#0017: Creating a Toy Drag Racer Car

Prelude

This will be the first in a series of articles on making crap from garbage. I intend to build on this initial car, by adding more functionality and complexity down the line later. The purpose of this series of articles is to illustrate how accessible our hobby actually is. All you really need is access to information, basic tools, and most importantly: a little motivation and imagination.

Basic drag racer toy car.

As you can probably tell from the pictures; this toy car once had additional components that I removed for this write up. These included: 4 LED “””head-lights””” (2 white, 2 red); a jumper cable and switch, to allow the motor to be run using only one of the batteries at a time (for a slower speed); and additional wiring to allow the motor to run in reverse. Essentially whatever bollocks I felt like lazily sticking into the thing.

This should however illustrate that you can keep adding complexity to the basic frame work … Yeah, that’s why I reused the same haggard little tupperware container with the two unused switches: to make a point. It wasn’t abject laziness at all. Nah.

One could even keep adding complexity and replacing components until a simple drag racer can turn into a self steering robot. This could be done by using ultrasonic sensors, microcontrollers, and servo motors just as an example. However the basic framework is a good starting point.

Toy demonstration

Making the thing.

Tools and materials.

So what do you need to make this masterpiece? A soldering iron will help but twisted wire connections and electrical tape will do. Work with whatever you have on hand. I’ll just list out what I used.

Tooling:

• soldering iron
• heat gun
• DC power supply
• multimeter
• precision knife

Consumables:

• electrical tape
• heat shrink
• hot glue

Materials:

• wires
• tupperware box
• gears and wheels kit
• switches
• AA battery holder
• AA batteries
• rubber-band (elastic band)
• 3 volts DC motor

Build process.

Its largely self explanatory from looking at the pictures but I’ll give ya a quick write up if you insist on reading. Nerd. Anyway, get either a cheap wheels and gears kit (yes I am a hippo-crit) from an online store, or salvage wheels from broken toys if you have any, or use bottle caps even. You can even make decent wheels from either cardboard or by working random stiff plastic with a saw and a file.

Next, cut appropriate holes into the plastic box, sardine can, old butter tub, or whatever you’re calling a chassis. Then affix the motor into the chassis using hot-glue or tape. I wanted to use a belt driven system for no other reason than I wanted to use a belt driven system. So I used a couple of belt pulleys from the gear kit and a near dead elastic band as a drive belt. I know what you are thinking, and yes it is very unreliable.

If I were to redesign this for simplicity and reliably; I would just insert the motor directly into one of the rear wheels and power it that way. Better yet you can use two motors, one for each rear wheel. Anyway, next, throw in a switch, a useless fuse just for fun, and an occupied battery pack. Done. Enjoy.

The project is so simple it seems silly didactically going through every step of slapping it together. Just look at the pictures: yours should be like that but good. The point is to make it using the materials on hand. Improvise as a matter of course.

One thing that might be good to improvise on is by using a salvaged battery holder if you can not find one. I know not everyone has access to broken Poundland fairy lights. For example the motor here came from a cheap hand held fan. I could easily use it’s chassis moulded battery holder instead and just butcher it to fit. No worries.

To source the material I recommend a discount store like the aforementioned Poundland or the 99P shop. You could probably get all the materials for less than a fiver. And if you’re really on a budget, then I recommend the dumpster behind Poundland. Don’t ask me how I know.

Belt demonstration

Schematic

It’s not really necessary given the simplicity of the circuit. But I’ve included one never the less for the sake of completeness.

Circuit power use.

To satisfy some curiosity I decided to measure the power usage of the motor, and power delivery that the batteries can supply. I did it to give me an idea of how much power the batteries are able to provide, and how much of that available power the single motor uses. That way I’d know what’s limiting performance, should that become a concern. And it will once I decide to start adding components, such as additional motors.

Results:

Tested with a 6 Ampere max bench power supply against mismatched old batteries. Guess which performed better?

