Recreating Classic Electronics Kits alearn.sparkfun.com tutorial

Available online at: http://sfe.io/t93

Contents

Space-Age Science Fun!Collect The PartsDraw A LayoutAdd Spring ConnectorsAdd ComponentsHook It All UpTime For A Test Circuit!Resources and Going Further

Space-Age Science Fun!

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Do you remember these? Once upon a time, these electronic kits promised '1000s of experimentsin one!' and rarely failed to deliver. And, once upon a time, they taught me the basics of how tobuild a circuit.

The distinguishing feature of the cardboard "all-in-one" electronics kit is the spring connector.Circuits were routed by bending the springs, inserting a jumper wire between the coils and lettinggo. The pressure of the spring would make an electrical connection with the jumper and you couldput more than one wire on any one spring. Each component on the board was broken out to a set ofspring connectors, allowing the young inventor to design and build circuits without soldering or wire-wrapping.

We recently got nostalgic here at SparkFun HQ and started selling those spring connectors. Well, ithappened to catch me in the middle of a serious cardboard modeling addiction, so it wasn't longbefore I was building a SparkFun-ized retro electronics kit. After it was finished, I realized that theseare still a great way to play with circuits because they're laid out in such a way as to really inviteexperimentation. "I wonder what happens if I just connect these things in series" Try it! It only takes

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a few seconds anyway!

So in the interest of preserving history and sharing the magic, here's how you can build your veryown all-in-one springboard kit. We'll be putting together a simplified kit with fewer parts than the oneyou see above, but it should give you all the knowledge you need to design your own. Build it foryourself or for the young inventor in your life!

Suggested Reading

Before diving in to this project, make sure you have a good understanding of the conceptsmentioned below.

What is a Circuit? - To build your own circuits, you'll need to know what one is first.VIR and Ohm's Law - Use Ohm's Law to help you calculate resistor vaules for LEDs andmuch more.How to Use a Multimeter - The continuity setting on a multimeter is a great way to ensure thesprings are making a good connection.Polarity - Makes sure those polarized parts go in the correct way.Working with Wire - You'll need to use wire to make your connections between springs.Connector Basics - Learn which connectors you can add to your kit.How to Solder - Soldering isn't necessary to build this project. However, soldering yourconnections will increase the durability and lifespan of your kit.

Collect The Parts

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The first thing you'll need to do is collect all of the components that you'll want to include on your kit.I've chosen enough parts to build a transistor based LED flasher. Think broadly when designingyour kit and add enough parts to complete a wide range of experiments.

As well as the electrical components, you'll also need the crafting materials. The body of the kit willbe made of chipboard. You can get chipboard at just about any art supply store. The thickness isn'tcritical: it just needs to be thick enough to hold it's shape but not so thick that it's hard to get thesprings into it. You'll also need some material to make the legs on either side. Acrylic, wood,styrene, cardboard, anything rigid will work. Use whatever you're equipped to work with. Finally,you'll want some hot glue to fuse the two. Oh, and maybe something to cut with, a hobby knife isperfect. I cheated (as per usual) and used the laser cutter.

Here's a Bill-of-Materials:

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Space-Age Science Fun SparkFun Wish

List

(2) Electrolytic Decoupling Capacitors - 10uF/25VCOM-00523

Low-profile electrolytic decoupling capacitors 10uF/25V. These capacitors are great transient/surge suppresso…

(2) Transistor - NPN, 60V 200mA (2N3904)COM-00521

These are very common, high quality BJT NPN transistors made by ST Micro.**Datasheet: **[2N3904](http://ww…

Resistor Kit - 1/4W (500 total)COM-10969

Resistors are a good thing, in fact, they're actually crucial in a lot of circuit designs. The only problem seems to…

Trimpot 10K Ohm with KnobCOM-09806

There are lots of trimpots out there. Some are very large, some so small they require a screwdriver. Here at Sp…

Tactile Button AssortmentCOM-10302

These tactile buttons are great for all sorts of projects. This assortment comes with 2 of each of 6 different color…

(2) LED - Super Bright RedCOM-00528

These are *very* bright LEDs. The LEDs are so bright that it hurts to look directly at them. Please take a look a…

Battery Holder 2xAAA with Cover and SwitchPRT-09543

This 2xAAA battery holder puts a nice finishing touch on your battery powered project. This holder features a s…

(4) Spring Connectors (pack of 10)PRT-11822

If these spring connectors look familiar to you, they should. They have been used in a multitude of beginner el…

View Space-Age Science Fun on SparkFun.com

You'll also need:

ChipboardRigid Leg MaterialHobby KnifeHot Glue

OK, let's get to work...

