Archive for the ‘Technobabble’ Category

Notes: Setting up a modern Mail Server and Relay

Monday, September 19th, 2016

This is an attempt to clean up these notes:

References go there. This post is a summary.


Using LetsEncrypt with OpenLiteSpeed on Ubuntu

Wednesday, March 9th, 2016

These notes are based on this.

Install GIT and BC.

Get the latest version of LetsEncrypt using GIT, placing it in /opt/.

For the next step, we’re going to need access to Port 80, so temporarily shut down your webserver.

Run LetsEncrypt.

The first time this runs, it’s going to ask for an e-mail address.

If everything worked correctly, you’ll find your certificate files here:

Where is your domain name.

Next, inside your OpenLiteSpeed configuration, go in to your Listener->SSL settings. Add or modify them as follows:

Private Key: /etc/letsencrypt/live/
Certificate File: /etc/letsencrypt/live/
Chained Certificate: Yes

The rest of the fields should be blank.

That’s it. Start the server.

Updating your certificates

Your certificate is good for 90 days, but it’s recommended you update it every 60.

Updating is exactly the same as requesting, and requires you free up Port 80!

That will overwrite the certificate. The new certificate will be good for another 90 days.

I haven’t automated this myself yet, but there are suggestions how to do this in the article linked at the top.

Research: Value Oscilloscopes

Sunday, February 14th, 2016

So basically, this entire series of tool research posts is the result of me searching for an Oscilloscope, and then discovering my existing workflow was bad.

I’ve lost count at how many hours I’ve spent doing homework on low cost high value scopes. I’ve explored a variety of offerings from Siglent, Rigol, Owon, Uni-T, Hantek, and others, trying to find the best value. I don’t have the desk space for an old analog scope (which is a way to get a good scope for under $100). So I need a smaller digital scope to fit my setup.

I’ve tried to give each brand a fair shake, but in the end, all signs point to one.

Rigol DS1054Z

Cost: $399 US


– 4 Channels (Bonus!)
– 50 MHz (software upgradable to 100 MHz)
– Integrated Help
– Pretty much everything you want
– Small
– Low price (given what it can do)

– One set of knobs shared amongst each channel (versus separate knobs per channel)
– Fan could be quieter
– Not-so-great FFT (no substitute for a spectrum analyser)
– Many built-in features cost extra *

I’ve mentioned EEVblog several times, a very picky experienced EE, and this is his recommended scope.

After much fuss, too much reading, I can’t seem to find a scope in this price range that does everything as well as this one, and that even ignores the fact that it has 4 channels. You get 4 channels! Everything else in the price range has 2. Madness!


I’ve accepted there’s no other scope that even comes close. The only reason I haven’t purchased it, is that buying one will cost me about $650 CAD… which is a lot of money. Every non-oscilloscope device I’ve been researching costs under (or around) $100. $650 is a lot.

I’ve actually found cheaper scopes. has a few Siglent scopes for just over $400 CAD, no tax (roughly $300 USD). I got real close to buying one, but ultimately stopped myself once I realized it wasn’t the latest Siglent model (those cost about $800 base). Then I learned about some of scopes that, for whatever reason, can be hacked to become better scopes.

Actually, I do have an Oscilloscope. A really basic one I picked up in 2009 called the DSO Nano.


I’ve never really used it seriously, but it’s not exactly the most useful oscilloscope. You can buy a DIY kit for about $20 that does basically the same thing.

So yeah, scopes. I know what I want, but now comes convincing myself to spend the money.

Research: Fixing 858D Hot Air Stations and Fake Hakko Irons

Saturday, February 6th, 2016

Researching, I learned that China does make some good Soldering Stations, Hot Air Stations, even some good hybrids.


The problem is they assemble them wrong. VERY WRONG! DANGEROUSLY WRONG!

They don’t always do them wrong, but it’s best to assume it’s wrong.

If you’re up for a challenge, have another iron at your disposal, and are willing to do the homework, you can fix your cheap Chinese Iron. Replacement parts are extremely cheap, so even when things do break down, it wont cost you much to keep it going (or replace it outright).

It’s a project though. IMO, a good one for a hobbyist.

