Monday, February 17, 2014

Test Equipment: Clone Saleae Logic Analyzer


A fellow ham recently pointed out this very inexpensive Logic Analyzer  ($10 CDN) from seller mhestore2009 on eBay, and I had to get one. It is a much less expensive clone of the real Saleae Logic Analyzer. I thought that writing this short review might be interesting to others.

 
 
If this vendor does not have it any more, there are lots of others that do.
 
It came complete with a USB cable and some connector cables, you download the software from here.
 
It was dead easy to set up, and the software is very easy to use. Here is a screenshot of the display of an 8 bit binary counter (coming out of a PICAXE, actually), click on it for a larger version:
 
 
Next is a display of a serial communications stream from a Raspberry Pi and a dumb terminal (it seemed to pick up the 0 to 3.3 volt logic OK). Note that the software actually understands the ascii serial protocol and displays the characters transmitted along with the logic levels:
 
 

Lastly, here is the display of an I2C stream between a Raspberry Pi and a PICAXE chip:

 
 
As well as Serial and I2C, the software can decode and display SPI, CAN, 1-Wire, UNI/O, I2S/PCM, MP Mode 9-bit Serial (i.e. Multidrop and Multiprocessor mod), Manchester, DMX-512, Parallel, JTAG*, LIN*, Atmel SWI*, MDIO*, BiSS C*, PS/2 Keyboard/Mouse*, HDLC*, HDMI CEC*, and USB 1.1*.  (* currently in beta).
 
I have kind of mixed feelings about these Chinese clones using software that has been developed for more expensive hardware. It will be interesting to see how the real Saleae Logic Analyzer company reacts, maybe they will add a serial code or some other test to the software to block the clones from using it.
 
On the other hand, I think that makers and hobbyists are the main target for the clones, and maybe the company will allow the clones to use their software, assuming that real companies with critical projects will by the real thing from them. Will have to see how it plays out.
 
 
Eric Pierce VA3EP - See the Disclaimer in the Introduction

© Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", 1952-2099. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", with appropriate and specific direction to the original content.
 
 

 

 


Sunday, February 9, 2014

Test Equipment: Oscilloscope for less $30 CDN


When at the PICAXE site recently, I saw this really interesting and inexpensive assembled Oscilloscope board. Right after a Digital Multimeter, an Oscilloscope is the most desired piece of test gear for working on electronics. This one is very inexpensive and affordable and although limited to audio and slower digital frequencies, is still good for basic use, so I thought this review might be useful to others. Quoting directly:
     "Many people who enjoy electronics as a hobby or in education (where budgets are always tight) don't always need a super-high-end oscilloscope but instead rather require something that is very affordable yet highly usable in practice.
     The PCB-scope is just that - simple to use, yet with a full feature set as you will find on professional instruments. The Windows software is free of charge and the PCB-scope connects via a standard micro-USB cable (as used by most cameras, mobile phones and e-readers, not included).
     PCB-scope grew out of the earlier DPScope project to see how a PCB based scope design could be simplified yet still give the functionality, look and feel of a real oscilloscope."

All of the required documentation (including schematics) and free software (which does most of the heavy lifting) are available for download. I purchased one from a local supplier, ABRA in Montreal. This is what the bare board looks like:


The headers are not already soldered in when you get it, depending on your application, you can solder the single sided one on the top for connections, or the double sided one for plugging into a proto board.

If you read my previous articles on breadboards here and here, you know that I like to have things mechanically robust, so I decided to mount mine scope board inside a project box with external connectors to protect it from harm. So using basic hand tools, I cut holes in a small project box for the board in the bottom, access for the USB cable on the side, 3 BNC connectors (for analog channel 1 and 2 and trigger - most real 'scopes use BNC connectores) and a 4 port RCA female connector for the logic probe signals on the top.




Then I wired things up, using wire wrap wire and my manual wire wrap tool to connect from the top header (I did not solder the bottom header on) to the connectors on the front where the wires are soldered on. I used some heat shrink tubing to keep the connections to the BNC connectors from shorting out (the BNC connectors are from my junk box, and are PCB mount types).  The RCA connectors are also from my junk box, from a scraped DVD player.


Once the box was closed up (after testing) I added some labels using a ???? label maker.


