Electronics Hobby

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pbgben

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#142646 19-Mar-2014 17:20

Hello,

I'd like to get started with electronics. I have ordered a solder station and an Arduino Starter Kit to get me started, is there anything else you'd recommend me getting or any specific projects that are good to teach the basics?

I'm a Web Developer, so know HTML, CSS, PHP etc. So Im not to worried about learning the language.

Eventually Id like to turn an old lawnmower into an autonomous "Lazy mans mower" kinda thing.

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#1009248 19-Mar-2014 19:05

A couple of decades ago Dick Smith were a great place for electronics hobbyists ... these days Dick Smith is mostly just another appliance store, but the bigger branches do still have a few bits and pieces (usually at the back) which may include some project sets, although often aimed at kids.

I think Jaycar may be the best (if not ony) chain for electronics hobbyists these days.

pbgben: Eventually Id like to turn an old lawnmower into an autonomous "Lazy mans mower" kinda thing.

I guess it's good to have "small" first ambitons. ;-)

Probably easier and cheaper to simply buy a sturdy peg and rope - stick the peg in the ground, tie the rope between the peg and the lawnmower, and then let the lawnmower just wind itself in in smaller and smaller circles.

OR just buy a robo-mower.

Aredwood

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#1009499 20-Mar-2014 00:50

Recommend buying a semi decent multimeter. Something like http://www.jaycar.co.nz/productView.asp?ID=QM1323 Since this multimeter is CATIII rated you can safely use it to measure Mains voltages. (But don't recommend you doing anything with mains as a beginner).

It will do almost everything you are likely to need. At least as a beginner.

Grab some old circuit boards and bits of wire. And practice soldering.

Then have a look through the kits section of the Jaycar catalogue. Go into a store and grab a copy of their printed catalogue. I find it much easier to use than their website.

Have a look at the kits section. Buy 1 of the simple kits that does something useful / interesting for you. And build it. The instructions that come with the kits explain how the circuit works as well as how to build it. therefore they are good at teaching basic electronic theory.

Also you will need a power supply for your circuits. For this get a computer ATX powersupply. (Since everyone either has or knows someone with some old desktop computers). Connect the PS_ON wire (usually green) to ground to make the power supply switch on without it being plugged into a computer. This will give you +12V +5V +3.3V -12V and +5V standby. The ATX computer power supply standard includes over voltage, undervoltage, and short circuit protection. Therefore they are great for using to power your projects. And if you manage to destroy one you can get some more almost for free. They are also good for opening up and stripping parts out of. They have lots of useful general electronic components inside. They are also perfect for integrating to arduino projects. Use the +5V standby output to power your arduino board. Connect the PS_ON wire to one of the arduino's I/O pins. Set the pin as an output. And then you have software control of the power supply. When your code sets the pin to 0 the supply will be on, Set it to 1 and it will be off.

You ideally need to learn both analogue electronics and the arduino. No good knowing how to code if you cant interface to the outside world.

sleemanj

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#1009816 20-Mar-2014 13:13

pbgben:
Eventually Id like to turn an old lawnmower into an autonomous "Lazy mans mower" kinda thing.

Well you're on the right track, you have a itch, and an idea of making something to scratch it.

Like any good development, start with small things, work up to scale proofs of concept, and then move onto full scale.

1. Blink an LED - you will learn how to writing digital logic to the real world.
2. PWM that LED - you are going to need to control the speed of various motors, this will teach you how.
3. Drive an LED with a transistor, and also a mosfet - you're going to have to learn about transistors and mosfets
4. Drive a DC motor with a transistor, and a mosfet in one direction - now you're getting somewhere, you'll learn about inductive kickback and flyback diodes, to save yourself some burnt out components.
5. Drive a DC motor with an H-bridge configuration (start with an IC like the L293D, and move to making your own out of discrete components) in both directions, now drive 2 motors in both directions - now you have the pieces in place for a small scale crude, blind, self-driving platform

From there, you need to look at sensors to know where you are and where you're going, communications so you can get messages to it (like "stop you're about to run over a kid"), scaling up the motors and necessary control to handle the high current, maybe using different motors such as steppers or brushless, all the additional code to control everything....

There's a few good places on the net you should get yourself acquainted with:
EEVBlog.com (particularly the forums, and Dave's videos at Youtube)
dangerousprotoypes.com
hackaday.com
adafruit.com
sparkfun.com

---
James Sleeman
I sell lots of stuff for electronic enthusiasts...

pbgben

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#1009845 20-Mar-2014 13:30

Thanks for the support :)

I'v seen one of the EEV Blog videos before, I had forgotten about him :/
Ill filter through the forum when I get stuck.

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jonb

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#1009847 20-Mar-2014 13:32

As you are in Auckland you could go along to Tangleball on a Tuesday and have a chat and a tinker

pbgben

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#1010203 20-Mar-2014 21:43

Tangleball sounds good, I'll think about it.

My solder station arrived today. I know its Chinese but its an OK start.

https://imgur.com/a/5XYiR

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richms

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#1010249 20-Mar-2014 22:35

Adafruit tutorials are great as are their products. Postage is a killer tho.

Freetronics stuff is at jaycar for ok prices. Ebay for cheap stuff but I would recommend starting with a real arduino incase you need to post photos of your wiring to avoid all the forum whiners about supporting the clone market.