Draw A Layout

Before we can place any parts, we'll need to decide on the layout of the board. You can draw thelayout by hand but I happened to have a laser cutter handy. You can have yours laser-cut at a localhackerspace or through a service like Ponoko, as well!

Here's the drawing that I made for my board layout:

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Featuring my retro interpretation of the SparkFun logo

The layout isn't particularly important but there are a few things to keep in mind. Generallyspeaking, you'll want to combine like parts and label them as a group. Also, try to keep in mind thatthis thing is going to be a ratsnest when you're using it, so make your labels big and legible! Finally,leave plenty of room between springs, as you insert wires, the springs will bend to one side and youwouldn't want that to cause accidental connections.

After feeding my creation to the laser cutter I made a couple of legs. I used acrylic but the materialisn't important, it's the shape that matters. You just need the experiment board to be basically flatbut raked slightly toward the user, there's traditionally a more upright portion toward the back of theboard as well. This helps the cardboard maintain rigidity. The more creases you put in it, the betteroff you are.

I cut a small hole where each of my springs will go, but you can easily punch those out using a ball-point pen as well.

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Now that we have a structure, it's time to start populating it...

Add Spring Connectors

The first thing to go in will be the spring connectors. These can be kind of a pain, but one trick that Ilearned to make the whole thing easier is to use a pair of pliers to bend the end of the spring out.This gives you something to stick through the hole and gets the spring started. Once in, simply giveit a few twists so that it screws its way into the cardboard. This is made less painful by grabbing the"wall" of the spring with a pair of needle nose pliers and twisting that way. Your hand is still gonnahurt after about 20 of them, though, so don't be afraid to take a break.

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Bending the spring makes it easier to insert into the board

Once all of your springs are in place, you should have something that looks like the picture below!

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Springs are in place but it's still missing something...

Add Components

Now take each of your components and find a home for it. If you haven't already, add holes for theleads of your component to stick through the chipboard. They'll connect to the springs on theunderside. For small components, they should be held in place by the bending of the leads. Thelarger components, like the battery holder, will need to be stuck to the chipboard with hot glue or apiece of double sided foam tape.

After all of your components are in place, it should look like the picture below. The next step is toconnect all of the component leads to the correct springs!

This isn't a bad time to add your supporting legs. Simply sit the chipboard on its side on top of oneof the legs and glue it in place with a bead of hot glue. Turn it over and repeat for the other side.Don't be afraid to really glob it on, as long as you're working on the backside, it'll look fine!

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It looks like we're done, but without anything connected on the backside, this will be a boring kit!

Hook It All Up

Carefully flip your board over and start bending your component leads toward their respectivesprings. If you have any polar parts, like LEDs, make sure you've labeled the spring connectorsaccordingly and connect them the way you've indicated on the front.

Some components will reach the springs on their own, but others will need a short length of wire.Even if a lead will hold itself in place under the spring, I like to add a bit of solder just to ensure asolid connection.

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Okay, we're all hooked up, time for a test!

Time For A Test Circuit!

Congratulations! You've built your very own all-in-one electronics kit. But wait! We don't knowwhether or not we've gotten our wires crossed. Let's wire up a test circuit. This is the fun part!

As you can see below, I haven't been shy in the application of jumper wires. If you're teaching theyoung inventor in your life, I suggest numbering the springs and then making them simple net listsfor them to follow. That way, they can "paint by numbers" until they learn how to translateschematics into circuits.

As for me? I've seen a few schematics in my life so it only took a few minutes to replicate a classicLED flasher circuit from a schematic that I Googled-up from the interwebs:

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Don't worry, that's what it's supposed to look like

Now when I press the pushbutton, the two LEDs should blink alternately.

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Woo! Blinky!

Hey hey! It works! I hope yours works as well!

These make a great gift and if you really want to impress someone then make up a little experimentbooklet to go with it! And heck, why not include an Arduino on your kit... or a 7-segment display...it's your choice!

Resources and Going Further

Now that you've built your own electronics exploration kit, you can start creating your own circuits!Here are a few other SparkFun tutorials that might help you on your way:

Pull-up ResistorsSeries and Parallel CircuitsVoltage Dividers

And once you've designed a circuit you really like, why not take it to the next level with theseprototyping tutorials:

How to Use a Breadboard

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Using EAGLE: SchematicUsing EAGLE: Board Layout

If you really liked these example kits and want to copy them, you can download the layouts in PDFformat:

ATmega328 Project Board LayoutTransistor Project Board Layout

learn.sparkfun.com | CC BY-SA 3.0 | SparkFun Electronics | Niwot, Colorado

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