Category Archives: Test Equipment

Electronics Test Equipment

How is my Saleae Logic 8 Logic Analyzer working out?

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I received my Saleae Logic 8 analyzer in the mail a few days ago. I pre-ordered it maybe a day or two after they opened up pre-orders for their new logic analyzers earlier this year. Last I checked they haven’t started shipping the Logic Pro 8/16 yet (USB 3.0/faster). I ordered the Logic 8 as I typically use the LA for 100KHz I2c and *kbaud serial analysis. Today I used it to check some singles on a microcontroller (16F1509). I flashed the micro with some sample code to confirm it worked; it did. The LA worked just fine but I noticed something and I’m not sure if it’s an over zealous algorithm, inductance, a ghost or what? I get a lot more wiggle in the analog display in the LA app than I do on my scope. Full disclosure: my scope has not been calibrated for over two years I still trust it’s input and I use it in the 10MHz+ range all the time, seems pretty solid. This is a 100ms transition off and on. I’ll be keeping my eye on this.. naturally I checked this at max sample rate (25MHz) after I noticed this.. same wiggle.

 

The digital and analog signal shown in Saleae Logic 1.1.24 beta using a Logic 8
The digital and analog signal shown in Saleae Logic 1.1.24 beta using a Logic 8

 

The same signal (channel 0) on a 60MHz Tektronix TDS1002B scope screenshot; I trust the scopes input.
The same signal (channel 0) on a 60MHz Tektronix TDS1002B scope screenshot; I trust the scopes input.

The same signal but with the analog view in 8x mode:

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I read through the online manual but I suspect the beta software documentation is lagging behind a bit. Version 1.1.21 said there was a “New voltage measurement tool for analog”.. I see there is a .25 just out so I’ll try that. Still, regardless I have zero regrets and love this thing. I like the bigger form.. I’m also glad they have these black ground clips but wish they would make two changes.

1. Channel 0 is a black leaded wire.. like all the grounds. Maybe white or any other color?

2. In the older application the channels were color coded in the application to match their wire leads.. that was nice 🙂

.. ask and though shall receive.. I downloaded 1.1.25 and there was my voltages. Didn’t even get to draft!

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This is a great tool and a must-have if you’re doing any kind of microcontroller work. Maybe I’ll try the Logic Pro’s out once they get caught up with all the pre-orders.

Electronics Test Equipment

A new bench-friend!

Who needs more kids when there’s spectrum analyzers to be had!

My new Toy! The Rigol DSA 815 Spectrum Analyzer
My new Toy! The Rigol DSA 815 Spectrum Analyzer

I haven’t had a lot of time to play with this because well, I just got it. I will sit down and really tear it up … I have filters-galore to design and tune now!

DSA815TG-1

Someone said they needed to take photos of the screen but there is a USB port and it does a find job of taking a snap shot to a drive.. maybe I have a new revision?

.. Next up.. Thursday night I picked up another VFD.. I have been looking for a smaller drive.. well unfortunately this one was really dead. After I pulled this board I looks like there was massive arcing to the ground plane. I also noticed the main inductor was cooked and the IGBT pack looked toasted.. this must have made a little noise went it went! At least I got a nice heat sink with fans out of the deal.

 

New-used VFD is nearly worthless...

Back to this last weekend: I am not going into what I’m working on because that’s a post for another day. I am working on something with my PIC Clicker… I accidentally toasted the boot loader  because I was throwing caution into the wind and felt like using my PICKit3 to program it… no need for any Mikroe C stuff… but in good faith of trying this out I reloaded the boot-loader from the hex file they provide online (thanks guys), downloaded Mikroe C, and have been writing code with it. I don’t like the change, meh. I can say if I was starting all over it would have been easier starting with one of the EasyPics or PIC Clicker and MikroeC. Lets see how it goes. Below is my first “hellow world” program blinking the LEDs..

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.. so if you feel like hooking your Clicker up to the PIC kit.. here is how I did it. The colors are in order there.. just pulled off the clicker.

PICKit3+PIC Clicker

I have hope of finishing up one project “mostly-enough” to post it mid week..

Analog Electronics PIC Test Equipment

An evening of measuring inductance

I was inspired by Alan Wolke’s ( @W2AEW ) video on measuring capacitors and inductors with an oscilloscope. I tried it out and it works pretty reasonably; yeah why wouldn’t it? Anyhow, if you can do it on an oscilloscope it can be done by a microcontroller right?  I have been trying to keep myself from buying this $220 eBay LCR meter on eBay.. it looks nice enough (model: MCH2811C). I needed to make this a project or I was going to pull the trigger on some Chinese garbage!