Dave from EEVblog speaks highly of his, but his does appear to be assembled correctly.

This is a video with more than 200,000 views, so it may have sparked increase interest in these cheap Chinese devices. Analysis of more devices shows most of them are incorrectly assembled though.

Above is a thread talking about this. In it, many people discuss the problems they found, with some talk of fixes.

There isn’t a guide for how to fix these. You’ll have to read the thread, research what they’re talking about, and try it.

I’m hoping to find some additional references from folks that fixed theirs.

So far, here’s what I’ve found:

I’m planning to buy one myself. I actually ordered and cancelled a few units from Amazon today, as I learned more about this. Initially I assumed one of the bulkier devices would be more reliable, but I don’t have a lot of space in my “laboratory”. So I’ve decided to research the Chinese models, and find a good 2-in-1 unit, and fix it.

One of the problems ordering the devices from China however is that most of them appear to be 220V. 110V (and 120V) seem to be included in *some* product descriptions, but some of these listings don’t really instil much confidence. I’m using 5 star orders from US/Canadian customers to gauge successes here, but sometimes I can’t find them.

So, this is an ongoing research project of mine. I will probably order one from China instead of Amazon. That way, I have more choice of layout. I’ll make another post once I’ve decided on my unit.

EDIT: Transformers

This is a very good video that explains how a standard transformer works.

I like that it actually explains the difference between some 110V and 220V transformers… just a simple rewiring.

UPDATE: Decided against 2-in-1

Well my hope was to find a good single device with both features in one. But ultimately I decided to buy separate units.

The reason is because no matter where I looked, nobody seemed to have anything positive to say about the irons in the 2-in-1’s. In fact, I’d come across videos like this where the iron breaks during the video review.


So instead, I’ve decided to try a fake/counterfeit Hakko 936. Hakko being a top quality Japanese maker of Irons.


The 936 is actually an obsolete iron that’s no longer made.

Now, this is not the same thing as the clone Hakko’s.


The clones all have strange company names, the same case and product code, but there are actually a some subtle differences. For one, the connector used by the irons is actually the opposite (female instead of male), so it’s not directly compatible (even though it’s effectively the same).

Now I don’t know if this is actually true, but I get the impression that the fake/counterfeit ones are better made than the clones. At the very least, they appear to try harder to make you think they’re real authentic units, from the quality of the packaging, to the English manuals and data sheets they include. I’ve yet to find a good teardown/unboxing of the fakes in English, but these Russian ones do fine.

Of course, when I say “better made”, it’s a loose suggestion. I still wouldn’t trust plugging in the devices without tearing them open first. But it’s all about the little things they appear to do in the fakes unlike the clones to convince you they’re authentic.

Not to mention, you can cheaply buy replacement parts for everything, from the irons, the heating elements, even the sockets and main board.


You could literally build one from parts.

So this is why I decided to go with a fake Hakko, for the repair-ability. My unit comes with a spare heating element, but I also ordered a spare iron, spare board, and spare connector. $10 in parts that should let me correct any issue that crop up with this $40 iron (I still have my junky old Weller iron as a backup to do said repairs). Really, the only thing I’m missing is a spare transformer and case. 😉

As for the standalone SMD Station (hot air gun), I actually bought one off Amazon. It’s totally one of the same cheap ones you get off AliExpress, but frankly price wasn’t any better if I was to order direct.


Despite the photo, I’m not entirely sure the unit has those memory recall buttons. The Amazon page has variants with and without, and people that own them have suggested theirs did not have the buttons. TBD.

Also the other problem, Chinese new year. It’s ongoing these next few weeks, and it’s going to add a HUGE delay to the already slow shipping (normally a month+). The SMD Station is warehoused at Amazon, and should be here Tuesday. IMO I actually need the SMD Station more. I currently have no way to shrink heat-shrink-tubing (aside from a book of matches). So I’m looking forward to that so I can start doing scientific things with heat.

Since this a standard Chinese unit, I grabbed a replacement heater from China as well.

Unfortunately I don’t have a way to correctly measure/calibrate temperature, so I’m just going to have to guess for now. I did order a cheap temperature gun sometime ago (hopefully showing up soon), but an actual heat probe would be much better here. None of my meters have temperature probes.

