Cool Cap Engineer

Engineering by an anime nerd


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Rants: Lab Update #2

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I never thought I will post another lab update so quickly.  Not only did I reorganized my lab, but I recently got a plethora of new parts and one new test equipment that I would like to talk about today.

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Some new goodies thanks to my co-worker

So first, I would like to talk about some more discrete parts I obtained from one of my co-workers. Of course I got a bag filled with resistors, npn transistors, and pnp transistors, but I never expected to get two bags of 10uF wet-tantulum through-hole capacitors. Keep in mind, through hole wet-tantalum capacitors are bloody expensive, and I got them for free! I also received two 3M connectors, which are ideal for debugging through-hole ics without breaking a connection to do so.

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My new Tektronix oscilloscope! A little old, but still, a Tektronix oscilloscope!


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Rants: Second Room, New Lab

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Back in March, I moved from Kingston NY to Lawrence/Andover MA to work as a design engineer for a power electronics company. Due to the fact I needed to find an apartment within a 3 week time frame, I had no other choice but to rent a two bedroom apartment, even though I will be the only one living in the apartment. So, what did I do with the extra room? I turned it into a lab! Although I still need to get a bench multimeter, hot air soldering iron, etc, I think it’s a good starting point. Anyway, here’s a small tour of my lab.

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So right now my inventory is pretty sparse. The cabinet on the bottom I had before I moved to MA and contains spare items.Some of the items include diodes, op amps, atmel and PIC18F  microcontrollers, PIC programmers, and AVR programmers. However, one of my co-workers gave me his old electronics cabinet. This one contained a diverse amount of through-hole discrete parts such as resistors, capacitors, even some inductors. Either way, I will not run out of discrete components anytime soon.

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So I obtained another goodie from my co-worker- a power supply (15V/1A). Although I do not use it often since I have a higher wattage power supply (32V/5A),  I’ll find a use for it soon. For the first time in my engineering career, I finally invested in a….meh function generator. I never heard of Victor before obtaining the function generator, but it does a decent job. My chief complaint is the minimum and maximum duty cycles for square waves. This function generator can only be set to have a 20%-80% duty cycle for square waves. As a person who likes to switching things at a fast pace, this continues to annoy me.

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One of my electrical engineering colleague told me that a good electrical engineer typically has an analog and digital oscilloscope. I took that advice to heart and obtained an old school analog oscilloscope from – you guess it – my current co-worker. I’m not going to lie, I’m still tying to figure out how to use this scope. I tried looking for the instruction manual online and even asked my co-worker who lend me the oscilloscope, and I still cannot figure out how to use it.

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So this is one of the supplies I brought while I was living in Kingston. As embarrassing as it sounds, I lost the caps to the power supply’s output during the move to MA. For now, I have alligator clips attached to the power supply’s output. Although the current capability of the cables is a little less that the maximum current the power supply can deliver, my current projects are not really current demanding, so I can get away with it. Of course, I cannot forget my multimeter from Radioshack, Although I was groomed to love Fluke multimeters, I cannot complain about it as it gets the job done. I will get a bench and Fluke multimeter sometime in the future.

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So here’s my current oscilloscope. Originally I wanted to get a small cheap Techtronix oscilloscope but apparently the cheapest Techtronix oscilloscope I could find at the time was $1000. So…I brought a Hantek oscilloscope from Ebay. Although I find the screen to be a little hard on the eyes and the speed isn’t something to brag about,I can save pictures using USB! I cannot tell how many oscilloscopes I used in the past could only save waveforms using a floppy drive. I know it’s petty, but after using oscilloscopes for two years  now, it’s kind of a big deal.

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So the last item I got for my lab is my new soldering iron. My previous soldering iron I obtained from Radioshack started to affect my soldering. Instead of getting another cheap crappy soldering iron, I decided to invest in a Hakko 936 soldering iron. Not only did I get a new soldering iron, but I got two chisel tips with them. What’s great about these chisel tips is that the heat is spread out a little more, making through hole soldering a little easier.

So that’s it for my little post for today. Again, I apologize for the delay, but assimilating to life in MA was….more time consuming that I thought. Anyway, thanks for reading this post and if you have any suggestions on any lab equipment I should get, then please comment below! I will see you guys next week and have a wonderful day!


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Analog Discovery: An Electrical Engineer’s Best Friend

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If there’s anything I learned in college, then it is this: you cannot solve a circuit related problem without having the proper debugging tools to do so.  There were numerous times in which I could not solve any problems in my circuit because I could not properly see a waveform, or could not measure the current correctly.  Then in my last semester of senior year, one of my professors gave to me Digilent’s Analog Discovery for free (I got a lot of free stuff during college).  After obtaining that piece of engineering beauty from my professor, I instantly fell in love with the device.

What is the Analog Discovery?

The Analog Discovery is a USB multitool to properly debug or power your circuit.  This little device has an oscilloscope, function generator, DC power supply, digital outputs, and logic analyzer in one package.  All you need to use the device is a computer with a good ole’ USB connection.  So what tools are available? I’ll talk about the tools I used on the Analog Discovery thus far.

