One small step for mankind…

…one giant leap for me! OK, that comparison is maybe a bit over the top, but I (finally) bought an oscilloscope for my lab so I am well excited!

I’ve never really had a scope myself and honestly never really felt I needed it that much (or had the space for it), but a few weeks ago I started writing some notes for the third installment of my “Tools of the trade”-series (you can find the two first parts here and here, but don’t hold your breath waiting for part three 😀 ).

Near the top of the list of “aspirational” tools was a signal generator (which I have) and an oscilloscope (which I didn’t have). I’ve also been looking at Neal’s page here to check out his versions of some of my designs and I noticed that he’s used a scope to do some measurements which looked interesting and sort of got me wondering what I could use a scope for if I had one.

I looked at digital scopes a year or so ago but got stuck since I couldn’t find an “obvious” choice within what I would consider a reasonable price range – I am just a hobbyist after all. My previous search had led me to the Owon 2102A which has some clear advantages in terms of hardware – mainly a 12-bit DAC and a higher resolution 8 inch screen. However, I’ve seen a couple of lukewarm reviews and several reports of buggy and poorly supported software and that was enough to make me forget about it (and it’s also “only” two channels). The Rigol 1054Z is also very popular and well-supported, but some reviewers say that the hardware in the Rigol is getting a bit long in the tooth so I discounted that option as well.

Having restarted my search I ended up with a Siglent SDS-1104X-E which is four channels and a bit newer than the Rigol. I did reconsider both the Owon (because I would really like the better hardware) and also the Rigol (which is cheaper), but in the end the Siglent seemed to be the best compromise. Several reviewers also made the comment that the difference between “scope A” and “scope B” is always smaller than the difference between either one and “no scope” and since I am a “casual user” I think it’s probably fine for me.

First impressions of the Siglent are quite positive, although it will take me a while to try all the different options and functions. It is also a bit noisier than I expected, but that’s not a major issue. If it’s too annoying in the long run I am pretty sure there are ways to silence the fan a bit without damaging anything.

Now, I honestly don’t expect massive changes with loads of advanced measurements in every post, but once I get the hang of using the scope (and the “image export” function) it’s quite possible that you’ll see some scope shots cropping up here and there… 🙂

Tools of the trade? (part 2)

A bit later than expected, but here is the second part of my “Tools” overview posts (the first part is here). This time the focus is on hand tools and other smaller “helpers”.

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Tools of the trade? (part 1)

I don’t honestly get a lot of tool questions, but in the interest of being prepared I thought I’d write up a bit of experience about what I think is necessary tooling (and which ones are just very helpful) 🙂 This got pretty long, so it’s going to be in (at least) two parts – the second one will follow shortly.

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Elektor softstart…

Over the summer, Elektor magazine has been giving away a free article every week to subscribers to their newsletter. Most of them have been interesting, if not especially audio relevant. However this week’s article is a new softstart based on an ATtiny microprocessor with IR functionality, ability to learn remote commands, audio signal detection etc. (so actually more of a control center than purely a softstart)

I haven’t looked through the details of the project and the software yet, but the article includes some softstart-math which is nice to have, and the combined project might well serve as inspiration for how to implement the features you want into your own project (because at least I honestly don’t see myself needing everything on offer here). You can find the project information here but be quick to grab it and save it to your computer because I expect it will be behind Elektor’s paywall again soon 🙂

Image (C) Elektor

ESP/Arduino accessories…

As I’ve spent more time working on my “IoT-T” design – I really should publish the files for that soon – I’ve found myself making a few additions to the main board. They are small extension boards that add functionality without cluttering up the mainboard – in no particular order:

– Different breakout boards to convert the I/O pins on the board to screw clamps for prototyping use or for easier connections.
– Board to add opto-isolation to a pair of digital out pins.
– A smaller watchdog timer to reset an IoT-device that is located remotely in case it freezes up for some reason.
– A breakout board for DS18B20 “One-Wire” temperature sensors.

Alone these boards are not really very impressive, but as extensions they really add to the versatility of the IoT-T main boards and they allow the mainboards to stay simple and universal. Of course these add-on boards can also be used for straightforward experimentation and prototyping, so I’ll be building a few extras to keep on my desk as well.

Experimenting with ESPs… (part 2)

One of the few projects that has moved a little lately is my ESP-based IoT-experiments (which started here). As mentioned then, I had just managed to crack how to do the mains-powered PCB layout I originally wanted to make so that’s what I have been spending time on building and refining since. Having a mains-powered board makes more sense when you need mains power for a relay anyway, otherwise a plug-in USB supply is just as good (or actually better/safer). The board is shown here in full prototyping mode, it is going into a case – of some sort – very soon.

Apart from adding mains power to the board I also removed the original DHT22 sensor and replaced it with an off-board BME280 instead. That was super smooth and it works even better than the DHT, not to mention that it also measures barometric pressure. I’ve been looking at other sensors as well (UV, air quality, light intensity etc.) but they don’t really make a lot of sense for my immediate application (which is remote monitoring of temperature and humidity in my basement).