Anyway, that’s that. Now we wait.

Research: Value Bench Power Supply?

Tuesday, February 2nd, 2016

I dabble with micro-sized computers. Things like this.


The device above is something called the Orange Pi One, a cheap Chinese designed and manufactured board. Costs about $10 + shipping (~$4 to Canada).

Unlike the highly regarded Raspberry Pi Zero, it has a Quad Core ARMv7 CPU (vs. a single core ARMv6, slooow), a full sized HDMI, full sized USB, and an Ethernet Jack. Pretty amazing little machine for a tenner.

The Orange Pi boards have 2 things that make them slightly troublesome.

  1. Software support isn’t great. The AllWinner H3 lacks mainline support in the Linux Kernel, but it is getting better. Maybe by the end of the year.
  2. It doesn’t use the “standard” Micro USB port as a power connector.

The power supply part is unfortunate, but there is a workaround: The device CAN be powered via the expansion header.

Most of these tiny boards require 5v 2A to get the most out of them. Many modern cellphone chargers do meet this spec. I could just sacrifice one of those, chopping off the end and soldering pin headers in their place (I probably should, as this is common enough). I went down a different path though.

Bench Power Supplies

Any true electrical engineer has a true bench power supply. Unfortunately, a good one tends to cost hundreds of dollars.

The high-quality budget alternative tends to be converting an old PC power supply in to a bench power supply.


This makes a lot of sense, since PCs are already quite sensitive to voltages, so extra care is already taken by good PC Power Supply manufacturers to make reliable units. That, and the pins on the ATX connector are already the common voltages that most things need.

Sick of Beige basic case

Alternatively, you make or buy a simple daughter-board that takes an ATX connector, and gives you the desired outputs.

That said, the right of passage of any hobby electrical engineer seems to be making your own bench-top power supply out of an old PC power supply. Some day I’d like to do this, but not today.

“Buy an old used one instead”


I’ll admit that’s kinda cool, but at the same time unwieldy and large. I don’t have a dedicated workbench. I do this so infrequently, that I have my office desk I work on. I keep some ancient hardware around (Commodore 64, retro game consoles), but for the most part I prefer newer technology.

I like portable. I do most of my work on a laptop.

Despite the reputation of cheap sub $100 power supplies, I wanted to be 100% sure that they were “all crap”, as everyone says.

I hate being told absolutes without evidence, so I checked the evidence.


Cost: ~$60


This was the first PSU I found that really got me excited. I love how tiny and small it is. And the price… well, at the time I accepted that $60 would be an acceptable price to pay.

Alas, looks can be deceiving, and a deep dive reveals what’s inside is a bit of a nightmare.

Such a shame. It’s petite, and not bad looking. Functional (?) but scary.

KSP 305D

Cost: ~$60


Here’s another small one like the MCH above. It has a 2nd set of knobs for fine control (I’ve heard this is a recommended feature), but only 2 lines to tap (no earth ground).

The problem with this one though…

…it doesn’t exist.

Now, don’t get me wrong. It sort-of exists, but I can’t for the life of me find a photograph of the internals. I can find plenty of external shots. I can find dozens of alternative product codes (KSP303D, KSP605D, etc), models with different connectors, but apparently nobody owns one.

The Flat One: CPS-3205

Cost: ~$60


Instead of being tall, here’s a flat one. Of the power supplies mentioned so far, this may actually be the best so far, but it’s not without it’s problems.

It’s the first one that is able to safely power on without spiking, but Dude in the video above does actually manage to make it spike, under certain conditions. The video is a bit slow getting to this, but this does worry me that spikes may be inevitable in this cheap gear. I want to come back to this video sometime so I can hopefully better understand what he did to spike it.

It’s worth mentioning that the spikes appear to only be double the current, so a compromise appears to be setting the initial levels lower, then raising it.

Unfortunately, due to the clumsy user interface, this device requires a bunch of clicking and mode switching to change the levels.

If only there was a device that could be cleanly powered on with per level control?

The Anomaly: UNI-T UTP305

Cost: ~$90


Hey! UNI-T is back with a slick little unit using their lovely black and red theme.