Here is a screen shot of the PC software (most of the heavy lifting is done by your PC)  displaying a 1Khz sine wave from my ancient HP 204B sine wave signal generator on both channels. Yes, there is a bit of distortion on the top of the sine wave (which is coming from the generator, I confirmed that on my HP 1740A Analog 'Scope):


Believe it or not, this inexpensive Oscilloscope has the ability to display the frequency spectrum of the signal as well using Fast Fourier Transforms in the software. 


You will notice that there are large even harmonics at 2, 4, etc. KHz, and smaller odd harmonics as well. You will also notice that there are no calibrations for the scales on either screen (this is the way real 'scopes are). However, if you tick off the "cursors" box movable cursor lines will read off the values on the vertical scale, no matter if calibrated in volts or dB and on the horizontal scale. Also, on the Utilities menu there is a selection called "Measurement" which displays just about every parameter of what is shown on the screen.

The software also supports a Digital Voltmeter function as well as dual channel data logging to a file and 4 channel digital logic analyzer function.

One operational issue, I found that you should connect the device before starting the software, AND stop the software before disconnecting the device. I found that not doing it in that order resulted in it not finding the device on occasion.

All in all, pretty amazing for a $30 board.


Eric Pierce VA3EP - See the Disclaimer in the Introduction

© Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", 1952-2099. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", with appropriate and specific direction to the original content.

Saturday, February 1, 2014

Presentation: Raspberry Pi at the OLA Conference


I did a presentation on the Raspberry Pi at the Ontario Library Association Conference on Friday (as part of my "day job").




Here is the description from the presentation:

"ENGAGE ELECTRONIC MAKERS WITH A RASPBERRY PI WORKSHOP
Eric Pie
rce, IT Co-ordinator, County of Prince Edward PL & Archives

Since its release in 2012, millions of Raspberry Pi $35 credit-card-sized single-board computers have sold. Used by electronic makers of all ages to build projects such as media players, home automation and security, Internet-connected dog treat dispensers, and more. Learn how to present a hands-on workshop demonstrating the basics to engage a cross section of library patrons."


A lot of libraries (and schools) are doing MakerSpaces to engage patrons, and there were a number of presentations on this theme at the conference.




Eric Pierce VA3EP - See the Disclaimer in the Introduction

© Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", 1952-2099. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", with appropriate and specific direction to the original content.





Tuesday, January 28, 2014

Raspberry Pi: Python Traffic Light Program


Here is a very simple Python program to demonstrate the "Push your Pi ! 8 LED & 8 Button breakout board for your Raspberry Pi GPIO" from http://mypishop.com/ (I wrote about this board in an earlier post).

It used the left 3 leds for one signal light, and the right 3 leds for the other one. I know that the lights are all red rather than red/yellow/green, you have to use your imagination :-)



The program is very trivial, but hopefully easy to understand for a newbie. 

Make sure that you install the required RPIO package as described in another post.

Next step would be to use two of the push buttons to indicate traffic in the left turn lane and trigger a flashing advanced green.



Eric Pierce VA3EP - See the Disclaimer in the Introduction

© Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", 1952-2099. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", with appropriate and specific direction to the original content.


Monday, January 27, 2014

Test Equipment: Atlas DCA Semiconductor Analyser Review

 
Atlas DCA - Semiconductor Component Analyser - Model DCA55
 
 
 
I saw this advertised in the back of QST magazine a while back and it looked very interesting, so I just picked one up from a Canadian supplier. For the money (less than $100 CDN) it has pretty amazing capabilities. To quote directly from the manufactures website:
 
"The Peak Atlas DCA
A fresh approach to component analysis has resulted in the fantastic Peak Atlas DCA, an intelligent, slim and invaluable tool. A world of detailed component data has never been so accessible. Just connect your component any way round and press the test button. The Atlas DCA will then present you with detailed component information in concise, easy to read, scrollable pages. The displayed information will include: the component type, special component features, component pinout, and measured parameters (such as gain, leakage current, gate threshold voltages, volt drops etc...). No more searching through data books and catalogues in order to identify components and pinouts, the Atlas DCA does it all.

Analysis Portfolio
It doesn't matter how you connect the test clips to the component, the Atlas DCA can analyse a vast number of different component types including bipolar transistors, enhancement mode MOSFETs, depletion mode MOSFETs, Junction FETs (only gate pin identified), low power thyristors and triacs (less than 5mA trigger and hold), diodes, multiple diode networks, LEDs, bi-colour and tri-colour LEDs. It will even identify special component features such as diode protection and shunt resistors in transistors. For two-leaded components such as diodes and LEDs, any pair of test clips can be applied to the component any way round, the Atlas DCA sorts it all out for you.
 