Since I finished my original version I’ve made a few enhancements to the software and so now I’ve got the code for both LCD and web-UI mostly finished and especially the web part was a great learning experience. As mentioned in the previous post, it’s also a learning experience I am not sure I would have been able to complete without the help of the excellent ESP- and Arduino tutorials by Rui and Sara at, so obviously very grateful for those.

Now I can still do more improvements to the software but instead of picking at it for another six months I think I’ll try and package it up shortly and then publish it here so that someone else can hopefully have a go at it as well. Stay tuned! (but as usual, don’t hold your breath while you wait…)

Buying “suspicious” parts…

With the current trend in audiophile parts being that all the “old” audio grade parts that we know and love are either being discontinued outright or at least replaced with something in impossibly small surface mount packages, it’s almost inevitable that we all at some point face a choice between giving up on a project and sourcing parts from “questionable” channels such as eBay or Aliexpress.

Here are the questions I personally ask myself before buying something and while they are definitely not a guarantee against wasting your money, they might help someone decide when to take a (calculated) risk and when to pass up what otherwise looks like a good opportunity.

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Trial and errors….

Like most blogs, social media showcases etc. this page is to some extent a massive display of selection bias – you only see the stuff that works, and only when it works. You never (or at least rarely) see the things that don’t work. Because of that, I just thought it would be funny to at least give you a few examples of the memorable mistakes I’ve made during the life time of this blog – along with the lessons I’ve (hopefully) learned from them.

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Experimenting with ESPs… (part 1)

…ESP8266’s that is (if you hadn’t guessed that 🙂 ).

Although I am not directly involved with it, I have several colleagues at work that are looking at Industrial IoT applications for various use-cases. Quite a few of them have built personal home-automation systems of one sort or another, and as I would actually like to do a ittle bit of monitoring/control around my house as well I started looking at options a while back.

My old Ampduino project was of course a big inspiration, but the Arduino lacks onboard wifi which is a big drawback, even for “IoT” at home, and so the ESP8266 was a very logical step up. The original plan was to build from scratch using “raw” ESP-12 modules, but after a bit more research I stumbled upon the Wemos D1 mini. I then decided to go back to the original “Ampduino” approach of building a baseboard for a ready-made module instead. This gives a good amount of flexibility while at the same time ensuring that USB, programming and all other standard functions work as they should.

For once, I decided that I was going to get started on the software-part of this immediately (that’s usually my weak spot) and since I have had to wait three weeks for the fist PCBs to arrive I’ve made very good progress. Two things helped me along though: Firstly that I found a basic sketch at RNT that did a rudimentary version of exactly what I wanted, namely control via a web-UI. Secondly, I had a standard NodeMCU-board which I could pop in a protoboard immediately. That made it feasible to start getting individual pieces of the code together as soon as the PCB-order was submitted and then subsequently assembling the pieces of code into the “real” thing later on. My prototyping efforts while the v1.0 boards were in the mail also gave me input to v1.1 boards, so I can actually start placing those orders in a couple of weeks (no point doing it now because all the PCB factories are closed for Chinese New Year).

As usual for this type of project I’ve ended up making several versions of the board. The “original” version is USB- or DC-powered and has an onboard relay and an onboard DHT22 temperature/humidity sensor in addition to a couple of spare in/outs (analog/digital). The smaller version shown here ditches the onboard relay and instead breaks out a full set of SPI-pins. This allows connecting an SD-card adapter so that data from either the onboard DHT22 sensor or any of the other inputs is saved to a local card as well as being displayed on a web interface and a local LCD/OLED display (via I2C).

The original plan was to do a mains-powered version but I couldn’t get a good design together at the time and so I went DC-powered instead. However, I think I’ve cracked it now so the next run is going to include a mains-powered version as well. Other changes for v1.1 will be some routing improvements and (most likely) doing away with the onboard DHT22-sensor and replacing it with the option of one or more offboard sensors based on the BME280 and/or the DS18B20 sensors.

Board sizes are from app. 50-75mm squared, so these are quite compact and versatile. More updates and also some code samples later on 🙂


Once again I find myself in a period where “real life” is intruding significantly on my build time. Not only at work (which is the normal reason), but also in my personal life. Therefore, the progress I am managing on my projects is mostly so incremental that it doesn’t really make sense to write about it – it would be the DIY-equivalent of a book with every page as a separate chapter!

However, the inspiration for projects is still there and both the various online forums and my blog-feed serve as good sources of new ideas and inspiration. One recent example that I specifically think is worth mentioning is this post on Arduino “watchdog timers” for standalone Arduino projects where a self-reset capability in the event of an error is a good idea. Like all the other posts on the site, this is very comprehensively documented and easy to follow and in this case it’s a topic that I didn’t think about but immediately thought would be useful.

And the best part is that even if you are busy, sketching out a simple PCB doesn’t take that long – does it? 😀

(note: hat-tip to the referenced wikipedia-article for the image below)