it. The capacitors can store charges and can release them when needed. Soldering makes a connection between the wire of a component and the copper foil on a circuit board. A switch is used to complete the circuit with the battery. The time the capacitors charge up determines the blink rate of the LEDs. This kit is a parallel circuit.

Resource links

• https://www.youtube.com/watch?v=QL86gO9mfT8
  • Learn how to solder video from Electronics 123
• https://projects.raspberrypi.org/en
  • Resources from Raspberry Pi. A Raspberry Pi is an inexpensive small digital computer that can be used to make all kinds of projects.
• https://www.elenco.com/product-category/educational/
  • Educational products from Elenco, including soldering kits
• https://www.flinnsci.com/resources/safety-reference/
  • General Lab Safety resources from Flinn Scientific. Be sure to check out the Student Safety Contract.

Let’s talk story

I did not learn to solder until I was an adult. My mentor, Dr. John C. Park, taught me how in a workshop. I made bracelets out of telephone wire for practice and I was so proud! I had a strong commitment to soldering with the teachers and children in my workshops and camps. It’s a basic skill for electrical engineers and it’s not often taught in school. I love how it opens up the world of electrical device design!

I’ll be looking for comments below, or contact me at lisa [at] casabouquet[dot]com.

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