Simplicity
There is no on/off switch, power is automatically turned on at the start of an analysis and then automatically turned off if inactive for more than 30 seconds. Each page of displayed information is presented in manageable amounts, with each page being displayed when you want it. If you want to concentrate on the "pinout" page then just select that page, you don't have to see information that you don't need."
 
 
In my tests, it does exactly as described above. I tried a few new semiconductors I had on hand, and it measured them perfectly. I especially like the fact that you don't have to worry about how to connect the leads.
 
I then grabbed a few components (from scrapped devices) from a box in my junk closet labelled "unsorted semiconductors". First one I took it determined to be an "Enhancement mode FET", and it rattled off all the parameters. Next one was a Silicon Transistor. Next I grabbed something that looked pretty old and probably was socketed, and it said it was a Germanium Transistor. Next it found a Darlington Transistor and even told me that it had a base to emitter resistor and a back connected diode from emitter to collector. I'm impressed. The wonders of cheap computer chips and clever software that make all this possible.
 
So if you are looking for a nice little semiconductor tester for building and repairs, this is just the ticket, IMHO.

Note that they have other test equipment, including a more advanced semiconductor tester that connects to your computer USB port, LCR and Impedance Meters, Capacitor Analysers, Network Cable Analyser, Thyristor and Triac Analyser and some other things.

 
Eric Pierce VA3EP - See the Disclaimer in the Introduction

© Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", 1952-2099. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", with appropriate and specific direction to the original content.


Sunday, January 26, 2014

Software: Good free remote computer access solution



If you are looking for a good free remote access product to get to your home computer or to help friends and relatives try TeamViewer (free for private use).

Works great for me (even works through the Xplornet double NAT).

Was using Logmein, but they cut off free support for that. I am glad I switched to TeamViewer as it is much better, imho. There is a windows app that you install, and it caches the long hex IDs and passwords on their website. So a single login to the app allows you to click and open any remote computer, slick.



Eric Pierce VA3EP - See the Disclaimer in the Introduction
© Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", 1952-2099. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", with appropriate and specific direction to the original content.

Saturday, January 25, 2014

Raspberry Pi: 8 LED & 8 Button breakout board


I picked up this interesting board from user 9030plc on eBay (visit store here). 



From the eBay description:

"Push your Pi ! 8 LED & 8 Button breakout board for your Raspberry Pi GPIO
Perfect way to learn how to use the GPIO pins.
Plugs into the Raspberry Pi GPIO connector.
Has eight bright green LED's and eight momentary switches.
For a more detailed discription see
For assembly and JAVA programing see
The normall connector sent mounts directly to the Raspberry Pi.
A box header is available at no charge but you must request it with your order.
Does not include Raspberry Pi or case. Requires assembly."

This would be a very good board for doing some beginner level programming without worrying about shorting things out on a breadboard.

I also found some other useful links concerning the board. Here are the vendors assembly instructions, but the ones above are more detailed. Here is a Python test program, but I find that the above program uses some advanced Python features that newbies may not understand.

Using ideas from it, I created this very simple Python test program that lights a led when the corresponding button is pushed, and should be very clear for the beginner.
Note to run the Python program above on out of the box Raspbian you need to install the module RPIO (which is an "advanced GPIO for the Raspberry Pi. Extends RPi.GPIO with PWM, GPIO interrups, TCP socket interrupts, command line tools and more"):

     $ sudo apt-get install python-setuptools
     $ sudo easy_install -U RPIO

IMHO this is not really a "beginners" soldering kit, you need a fine tip soldering iron (preferably temperature controlled), fine solder, good eyes and a steady hand. Some of the holes are very close and easy to create solder bridges across.

Eric Pierce VA3EP - See the Disclaimer in the Introduction

© Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", 1952-2099. Unauthorized use and/or duplication of this material without express and written permission from this blog’s author and/or owner is strictly prohibited. Excerpts and links may be used, provided that full and clear credit is given to Eric Pierce and "VA3EP Amateur Radio And Other Geek Pursuits", with appropriate and specific direction to the original content.