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1) Oscilloscope: You will find yourself working with signals that will not always output a simple square pulse. Sometimes, you’ll work with sinusoidal, triangular, and even sawtooth waveforms. To make sure the circuit is outputing the correct waveform, you need to see it. This is where an oscilloscope comes in. Although I saw waveforms moving at 1KHZ (as seen in my implementing PWM on PIC18F tutorial), the fastest signal you can see on the scope is 5MHZ.

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2) Multimeter:  Although most electrical engineers should have at least a multimeter in their possession, the Analog Discovery includes a multimeter as well! Although the device claims it can measure up to 20V, I usually play it safe and measure up to 5V.

How do you use it?

Although I mentioned you need a USB micro cable, you also need to download Waveforms from Digilent’s website.  Underneath the Analog Discovery is a bunch of wires. Based on what tool you want to use, you’ll need to use a specified  wire. For example, if I wanted to use the tool’s oscilloscope, you need to connect Analog Discovery’s 1+ to your signal, and 1- to ground. Finally, if I wanted to use the 5V DC power supply, then I’ll connect my devices requiring 5V to V+ and my devices requiring ground to V-. If you want a more concrete look at Analog Discovery’s pinout diagram, then look at the picture below, which can also be found on Digilent’s website.

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What’s The Bad News?

Unfortunately, I cannot say the device is free. Although I got this device for free……this device is quite expensive. Without a student discount, the Analog Discovery costs $200, which is enough to get you a really good oscilloscope, function generator, or logic analyzer for that price.If for you are a college student, then you can get a 50% student discount, which will make the Analog Discovery cost $100.

In my opinion, if you have $200 laying around, I rather get standard EE equipment. However, if you move alot, and do not want to carry EE equipment with you where you go, then buy the Analog Discovery. You buy the Analog Discovery from Digilent’s website.


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Mojo Makes FPGA Board Design Open Source

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Last January, I’ve been learning how to use FPGAs, which I talked about in my Getting Started With FPGAs post.  To learn how to use FPGAs, I brought FPGA development boards, which can cost up to $110, from Digilent.com. Fast forward to March, and I found Mojo, an open source $75 FPGA development board, on Kickstarter.com. Based on what I’ve seen and tested thus far, I honestly think the Mojo board is a great introduction to digital design for electronic hobbyists and electrical engineering students.

What’s Under The Hood?
Unlike the Basys 2 that I commonly use, the Mojo uses a Spartan 6 XC6SLX9 FPGA. The Spartan 6 uses a 50MHZ clock, which is 10MHZ higher than the maximum clock frequency that a PIC18F can run.  In layman terms, it can run faster than most of my microcontroller/FPGA boards. The board can accept between 5V-12V, but can only output 3.3V for each digital I/O pin. Because of the Mojo’s 3.3V limitation, you’ll need extra hardware to use electronic items like servos, solenoids, etc. Finally, the Mojo uses an Atmega16U4 for the USB connection among other things.

What’s So Special About The Mojo?

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The Mojo board is geared towards making digital design easy for hobbyists and electrical engineering students by taking advantage of the board’s Atmega16U4 microcontroller, which is used to implement your digital designs on to the board. However, the Atmega16U4 is not just used for uploading your designs to the Mojo. The Atmega16U4 is used to communicate serial objects like serial LCDs, XBee wireless modules, and even Sparkfun’s FTDI breakout boards, with the Mojo.  You can even use the analog to digital converters included with the Atmega16U4 to allow the Mojo to take in analog signals.

What I Love About The Mojo ?

Although this seems like a petty thing, one of the key qualities I look for in a FPGA development board these days is the number of accessible I/O pins.  When I first heard that the Mojo will offer 84 accessible I/O lines, I immediately gave my pledge for the project  In fact, the lack of accessible pins for the Basys 2 FPGA board severely limited me in terms of FPGA projects. Embedded Micro even added 8 LEDs on the board for FPGA beginners to use. These LEDs are prefect for beginners as they implement simple modules using these LEDs. During the early stages of testing the board, not only did I create a blinking module for one LED, but I also used the same module to control the other seven LEDs on the board.

Despite the sheer number of I/O pins available, one cannot forget the fact that the Mojo is open hardware, which simply means that the Mojo’s schematic is available to view. This is crucial if you want to create your own FPGA development board, but do not know where to start. In fact, I will probably use the Mojo’s schematic in the future.

Work Done Thus Far ?

mojoservoCurrently, I do not have any project plans for the Mojo board. My focus has been learning how to effectively use the Mojo board. Recently, I learned how to control a servo using the Mojo board, even though most servos can only powered using 5V. I was able to control the servo by connecting one of the Mojo’s pins to the optoisolator’s input pin, and the servo’s signal pin to the optoisolator’s Vo pin. Although I could not find a power supply around, I used my Arduino board to provide the right power to the servo.

Where Can I Learn How To Use The Mojo Board?

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Although I am planning to write tutorials on how to use the Mojo board for this blog, you can visit Embeddedmicro.com, where you can read tutorials on how to implement serial communication, servo control, and other digital modules onto the Mojo. If you want to purchase your own Mojo board, then visit this URL. Please keep in mind that the Mojo board only cost $75.

Did anyone buy a Mojo board aside from me? Feel free to leave a comment about your impressions of the Mojo board!