A basic guide to sourcing and pricing various components from local and international suppliers.
By David Hedger.
Sourcing components is an often underestimated part of the engineering design process. You can easily spend an entire day or more tracking down just a few parts that need to fit very specific criteria. The aim of this guide is to let you know, as QUT students, what your options are, and what I’ve found in my experience as an engineering undergraduate.
One thing that every student trips up on at some point in their career is lead times. If you are presenting your device tomorrow, and you break something the night before, your options become extremely limited. You may find a physical shop somewhere that sells exactly what you need, but expect to pay far more than you would online for the privilege.
Essentially, lead times and price tend to be inversely correlated. If you buy something direct from China, it will cost a fraction of what you’d get it for in a store, but it could take months to get here instead of being in your hands this afternoon. There are exceptions to this rule, especially if you buy in bulk, but for most small projects you won’t have that luxury.
Another thing to look out for is the difference between shipping time and delivery time. You may have paid for DHL Overnight Super Express or whatever, but that only matters if the store actually gives the box to DHL on the same day. If you have a 1-7 day shipping time and a 3-7 day delivery time then the safe assumption is to add those two numbers together.
The last thing you want is only doing proper testing a few weeks from the due date, and having a key module just burn out or prove inadequate under load. Keep your toolbox close and your lead times closer.
This is just a brief overview of a bunch of component and module suppliers. This section is almost entirely opinion and your experience may vary, so use this as a rough guide only.
Individual Electronic Components
When you’re looking for things like individual transistors or a particular integrated circuit, these guys are your friends. Individual components from these sites are often incredibly cheap, and are delivered with detailed tax invoices and shipping notes. They often service large industrial clients, so a lot of their pre-assembled products are focused towards that market. Don’t be scared off by extremely expensive power supplies and the like, they probably have industrial compliance requirements far above what you need in a simple robot.
Probably the best website of the bunch, relatively easy to navigate. Free overnight shipping on orders over $45. Average prices and range, but good enough for most purposes. Will happily split orders when some parts aren’t immediately available and ship them when they arrive.
Difficult to use website, but free overnight shipping for all orders. Great if you really need just one part really quick. Sub-par range and prices, but sometimes has a couple of really niche parts for some strange reason.
Has everything. If it’s not on Digikey it probably doesn’t exist. Website is average. Based in the US so longer lead times than most, but easily the best range and prices. Free shipping only on orders above $200 USD.
Roughly on par with Element14, but with a different range and a slightly worse site. Free shipping on orders over $60.
Sell some very good power and motor management modules that simplify things when you can’t be bothered making your own. A good source for reliable enough motors in a bunch of practical sizes. Not much in the way of a community, but usually very well documented. Based in the US, with the associated lead times.
Focus more on microcontroller style solutions. Data collection, Arduino shields, sensors, kits and LEDs. Very strong community with decent videos and tutorials. Most items have their schematics and layouts available to download. Also based in the US, so lead times.
These guys tend to make very flashy things. Adafruit are big on LEDs and wearable tech, but they also do quite a fair bit of motor control and software on the side. Really good tutorials on their products and also various electronic topics. Again, US, lead times.
LittleBird Electronics, Core Electronics, Robot Gear
These guys are basically Australian resellers for Pololu, Sparkfun and Adafruit. They don’t seem to produce anything of their own, but they have local stock, so they can have much shorter lead times. They also stock some parts from a whole range of other smaller manufacturers.
Having a local physical store like Jaycar is great, because you can drop in and have a look at things before you purchase. Of course the other advantage is being able to purchase things the same day you want them. They have an ok range, and their staff are usually helpful and knowledgeable, but are generally more expensive than online stores. If you can afford the lead time, it is often cheaper to use one of the above online suppliers first, but it can also be useful to go in to the store and physically see some of the components and how they fit together.