Design BriefBattery Tester

Situation/ChallengeYour world is full of electronics! Using your experiences from your soldering practice, the Soldering Guide, and your experiences and knowledge from the Mr. Circuit lessons, build a 9-volt battery tester.

Criteria & Constraints Follow ALL soldering safety rules. Your battery tester must work before you take it home. Use only the tools, materials, equipment provided.

Tools, Materials, Equipment Tile (at your workstation) Soldering Iron Soldering Iron Stand Needle nose pliers End nippers Wire strippers Heat sink Solder Circuit board LED Resistor – 5.6 Battery snap 9-volt battery – used to test to see if it works

Procedure1. Identify the Need or Problem

In your Engineering Notebook, restate the challenge in your own words.

2. Research the Need or Problem – use the Internet for this In order to understand how electronic circuits work, you must first know and understand

what electronic schematics are. In your Engineering Notebook, write what a schematic diagram is.

Find at least three examples of schematic diagrams that use at least 2 symbols of components that you learned about during Mr. Circuit. Record and sketch these examples, name the electronic devices that the schematic diagram represents, label the components in the schematic diagrams, and site the sources where you found these examples.

You will use an LED in your battery tester. Find at least three more items that use an LED, record them in your Engineering Notebook, and site the sources where you found them.

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You will also use a resistor in your battery tester. Why do you think resistors come in so many different values? Think about this question, and record your answer in your Engineering Notebook.

Now, in your Engineering Notebook, sketch the physical appearance of the components that you will use for the battery tester circuit.

On these sketches, label the polarities (+, -) for each of the components’ leads. If unsure, go back and check your Mr. Circuit notes, ask your partner, check the Internet, or as last resort ask a teacher.

3. Develop Possible Solutions You do not need to develop possible solutions for your battery tester.

4. Select the Best Solution The best solution for creating this battery tester was selected for you.

5. Construct the Prototype/Model Push your computer way back out of the way.

ALL SOLDERING PREP & WORK IS DONE ON THE TILE!

To prepare your components, you will need to strip back (remove) at least ¾” of the insulation from the end of the battery snap leads using the wire stripper. Click to watch the wire stripping video – watch as many times as you need to understand how to do this.

Remembering back from your Mr. Circuit lessons, in order for a device to work, it must be in a complete circuit.

Study the schematic diagram above – it shows a complete circuit. In your Engineering Notebook, draw the assembly diagram (physical appearance of the circuit) showing each component’s placement on the circuit board:

o Draw this assembly diagram in an 8-hole by 8-hole area.o You must have at least two holes between each component lead.o Show how you will connect each component to create the complete circuit.

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Now you will need to profile your components. The flatter components are always soldered first, followed by the taller components.

Remember to use a heat sink when soldering the LED – check back in your Soldering Guide on how to use a heat sink if you need to.

Now look back at your assembly diagram that you drew in your Engineering Notebook. Place your flattest component first, and solder it into place on the circuit board. Remember to always solder on the shiny side! See picture below.

Solder your next component in place on the circuit board, and then finally solder your tallest component. See picture below.

The back of you finished circuit board should look something like the picture below. Your solder joints should not touch – this will short your circuit out.

You will now make the circuit complete. Gently bend the component leads to touch each other as shown in the schematic diagram and twist the leads together. Be sure to have your polarities (+, -) correct. See pictures below.

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Using the battery from Tools, Materials, Equipment, test to see if your complete circuit works. Your LED should light up. If it does not work, troubleshoot the problem by using the steps below:

o Area all the twisted joints making a connection?o Do you have the circuit set up correctly according to the schematic diagram?o Area the component polarities (+, -) correct?

Make any corrections by doing the following:1. Un-twist the incorrect components.2. Re-twist the components in correct polarities.3. Retest – repeat if necessary.4. If all else fails, a component may be bad, so ask a teacher for help.

Once you have your complete circuit, solder your component leads together where you twisted them – REMEMBER TO USE THE HEAT SINK WITH THE LED! Your battery tester should look something like the pictures below.

6. Test and Evaluate the Solution Test to see if your battery tester works by using a 9-volt battery found at the Tools,

Materials, Equipment area – the LED should light up.

Write WORKS in your Engineering Notebook. o Show a teacher that it works, and they will sign your Engineering Notebook.o Once a teacher has signed your Engineering Notebook, use the end nippers and

carefully cut the excess lead wire off ABOVE THE TWISTED SOLDER JOINT – see picture below.

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7. Communicate the Solution In your Engineering Notebook, sketch what the back of your circuit board looks like.

Include the following in your sketch:o Label each component.o Label the polarity (+, -) of each component.o Draw an arrow showing the flow of electricity.

8. Redesign or Improve You will not need to redesign or improve your battery tester.

9. When you’ve completed your home, explore some of the games at the Try Engineering website: http://www.tryengineering.org/play.php

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For this design brief and more, visit our webpage:

http://www2.westside66.org/~dshabram