Richard rich.ms

Mark

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#1010367 21-Mar-2014 06:32

Aredwood:

Also you will need a power supply for your circuits. For this get a computer ATX powersupply. (Since everyone either has or knows someone with some old desktop computers). Connect the PS_ON wire (usually green) to ground to make the power supply switch on without it being plugged into a computer. This will give you +12V +5V +3.3V -12V and +5V standby. The ATX computer power supply standard includes over voltage, undervoltage, and short circuit protection. Therefore they are great for using to power your projects. And if you manage to destroy one you can get some more almost for free. They are also good for opening up and stripping parts out of. They have lots of useful general electronic components inside. They are also perfect for integrating to arduino projects. Use the +5V standby output to power your arduino board. Connect the PS_ON wire to one of the arduino's I/O pins. Set the pin as an output. And then you have software control of the power supply. When your code sets the pin to 0 the supply will be on, Set it to 1 and it will be off.

You ideally need to learn both analogue electronics and the arduino. No good knowing how to code if you cant interface to the outside world.

Sorry, but that has to be the worst advise I've ever seen anyone give a beginner in electronics! Use a PC power supply outside of a case ? Oh and just solder a wire to ground so you can turn it on in a way it was not designed to do ??

Please DO NOT re-use a PC power supply as your bench top power, do a google for "Can a PC powers supply kill you?" and you'll see lots reasons why it's a dumb thing to do.
I've some nice electrical scars on one hand from trying to move a PC power supply out of the way that someone had left on a desk at work (me being naive in just moving it without checking where the plug went) ... I could't let go of the thing once I put my hands around it, it's really not comfortable to feel all the muscles in your upper body lock up, and you actually can hear that buzzing noise they use in the movies when someone is being electrocuted.

If you want to play with electronics you should look at getting one of these (again Google) :

http://nz.mouser.com/Power/Bench-Top-Power-Supplies/_/N-wp4b

Have fun!

sleemanj

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#1010496 21-Mar-2014 11:26

Mark:

Sorry, but that has to be the worst advise I've ever seen anyone give a beginner in electronics! Use a PC power supply outside of a case ? Oh and just solder a wire to ground so you can turn it on in a way it was not designed to do ??

While it's true that an ATX supply can supply a LOT of current, and that it has no limiting ability, and that a proper current limited supply is better, and that for most people playing with small electronics some batteries and an adjustable regulator or DC-DC converter is what they need, you are way alarmist on the "dangers" of an ATX supply.

ATX power supplies are strongly encased and unless somebody has intentionally modified, that case is earthed. There is no "using it outside of a case" needed.

Grounding PS_On, which is one of the wires on the ATX connector is exactly what your motherboard does to turn on the PSU, that's exactly "how it was designed to do".

Mark: I could't let go of the thing once I put my hands around it,

You do know that when installed in your PC, the PSU case and your entire PC case are electrically connected right. Do you fret over touching your PC case when it's switched on?

The PSU in your case was faulty because mains active had become present on the case AND somebody had modified it internally to crudely float it (earth disconnected) which is neither necessary nor recommended. That or your building needs a serious investigation into it's electrical system.

---
James Sleeman
I sell lots of stuff for electronic enthusiasts...

richms

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#1010502 21-Mar-2014 11:34

Ask your work why they allowed a non certified person to be testing a pc PSU in a non controlled environment 90 a circuit lacking basic rcd protection.

Pc power supplies are big brutes and you don't want to connect possibly miss wired breadboarded circuits to one.

There are really cheap constant current/voltage switchmode circuit boards on ebay which will make it into something safe with a current limit. Add one of those to an old atx PSU and you are good to go. I have a headache so am in bed on the phone so it's hard to look for them but will post something later.

Richard rich.ms

ubergeeknz

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#1010505 21-Mar-2014 11:39

Indeed, an ATX power supply, assuming it is not faulty and remains inside of the metal case, is quite safe. 12v is very unlikely to hurt you in any way. Worst case you short an output and it blows a fuse/component. I'd suggest getting a molex socket and wiring it to some banana plugs or something.

But a current limited supply isn't a bad idea, since you might be able to not fry something if you made a mistake. You can easily build a current limiter good enough for the purposes of small electronics using an LM317 and a handful of other components.

Edit: using a small wall wart as suggested above, is also a pretty good idea. You don't need a whole lot of current for this stuff. Even a 9v battery will do it in most cases :)

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pbgben

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#1010508 21-Mar-2014 11:45

I think I will go the ATX route, they are super cheep to get and It would be a good project.

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pbgben

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#1010512 21-Mar-2014 11:50

Something like this?

http://www.jordandsp.com/ATX-bench-top-power-supply-adapter.php

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richms

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#1010523 21-Mar-2014 12:06

That's just a fancy board that breaks the cables out. Plenty of other designs do that for less.

Richard rich.ms

Mark

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#1010524 21-Mar-2014 12:09

Well good luck with that .. personally I think it's stupid to recommend to an electronics newbie to go and start playing with a PC power supply, and I just hope that the people behind the usernames saying it's OK don't ever do any work for me.

While you are at it, under your sink there are all sorts of chemicals, why not go mix them up and see what happens, I'm sure it'll be just fine!

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