The asking price is about $30 more than the above units, and amazingly, it may actually be worth it.

In the video above dude was unable to make it spike at all. This seems impossible for a sub $100 device, but lo and behold.

Now, to be fair, he hasn’t done the same extensive number of tests the dude in the CPS-3205 video did. It may still be possible to spike the unit in those same conditions.

The same video author loved his unit so much, he bought a 2nd one.

He also modified it to slow down the internal fan (and thus reduce the noise). I’d be tempted to make the same mod myself, but perhaps on a switch.

Sounds great right?

It does, except for one minor detail.

For some reason, UNI-T doesn’t acknowledge the existence of this device on their website.

I’m sure it’s just an oversight though, but even after digging, they don’t even sell them in their Chinese online store.

However, it is worth noting they do sell a 220v white model, exact same box, different product code for about the same cost. Some stores are listing it as discontinued, so this new red box with the switchable AC voltage is probably the new model. Not to mention, it looks way cooler in Red+Black.


UNI-T comes through again. In my research of other UNI-T devices, I found that they appear to do everything safely, but cut back in areas of little consequence (connectors that could wear out/need repairing, simulating automatic hold by using a 6 second timer). Their compromises don’t seem dangerous like the bargain models above, but I would strongly avoid pushing the limits of their devices.

I’m very tempted to grab the UNI-T device. While a modified PC power supply will do the job, I’d really like to have something that can limit the current. Maybe it’s a minor point, but that to me seems like something to have. Paired with a modified PC power supply for the big current draws, you could probably do most power work.

Tempting. Very tempting.

Research: Value Multimeters for Micro Electronics

Sunday, January 31st, 2016

I did a bunch of homework on Multimeters. Here’s a good beginners guide.

And here’s a more technical guide to buying a good meter.

There’s a ton of great information packed in that video, but unfortunately dude is an experienced no-compromise electrical engineer, so his minimum recommendations cost around $100. And actually, his advice is correct if you have any interest in doing any real electronics work (Cars, AC devices, or really anything more than microcontrollers).

But for me, I’m only really interested in micro electronics. Computers and small devices that draw around 5v or 3.3v (*maybe* as much as 12v), and only a few Amperes. I.e. things like the Raspbery Pi, Arduino’s, old PCs, old video game consoles, etc.

Pro gear is ideal, but I’m not a pro. I do electronics to learn, not to do anything important. Still, I highly recommend that video because it’s packed with experience.

In my research, I chose a Chinese manufacturer that EEVblog doesn’t like, mainly because they compromise (but when I get to talking about Power Supplies, you’ll see other manufacturers compromise WAY more). Again, this dude is a real engineer, and he needs a reliable device that can deal with high voltages (outside the scope of my hobby).

The devices I’ve chosen I believe are ideal for me, and are capable of some higher end work, with the understanding that extra care must be taken when dealing outside the 3.3-5v range, plugging in to the wall directly, etc.

Junk Device: Generic A830L

Cost: $3-$6


To be honest, the product code isn’t even that useful, but there a bunch to be found.

This meter is junk. It’s one of 2 meters that hover around the $3 price range. I’ve included it just to list the cons.


  • It beeps
  • Resistance tester
  • Diode tester
  • Transistor tester (hFE) *
  • Backlight *
  • Kickstand

Only two (*) redeeming features, but that doesn’t mean they’re good.


  • Manual range!
  • Poor precision options
  • Combined Voltage and Ampere plug (Unsafe)
  • Manual hold button (not automatic, need a free hand to use it)
  • No Capacitor tester
  • No Oscillator tester
  • No Duty Cycle tester
  • No Temperature tester
  • Low quality connectors
  • Unfused 10A line
  • May have bad leads (order some better leads)
  • 4 digits of precision (????)
  • Kickstand might break
  • Don’t plug in to AC Mains

Frankly, you might spend more money on the 9V battery.

We can do better!!

Value Low End Device: UNI-T UT-136B

Cost: ~$16


After doing my research, to me this appears to be the minimum quality meter you should own. I currently own 2 junk meters I bought from Radio Shack, and I’m pretty sure I spent $60+ on the one because it was “automatic”. What a difference a decade makes.


