SparkFun will be closing early at 3:30 Friday 5/27 and remain closed Monday for Memorial Day (5/30). Orders placed after 2pm MT on Friday (5/27) will process and ship out on Tuesday (5/31).


Member Since: February 5, 2013

Country: United States

  • I like how the conductor is using a screwdriver as a baton - I assume that’s the technology class teacher?

  • You could split the hot and neutral wires (not ground!) and it will work. But working is not the same thing as being safe. There are a couple ways it can be done safely, and many ways that are not safe, all of which still “work.” The safest way may be to split the hot line power before the relay: one branch goes to the relay and the switched outlet, the other goes to an unswitched outlet where you plug in your power supply. But see Member #415973’s comment above about the dangers of having high voltage splices and low voltage wires in the same box.

    Iif you have to ask that question on a forum like this, I would guess you don’t have much experience with working on line voltage AC power, and I would recommend that you not try it.

  • Actually, if we are trying to be correct, a GFCI can help prevent you from getting a shock, that’s one of its major purposes. If you touch the hot wire, current will tend to flow through you to ground if possible: this current is a ground fault, and that current will cause an imbalance between the hot and neutral wires that are being monitored by the GFCI, and the current will be interrupted. This is the most common electrocution mechanism that may happen when you grab a hair dryer with wet hands, stick a knife or fork into a toaster to free jammed bread, etc.

    But it won’t protect you from a shock in the less common situation where you are completely isolated from ground, and you touch both the hot and neutral wires - in that case the current flowing through you is going back through the neutral line, so there is no imbalance. The rest of what you say is correct: the GFCI does not protect against overcurrent situations.

  • Not only is there a delay from when you press the key to when the pipe starts sounding, but that delay is different depending on the note - high notes with small pipes react faster than low notes with large pipes. So that delay is constantly varying as the organist goes up and down the scales. A big pipe organ looks like a complicated instrument at first glance, but it gets much more complicated when start looking at the details. Mastering a large pipe organ is truly an accomplishment!

  • You’ve probably figured it out by now, but just in case, try this:

    value = scale.getGram();
    Serial.println(value, 1);

    The “, 1” part is an extra parameter for the Serial.println() function call, which tells it how many decimal places to print when printing floating point numbers. It has nothing to do with the scale.getGram() call.

  • Great explanation of impedance and reactance! I wish my EE prof from almost 40 years ago was as entertaining and would’ve explained it as well as you. If he did, I might not have changed majors and might have stayed in EE. Even though it’s not new material for me, I did learn something and have a better understanding of it now. Thank you!

  • I was part of last year’s feeding frenzy, and not part of this year’s sale. The main reason: last year you could back-order, but not this year. half of what I ordered last year was back-ordered.

    I didn’t wait up until 3:00 am my time to get to the sale, but I did check it out in the morning when I got up. Just about everything I was interested in was already sold out, so I couldn’t order them. A couple mildly interesting “throw-in” things were still available, but their savings were only a couple dollars total, so it wasn’t worth placing an order just for them – I’ll throw them in when I make the next order.

    Curiously, I seem to remember a lot more things being sold out on Saturday than there are now. Maybe I’m imagining things, but I’m sure I’m not completely crazy: the post-mortem shows the Uno R3 SMD selling out in the first hour. But now here it is the next (business) day, and it shows 199 in stock? What’s up with that? Given the rate they were selling at, I’ll bet those 199 would’ve been gone had they been available.

  • I just stumbled upon this tutorial. Nice write-up! I want to thank you for it, because it just helped me out. I’ve been working on a project, which has fallen to the back burner, primarily due to analysis paralysis. I was trying to come up with one large board that could do everything for the project, but kept getting hung up on the details: how many optically isolated inputs do I need? How many outputs? How many analog inputs? What other special I/O will I need? My plan is to make several of these systems, and distribute them in various locations, all collecting data and controlling equipment and reporting back to a central location.

    Well, the problem was that different locations needed different combinations of I/O, and the board was quickly growing out of hand: one location needed lots of inputs, another needed lots of outputs, another needed more analog, etc. No location needed the maximum amount of everything, so there would be plenty of wasted resources if everything was on one big board.

    First lesson learned from this post? Use a stack of simpler shields. Therefore, only the required functions are installed at any one location, with minimal wasted resources. One place needs extra inputs? Stack a second addressable shield onto it. Another place doesn’t need analog inputs? Don’t add the analog shield.

    Next lesson? Use polarized connectors. At one point, I was going to put a row of screw terminals along one edge of the board. What a pain that would’ve been to replace the board if (no, WHEN!) needed.

    I appreciate several other lessons learned from this write-up, but I don’t think I have to list them all. Just know that I appreciate the post, and will take it to heart! My project is back on track. Thank you!

  • Oh, don’t get me wrong, I think it’s great that we have so much information available online, and so many online sources for more parts than I ever imagined were available back in the ride-the-bike-to-Radio-Shack days. Finding datasheets online and downloading them into a tablet makes it much easier to find the information you need. But there are still fond memories of being able to walk into any Radio Shack for a good selection of parts, and also flipping through a well-worn 7400 series databook.

  • Wow, this brings back memories! As a kid, I remember how excited I was when I was finally allowed to cross the the busy road a few blocks from the house, all by myself – it meant I could ride my bike to Radio Shack any time I wanted! It was only about 6 blocks away and I went there often. It was interesting seeing all of the fancy equipment on the shelves, but I always went straight to the back of the store where there was rack upon rack of parts – almost half the store, not the small cabinet of drawers they have now. You could get just about anything back then: I built many complete projects with nothing but Radio Shack components. And browsing through the catalog – man, I couldn’t wait until a new catalog came out: looking through it was almost like porn to a young budding engineer nerdling. And I don’t know how many wonderful hours I spent building all manner of projects with the 100 in 1 kit.

    In recent years, it’s been so depressing going into a Radio Shack. I remember when the guy behind the counter actually new something about electronics, and could actually help with problems and give advice on projects. At the time, their motto really made sense: “You’ve got questions? We’ve got answers!” Now, the motto might as well be “You’ve got questions? ummm… We’ve got cell phones!”

    It will be sad to see them go. But as it was said in the opening lines of this blog: in my mind, they died years ago. :-(

    PS: I also really miss HeathKit..

No public wish lists :(