EERef: Wrapping it up

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The Electronics Engineering Reference program is a personal project that started back in March of 2014. Over the weeks, it expanded with the addition of new topics, calculators, and tutorials, and the Quiz Center. It also went through major design changes that changed both the color scheme and layout of the program.

This project, like all of my projects so far, have been for fun. I take on these different projects to experiment with things I already know and to keep learning more. I’ve learned a lot from this project in both design and function and so I think it’s time to move on. I still have a list of things I would have liked to add to the program, but with pretty low public usage, I don’t have much motivation to continue. With that, the version now available (2.1.0.1) is the final build, unless something comes up. You can make requests for features by commenting on this blog post that could maybe possibly reopen this project.

Thank you for using EERef.

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EERef Version 2.1 now available!

I think I’m rushing updates too much so I think I’m going to take a break from EERef…

Anyways, I’ve added two new tabs: Arduino and Pinouts. They’re both reference material that I think is handy to have for quick offline access. I tried to make it so that you get the information you most likely need without having to scroll through pages of a datasheet.

The other “new” thing is that there will be an update notification when the program starts if there is an update available. It’s a little more aggressive now because I feel it’s more important to get updates out with the new pinout material. (Yes, I know people don’t care much about this program to even think it has something like update notifications, but let me play a little.)

Get it now!

 

EERef Version 2.0 now available!

compareI am happy to announce a major update release of my Electronics Engineering Reference Windows program! The past few minor updates have been focused on the design but I felt like I was going in the wrong direction. Version 2 is a shift to a completely new design and layout. It’s a lot more polished this time around.

new1Each section now has a dedicated window with everything, including the tutorials. Pretty much everything is contained in the main program window so there’s no reason to open a bunch of other smaller windows. Removing those windows actually shaved off a third of the program’s file size.

The new design allows for the program window to be resized and maximized. There are just a couple sections that will stretch with it, but the ones that don’t really don’t need to.
new2I was going for that “flat” UI that’s trending these days. There’s a lot of Segoe UI font in there so hopefully you have it installed on your PC.

Besides the new design, a new feature is the Essential Formulas section which is just a quick reference to basic formulas. I hope to continue building on it to make it larger and to include calculators. I also fixed a bug in the number systems calculator that told you there was an overflow error if the result was 1.

Download it now!

EERef: Update 2 (Releasing Friday!)

Since the last update, some great things have happened. I’m excited to share some good news!

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I put up a website for this project. I’m in a love-hate relationship with WordPress because there’s not much I can do with the themes. I’ll still put up a project page on this blog eventually, but I’m focused on the Google Drive site because it actually plays a role in the program.

The Visual Basic program will connect to a page hosted on Google Drive that will pass it information. This allows me to push update information to the Visual Basic program on your computer. It doesn’t actually push the information, though, you have to check for updates manually. This is the only thing in the program that needs an internet connection.

If you look at the website I linked earlier, you will see the program features. All of the features listed there are complete at this point, and they are all of the features I wanted to have as part of the initial launch. I still have plans for more content so that’s why having a way to send update information was important to me. There will be update posts here and on my Google+ page.

With all of that said, the initial release will be this Friday! From now ’til then, I’ll just be testing the program and going over the content for mistakes. I also need to decide the version number. I don’t think it’ll be 1.0.

Thanks for visiting! I hope you’ll give it a try on Friday!

Tutorial: Full-Wave Rectifiers

IMG_0747In my first tutorial about power supplies, I mentioned I picked up this adapter by accident. This adapter has an AC output which is pretty useless to me, unless I build a rectifier for it. That’s what this second tutorial is going to be about.

I was taught about rectifiers by this guy who just threw up a whiteboard of equations every lecture. The labs didn’t help because they were boring (ie. Get the circuit working, get a signature, go home, wonder what I’m doing with my life). While I sort of understood what was going on, I definitely needed some time to register it all, even if that time is like two years later. Looking up information online to refresh my memory was difficult because it was the same formulas being thrown back at me.

In this tutorial, I’m going to show you how a full-wave rectifier works. It changes an AC signal into a DC voltage. My goal with this tutorial is to explain how it works with little to no formulas, enough so that you could practically use everything here if you happened to be stuck with an AC output adapter like me.

ewb_posWhenever you’re analyzing a schematic, the best thing to do is group components into blocks and figure out what they do, and then see how they work together. This is what the first piece of the rectifier looks like. When the sinusoidal input is above the x axis (positive values), the current takes the path of the red line starting from the top of the source (the circle). For now, think of the two dots as the places where you’d put your oscilloscope probes to see what’s happening.

ewb_negWhen the source voltage is below the x axis, you can think of the source as flipped upside down so that current is now coming out of the bottom of the source and following the blue lines. Notice how the flow of the current is going through your top oscilloscope probe and exiting the bottom again as it did in the previous diagram.

ewb1This is what the waveform now looks like with the AC source going through that diode configuration. The negative values of the sine wave is flipped over the x axis so all of the values of the signal are positive.ewb2When you add in a capacitor, the capacitor charges once the input signal is applied and then stays at a certain voltage (the voltage level will be discussed later). Since there is no load, it doesn’t discharge so the voltage remains a nice DC output. Obviously, this is useless to us, but it shows the reason for the capacitor.ewb3Once a load is added (the resistor in the diagram), you start to see ripples in the voltage. The peak-to-peak value of the ripple is known as the ripple voltage. This ripple happens because the capacitor discharges as the input signal heads toward zero. The capacitor charges again as the signal heads back toward its peak.

The reason I did the simulation is because I don’t have an oscilloscope. I still did it on a breadboard with my multimeter in hand, where I did a couple simple calculations. Let’s go through it.

IMG_0792The source measurement is giving us 14Vac…IMG_0793… at 60Hz.

The 14Vac that we’re seeing is an RMS, or root mean square, value. Any value taken by a multimeter is an RMS value. All you need to know is that if you are given an RMS value, the peak is actually the RMS value multiplied by √2. To go the other way if you are given the peak value, the RMS value is the peak voltage divided by √2. If you’re unsure what to do with √2, just remember that the RMS value is always less than the peak.

IMG_0794 So, with our 14 volts read by the multimeter, the peak is actually 19.8v. If we account for the two diodes that are conducting for each half of the cycle, that’s a 1.4v drop (each diode is a 0.7v drop). That leaves us with an 18.4v output. How satisfying. Remember that we have to use the peak value because the capacitor charges up the peak, not the RMS level (which is 70.7% of the peak).IMG_0795And obviously, with a DC output, the signal is 0Hz.

IMG_079618.4 volts is still pretty high for the applications I have for my supplies. The LM7805 voltage regulator can handle input voltages between 7-35 volts to produce a 5 volt output. You can use other voltage regulators to have other DC levels for your projects.IMG_0798For an example of a practical use, here’s the rectifier and 5v regulator driving one of my new blue LEDs.

So that’s it! Hopefully you understood everything in this tutorial. While I probably wouldn’t use this in a project (for space issues, primarily), it’s good to understand this concept as it is basically what’s going on in some DC output adapters.