Buy Components With Care

Another thing I learned is to ignore, at least partly, all the videos that say go out and get a few basic parts.

Actually the advice is sound but incomplete.

You really need to have at least some idea of what to look for when selecting / buying components and it helps to have at least a broad idea of what you think you’ll be doing with them. For example if you are going to use a 12 volt power supply, you can’t go running 12 volts through parts rated for 3 volts (ie most leds).

You can easily step the voltage down with resistors but to do that you absolutely have to know two things:

    1. Ohms law – sorry but it cannot be avoided so if you can’t understand ohms law, you’re pretty much screwed. However it is is fairly simple arithmetic and there are some free online calculators available. However one way or another, you’re going to have to learn a few basic laws such as this one.
    2. You need to know the voltage capacity of every component (aka forward voltage) and the current rating too (amperage aka amps). Do not buy anything where these values are not given by the seller. Note that some components such as transistors & relays will have product codes that you can google.But the lesson is, don’t buy it before you can get specs for it and when you have it, keep it labelled and sorted in some way.


This relay has coding that you can look up. Google is your friend and an amazing resource for electronic information.

Relays have no way of identifying the power rating. The coloured bands identify the resistance (ohms) value only.

Early Lessons

Got some resistors today – first lesson learned. Do NOT buy blue resistors.

Resistors generally come in blue or beige. To read a resistor’s value you have to decode the coloured bands on its body. The blue makes it hard to easily distinguish colour bands.

This is actually a good picture and it’s not too hard to tell the difference. But in real life some of these things are 2mm long and less than 1.5mm thick.

Try telling them apart then!

So lesson 1 – avoid blue resistors.