  • Separate Voltage and Ampere lines (Safety!)
  • Micro Ampere and Milliampere measurements
  • Automatic decimal place (manual isn’t cool)
  • Good+Fast beeper (lagged sound is really stupid)
  • Resistance tester
  • Diode tester
  • Capacitor tester
  • Oscillator Hz tester
  • Square Wave Duty Cycle tester
  • Some sort of Sine Wave feature (I forget why this is useful, maybe AC power *shrug*)
  • Fused 10A line
  • Kickstand…
  • Support for sleeved banana connectors on leads


  • Manual hold button (not automatic, need a free hand to use)
  • Some Capacitor testers have a socket for caps, but not this one
  • Not the best quality banana connectors
  • May have bad leads (order some better leads)
  • Fuses are not best quality
  • 4 digits of precision (4000)
  • No transistor tester (not that important, but some devices do this)
  • Kickstand might break
  • No backlight
  • No Temperature tester (UT136C model replaces a feature with temperature)

Here’s a comparison versus a better meter, and while it’s not perfect, it does keep up where it counts.

And more specific breakdown.

I’ve ordered one of these. I think it’s adequate for my needs, but of course I want one of these:

Value High End Device: UNI-T UT-61E

Cost: ~$47


It includes a few accessories.



  • Separate Voltage and Ampere lines (Safety!)
  • Micro Ampere and Milliampere measurements
  • Automatic display with voltage range graph (I forget the name)
  • 5 digits of precision (22000)
  • 6 second automatic hold (not truly automatic, but 6 seconds works)
  • Supports removing the delta of the lead resistance (RMS?)
  • Track and toggle the Peak (Min/Max) Levels
  • Good+Fast beeper (lagged sound is really stupid)
  • Resistance tester
  • Diode tester
  • Capacitor tester with socket accessory
  • Oscillator Hz tester
  • Square Wave Duty Cycle tester
  • PC Connectivity via SERIAL
  • Fused 10A line
  • Kickstand…
  • Support for sleeved banana connectors on leads


  • It occasionally spikes (rarely)
  • May have bad leads (order some better leads)
  • Fuses are better than the other model, but may not be the best
  • Not the best quality banana connectors
  • No transistor tester (not that important, but some devices do this)
  • Kickstand might break
  • No backlight
  • No Temperature tester (UT-61B and UT-61C models replaces features with temperature)

You can find a very in-depth 4 part video series here that tests and even calibrates the device:

And a comparison of other meters in the same quality range (albeit higher cost).

It’s not his favourite, but admits that it’s ideal for what I describe as my usage scenario (plus it has very high resolution).

EEVblog hates it because of the quality compromises.

Anything better?

A better device would have the following:

  • Backlight
  • Fast Display Refresh Rate
  • Good/Sharp Leads
  • Better Fuses
  • Better Banana Connectors
  • Rubberized Casing (to help when you drop on a hard surface)
  • Better accuracy and precision
  • Clean levels (no false spikes, likely a software bug)
  • Temperature tester
  • Safer lifetime on AC mains

I’m nowhere near experienced enough to take advantage of a better meter though. Better stuff costs more (Over $100), and as a hobbiest, I don’t need it. Because I don’t have pro gear, there will be times I shouldn’t trust my meter (i.e. occasional spikes, get a 2nd opinion), but it will be more than enough for what I do.

From what I’ve seen, in the price range (~$50), there is nothing better.


At the time of this post I’ve ordered both the junk tester (A830L) and the UNI-T UT-136B. Why the junk? As a backup mainly (or worst case, parts). The meters I have today are really bad.


The Radio Shack meter, while automatic, is lacking a lot of useful features like a beeper. Even the junk meter has a beeper!

Some weeks ago I ordered one of those temperature guns (a cheap one), so I’m hoping that’s enough for temperature measurement.

Things from China take weeks, even months to arrive. It’s Chinese New Year, so there’s at least 2 extra weeks to wait, so I probably wont see any of this until mid to late March.

At this time I have *NOT* purchased the UNI-T UT-61E, but you might say it’s on my xmas list. 🙂