I went with simple and cheap, I don’t know how well it’ll work out yet but I bread-boarded a proof of concept design. It tested okay after some modification. The first road bump was I had found the PIC output pins had unacceptable rise time compared to 74HC14. The first change was using the PIC output to drive the 74HC14 HEX inverter to get the quick rise time needed.  I’m throwing a fast edge at the tank circuit that includes an “unknown” inductor and then I do my measurement, just as Alan used his homebrew TDR circuit. I went really low tech on my measurement circuit, I may change this. I used an LM339 comparator and a trimmer as a voltage divider. The first couple waves in the tank “ring” trigger the comparator and I measure the frequency by figuring out the time between the positive pulses by timer. Pretty simple no? It works fine as it turns out. I will have to get a better capacitor and ensure I measure it very accurately to do my math in the PIC and get a reasonable result.

Instead of the usual photos I made another YouTube video. It wasn’t a great one, one take, no editing.. it’s gets my point across (kind of).

My project proof of concept for the PIC L-meter. With the addition of a known inductor and a rotary switch and a little more code you can turn this into a PIC LC-meter in no time.

 

Electronics Test Equipment

The test equipment troll, are you buying the right equipment?

Everyone was the noob at some point; I get it, it’s easy to get hung up on the blinking lights and things with screens but shelf it! You don’t need the $4,000 Agilent or Tektronix scope… though don’t get me wrong it’s on my wishlist too.  I bite my lip on the message boards when I see a new-to-electronics DIYer who wants to buy a Programmable DC Load as one of their very first pieces of test equipment; to troll or not to troll?

What kind of “maker” are you? there seem to be a couple types of DIYers/makers out there. This is my attempt at stuffing you neatly into one or two of these general groups:

1. The arduino/raspberry pi maker.

2. The analog hacker

3. The experienced super nerd/internet “teachers” (FPGAs, 2.4+GHz RF experiments, SDRs, etc.. )

4. Robo-geeks

5. Solar/”Free”-Energy/electric car makers

I don’t really fit neatly into any one category in that list, and perhaps you don’t either? But if you’re truly a noob you’re doing to sit fairly solid into a of those groups; it’s really not group 3 though, right? Where do you fit? Maybe I missed one.. I’m not against revising this blog post to improve it.. got feedback? I’ll reconsider my list.

First off, everyone needs a solderless breadboard. You should have some kind of power supply for it. I recommend one of those cheap power supply boards made for breadboards and fits into both rails of a solderless breadboard that will generate 5VDC and 3.3VDC. Here is an example found at Tindie: Dual Breadboard Power Supply (all links open in a new window). I’ve always used the Jameco or 3M precut wire jumpers because they look nice and when you put them on a soldered protoboard for permanent use they look nice. However, recently I also started using those breadboard jumper kits you can find all over (example). I’ve been won over.. they are a huge time saver. Then purchase your hand tools, a wire stripper, small screw drivers, a small wire cutter.. and so on. Hand tools are something you can probably figure out yourself and you can usually almost everything locally.

Okay, so back to that list of electronics-type internet personalities…

1. So you’re new… who are you? Got that sweet new Raspberry Pi and you’re determined to make it do something cool? Blinking LED light, check! What do you need for test equipment now?

Somethings you’ll need:

Soldering Iron: You’re going to want to interface your Pi to the world, that means adapters, you’re going to have to solder. Don’t invest a ton of money right away, a little 25-35 watt iron will do just fine. Later on you’ll end up investing in some SMD equipment if you start making your own PCBs… wait until you know what you’re doing until you’re dropping cash on a Metcal system.

Multimeter: If you have a nice meter that’s handy but the reality is you’ll probably only be measuring voltage and resistance for the time being. Get something affordable and save your money for the next piece of equipment!

Logic Analyzer: Yep, I know tons of people will disagree but they probably don’t “fit” into the same category as you. I don’t have a logic analyzer, I use a scope and I hate it. I plan on buying a Saleae logic analyzer after Christmas (assuming I don’t get one as a gift). I hate programming my PICs without a LA. I have needed one on the last 4 or 5 projects I’ve worked on. A 8 channel unit will probably work fine, but if you have the cash a 16 channel is preferred. Make sure you can get one that can be set up for protocol detection/translation/monitoring(or whatever they want to call it) like.. make sure it does I2C. There are a lot of used stand-alone units from e-bay: Steer clear! if you have a huge income by a MSO, or a new LA. Those older units usually don’t have (all/some of) the cabling, are missing software, or are going to take up way too much precious bench room.

That’s it besides the common hand tools for small work. You will need other pieces of equipment as you pick projects you’re dedicated to finishing. Wait until then, save your money because you’ll likely find out you need something special and you’ll need it yesterday. Maybe a signal generator? Maybe you’ll cross into the analog work and you’ll need that oscilloscope. I do recommend buying a cheap used Tektronix analog scope if end up needing one. It’s most likely if you’re new you don’t need over 100MHz scope.. then save your cash for the MSO or you’ll just be another guy with 6 scopes sitting around you shop when you could’ve bough a ton of other equipment.

