If you design your own electronics circuits you have to select the best parts for your design. This can be very time consuming especially if you do not know where to look for them. For me problem parts are electromechanical parts, connectors, push-buttons, that sort of thing. What I do in those cases is look through a component distributor catalog and see if I can find something to my likes. Unfortunately these catalogs no longer reflect very well the full offering of the distributor’s products as they prefer to present them on-line.
On-line component browsing on a distributor site just is not very practical. When Digikey decided to stop distributing their paper catalog we did a little reader’s survey of which the outcome was unanimous: No!!!
If you do a search on a part you will get many useless results, but you will also miss many because the search engine didn’t find them. Typical is the table refinement option where you can tick the specifications you want. You cannot simply tick one because often the same specification is listed several times with different wording so you have to tick ‘em all. Also ticking an option will remove the parts for which this particular parameter was not specified in the first place. “Number of ways” or “polarity” can mean the same thing for a switch, but the filter only knows one of them. Voltage regulators are one example of hard to select parts. Input voltage range, output voltage range, type, etc. all parameters that can be (and are) specified in different ways making them difficult to compare.
RS Components just launched their new improved website where they put a lot of effort in improving the search engine. They told me that they now remove much more irrelevant results and they return harder to find results, but they didn’t say anything about addressing the issue of parameter homogeneity.
So is it any better now? Let’s try to pick a low-dropout voltage regulator. The RS website returns 58 results (September 30, 2011, 14:00 h CET). Filtering on “Input Voltage” only shows 19 possibilities; strange, what happened to the other 39 parts? They have no specified input voltage? I find that hard to believe for a voltage regulator.
There are three parts with an input voltage range from -1 to 40V that turn out to be three versions of the same device (UC3836/2836 from TI). There is only one device with a range of 3.5 to 36V (LTC1624 from Linear Technology) but it is not the same as the TI one although the input voltage range is inside the -1 to 40V range, so the TI part would be an option too.
The filter proposes four devices with an input voltage of 40V without a minimum value. The result is again four similar devices, again from TI, but this time the UC3834/2834. Looking up the device on the TI website I discover that TI specifies an input voltage range of 5 to 35V for this device, not 40V. So what do they specify for the UC3836 on its product page? 6 to 40V! Eh? But RS said -1 to 40V, right? Yes, but actually that is the absolute maximum range. Duh! In that case, why didn’t they use -0.3 to 36V for the LTC1624? Pears and apples, that’s what this is.
Now you may think that I spend a day or so on finding this example, but no, I didn’t. I found it while typing up this post. It was that easy, meaning that it is the same for other parts. It is still very hard to use a distributor’s website for selecting parts for a design. The new RS site does look slicker and maybe the search engine is better, but I am not sure if I will notice the difference.
BTW, did I mention that the filter button doesn’t work in Firefox? I suppose (for now) that’s just my Firefox being incorrectly set up.
Friday, September 30, 2011
Open World Forum 2011
Saturday 24 September I joined two of my colleagues at the Experiment Day of the Open World Forum in Paris. Since it took place not far from the Crazy Horse I had no difficulties in finding the venue. My colleagues had come the day before by car because they had to bring books and magazines and especially the OSPV1, our open-source auto-balancing two-wheeled vehicle that we were to present.
The OSPV1 self balancing vehicle
The Forum was held in a rather high-class venue that had been paid for by a very impressive collection of sponsors in one of those rich “quartiers” of Paris where you get more easily run over by a Ferrari then by a Peugeot. The Open World Forum is all about Open Source; here the first question people ask you about a product is what license it is released under. I tend to associate Open Source with financially impaired people (i.e. students) with beards and spectacles hacking away in poorly furnished rooms and so it seems strange to actually meet these people (who came indeed pretty close to how I always had imagined them) in such a high-end place. Free lunch & drinks for everybody, all you can eat sushi in the pressroom, a real “we don’t care about money we only care about Open Source” attitude.
The ambiance was quite arty and inspiring with many great projects being showed off. It was interesting to meet so many people working with electronics without having a formal electronics education. They simply define an objective and then see what they can do with plug ‘n’ play electronics like Arduino to achieve it. These are electronics users (or should I say consumers) that embed ready-made building blocks in their projects.
I was a bit disappointed by the number of visitors. For some reason too few interested people made it on this sunny day to avenue George V. Maybe they didn’t have the money for a metro ticket? Make sure you visit next time, it is definitely worth skipping a lunch to save some money to pay for the trip.
The Forum was held in a rather high-class venue that had been paid for by a very impressive collection of sponsors in one of those rich “quartiers” of Paris where you get more easily run over by a Ferrari then by a Peugeot. The Open World Forum is all about Open Source; here the first question people ask you about a product is what license it is released under. I tend to associate Open Source with financially impaired people (i.e. students) with beards and spectacles hacking away in poorly furnished rooms and so it seems strange to actually meet these people (who came indeed pretty close to how I always had imagined them) in such a high-end place. Free lunch & drinks for everybody, all you can eat sushi in the pressroom, a real “we don’t care about money we only care about Open Source” attitude.
The ambiance was quite arty and inspiring with many great projects being showed off. It was interesting to meet so many people working with electronics without having a formal electronics education. They simply define an objective and then see what they can do with plug ‘n’ play electronics like Arduino to achieve it. These are electronics users (or should I say consumers) that embed ready-made building blocks in their projects.
I was a bit disappointed by the number of visitors. For some reason too few interested people made it on this sunny day to avenue George V. Maybe they didn’t have the money for a metro ticket? Make sure you visit next time, it is definitely worth skipping a lunch to save some money to pay for the trip.
Subscribe to:
Posts (Atom)