(BPS = Bench Power Supply)
BPS powered Motor (spinning freely): 3V @ 0.25A (0.75 W)
BPS powered Motor (jammed): 3V @ 2.71 (8.13 W)
Battery powered Motor (spinning freely) #1: 3V @ 0.18A (0.54 W)
Battery powered Motor (jammed) #1: 3V @ 2.02A (6.06 W)
Battery powered Motor (spinning freely) #2: 3V @ 0.29A (0.87 W)
Battery powered Motor (jammed) #2: 3V @ 0.70A (2.10 W)

My conclusion on the circuits power usage is that the junk batteries that I used for this application are not able to provide the maximum amount of current that the motor can use when spinning freely in the first test. And in the second test although the batteries performed nominally when free spinning, when the motor was jammed causing it to draw more current; the batteries failed to provide the needed current. So the batteries are the limiting factor here. Probably because they’re dying. From this slapdash test, I can tentatively conclude that if I wanted to add an additional motor, I’d also need to scale the power supply relatively … or use new batteries.

Really I should’ve tested it with two fresh 1.5 volt alkaline batteries as a control. Then I could’ve tested the motor, by adding an additional two fresh 1.5 volt batteries (in 3 volt series) parallel with the base two, to allow for a higher circuit current output without increasing voltage. That would’ve been a better test. But I took all the photos for this maybe two months prior to doing this write up on it; and I don’t feel like going back to it for something this minor. However, I will for the next article that uses this drag racer. This test was bad.

Closing thoughts.

Why make this thingy? (technical term)

I wanted to make a very basic bare-bones motorised toy car. The reason for this is that I think its a really good project to get a complete beginners feet wet in electronics, and more broadly in getting to actually making things in general. The scope of the project is small and its largely practical. There is very little in the way of actual measurements and maths. In addition, the tooling needed and materials used are basic and readily available, as they are salvaged cheap electronics and household sundries.

I think something like this is ideal for children especially since once they’re done, they end up with a toy they made themselves. Every time they play with it, they might get that little endorphin kick saying ‘I made that’ and before you know it — they’ve been bitten by the bug.

Another reason why a project like this is good is because unlike how many get a start in the general electronics hobby today – i.e. by purchasing kits and completing them. Creating something useful or of-value from junk promotes and develops a better skill-set then just putting together pre-made puzzles. Sure kits can develop people’s technical skills in doing so (like soldering), a familiarity for the various components involved, and even some trouble shooting and diagnostic abilities in order to get the thing that they put together actually working.

Usually though, in my experience once the kit is complete; be it an electronic dice, an AM radio, or what have you. It is done. At which point it is put down and forgotten. This is unless the person gets interested in one of the higher concepts the kit introduced them to; like in the case of how putting together a DIY radio kit can become a gateway to repairing radios or the ham radio hobby as a whole.

This is of course a good thing. However in general, purchasing kits has in my opinion limited returns (such as mentioned above), and can get overly consumeristic in nature. Buy the kit, make the kit, buy the next kit, make the next kit; and so forth. So what do you do when you don’t have the funds for the next kit, or have a child that becomes bored and thinks that’ll all this hobby has to offer.

Well that’s where one has to become inventive. Create your own kit. And from what? Whatever is around. Putting together machines of your own creation from junk develops imagination and creativity in people. It teaches them to see more than what an item is, instead it promotes seeing the parts it is made up of, and what it could become.

That old microwave the neighbour left out. Is actually not just worthless e-waste. It is actually a magneto, various high power resistors you can use as a resistive load in your experiments, and even a high voltage transformer that’s likely to get you killed. Obviously I am joking about the microwave, I am not advocating for inexperienced or immature people start with mains power electronics. Learn, but learn safely. I.e. Low voltage direct current devices.

Working with salvage also gives people very localised and consequently practical (read valuable) experience. This is because they’ll be working and tinkering with the local devices available to them. The same ones in their everyday environments, and in doing so they will gain insights into their workings. Insights that may lead them to modifying and repairing some of the same items for future fun and profit.

Note: I read over this, and even I can tell it’s pretty bloody preachy. I am not saying kits are bad, they are just another avenue for this hobby. Sometimes it’s nice to play with something that isn’t already broken. However I do think that (certainly basic) kits are transitionary. You make kits then you move on to fucking about with whatever takes your personal interest. And like I stated, kits are often a gateway drug to your chosen field.

Make no mistake what you are reading is the toned down version. The first draft was hard for even me to read without rolling my eyes in my skull. No need to thank me for sparing you that, but you are most welcome.

Thanks for reading.