One last tid bit:I lot of new makers are Arduino users, and that’s cool if it got you into the hobby; they seem decent? I don’t own any, I have a love for the PIC microcontrollers, I think you should give them a try sometime.

2. Does anyone just decide to be an analog hardware hacker? Maybe you work on pinball machines, or retro TTL interfacing with old composite TV signals, audiophile, a ham just starting in RF? A lot of options here… this is where I started.

Okay you do need a scope, no way around it. I still recommend a eBay Tektronix scope, or if you have the money go MSO. I don’t trust the cheap Chinese stuff but if you feel comfortable with it, do what you have to do but you’ll probably get better performance out of a Tek 465 or 2246 than you will a $400 LCD toy from overseas. You can usually pick up an old 20Mhz “starter” scope for $20 at a ham swap, I would guess 98% of my use of a scope can be done with a 20MHz scope and for the first few years of my tinkering I never noticed a need for anything more.

You’ll need a signal generator. Used is fine if you trust your scope’s calibration or you don’t need precision… you’ll need a variable power supply, (dual +/-), the multimeter. I prefer using my Agilent bench meter but I also have three Fluke handheld meters. (87, 187, 73). Start out with what you can afford.

You’ll also need a solid soldering iron. I hate recommending these, but if I was I’m partial to the Weller brand. My next iron will be the WD1002. You can start with a 25-35W iron until you can afford more if needed.

I think analog hackers will end up spending the most money out of all the newbies… be careful. It’s easy to spend too much money on equipment you don’t really need and then need a ton more test equipment you have something you need specific to a project and no more cash to buy. Start with the original basics and then buy as needed. If you can save money and buy something that will work for more than just your current project. I keep a running tally of all the projects I’m working on and what I need (or what I think I need!) for them. I generally bulk orders for parts together and if I need test equipment I try to buy something I can use more than once.

3. yeah right, you’re asking the wrong person… fit yourself into a different category if you’re starting out. Take a look at W2AEW’s lab… or that South African YouTube vlogger (mlmorton I think?) .. that guy must have held up a test equipment store..  I can’t even guess how much is labs is worth.

4. Robo-geeks! You’re going to have it rough. You do a little bit of analog work, motor control, digital logic, programming.. I hope you have a lot of money unless you’re content with soldering kits.

You’re going to want to start with a decent soldering iron, you’re going to use it a lot if you’re serious.

A multimeter… that’s it. You need to save your money for all that machining, CNC equipment!

Okay, just kidding, kind of. You will need plenty of other equipment but it’s going to really depend what kind of robots you’re building and at what level. I’ve seen a lot of people crew up and work on certain parts of a robot. Start with the basics and work yourself into what you’re interested in. You’re likely going to fit into one of the first two groups or perhaps both unless you’re just the guy on the controls or strictly writing software.

5. I’m sorry to offend some of you solar or e-car guys sticking you with the perpetual motion machine guys (and gals!). If you’re “making free power” … go get yourself some PPE and a Tesla coil then I recommend a book on Physics and Electronics 101, and call it a day. The rest of you probably don’t really need much past a multimeter. You’ll want something durable don’t go with one of those cheap-o $20 home depot meters.. if anyone needs a bulky Fluke it’s you! The rough environments and mechanical tools boxes.. do yourself the favor. If you find yourself needing something else then go and ask around, but if you’re load testing batteries? Save some cash and go find a cheap load. Small baseboard heaters make cheap loads, you can also get some large surplus resistors at reasonable rates but don’t buy a programmable DC load to test your batteries..

One last thing: Solar Electric?! Unless you have to go off grid (a lot) or you’re rolling in an RV and want a battery charger stop wasting your money. Solar hot water is definitely the way to go as long as you have a decent amount of sun/M2C

Okay, there is a LOT of test equipment out there for you to buy and you will need a lot of it as you take on projects. I have a bench full of test equipment, a bunch on shelving in the garage and I still have a running list of things I want to buy in the semi-near future.. my list:

HV Power Supply
Programmable Power Supply
Programmable Load
MSO Scope
Spectrum Analyzer
RF Signal Generator
Oscilloscope 4 Channel
Arbitrary Function Generator

I have a lot of older equipment, plenty of it was bough for one project and entirely inadequate for others, I also have a lot of ham radio equipment like a HP universal bridge, Bird Watt meter, etc, etc etc.. most of my “affordable” test equipment came from ham swaps and eBay.. ham radio clubs can be a great source for pairing up with people interested in electronics (just avoid the guys with lightbars and more than 3 antennas on their vehicles… trust me.. avoid them).

Oh and on a final note: Dear Tektronix/Fluke, I would will like some of your equipment … a lot of it in fact, used it good! I’m not too picky 🙂 I promise to show it off often and I live like 5 miles away from you.. I’ll pick it up!