Posts

So you need to replace the soldering iron on your Atten 8502D Soldering Station. You could just buy the heating element, but you can find a complete soldering iron with cable for less than $12 on eBay. So It’s easier just to replace the whole thing. It Doesn’t Work! I have ordered replacement irons before (I’m very rough with my soldering station) just to find out that they don’t work. You get the dreaded S-E or H-E message on display and, obviously, something is wrong. What do you do now? Read on to find out. ...

How to add an I2C interface to a Sonoff WiFi Smart Switch. The Sonoff brand is a whole series os IOT devices that use the esp8266 WiFi processor internally. The devices are easily hacked and are cheap. The Sonoff WiFi Smart Switch is the most straightforward device, which can turn on or off 110/220 Volt 10 Ampere remotely. That means you can have your ceiling fan, lamp or anything else connected t mains power remotely controlled by your phone or computer. But the software that comes with it isn’t very flexible and cannot be integrated into a home control system like NodeRED, OpenHAB or any other home automation system. Firmware The Sonoff devices are easy to hack, so you can put a better firmware like ESPEasy on it and integrate the device with any system. ESPEasy has an extensive list of extra modules that you can connect, like temperature, barometric pressure, humidity, light sensors, PIR sensors and a long list of other things. But most modules connect with I2C, which is a serial interface for interconnecting ICs using a clock and a data line. The Sonoff Switch only have one extra pin available, making it impossible to connect more advanced sensors. But there is a way of fixing that. Here’s how to add that to add an I2C connector to your $5 Sonoff and open up a whole field of stuff you can do. ...

What kind of impedance does this coax cable have? Sometimes you dig around in your parts bin, desperately searching for a bit of coax cable to make a new connector to your fantastic whizzbang widget. If you find a piece of cable without markings, how do you know if it’s 75Ω, 50Ω or some other impedance? Well, here are two easy ways of finding out. ...

With the resurgence of good Hi-Fi, where more and more people buy good headphones and listen to a lot of music thanks to streaming, it’s sad to see the things the mastering engineers (and in the end the artist) do to music. The recordings are getting worse. Even old records that get the “Remastered” or “Expanded” treatment doesn’t sound as good as the original. Why? ...

I needed a cheap heatsink for my Raspberry Pi 3 that I use as a music player/server. To maximize performance, I wanted to overclock the computer for faster searching and handling of all my music. I’ve managed to overclock my central Stratum-1 NTP server to 1350MHz without any problems, but the dinky little aluminium heatsink was way to anaemic, so I found a very cheap DIY solution to my question. With this heatsink, I can run the Raspberry Pi 3 at 1.5GHz all day at full tilt without any issues! ...

A friend of mine bought a new amplifier, but he wasn’t pleased with the sound. So he called me and asked if I could recommend a good old amplifier that could drive smaller speakers because he likes the aesthetic of older things. And the venerable NAD 3020B was the first one that came to mind. When I was young, this was the first affordable amplifier that sounded good. It’s not a powerhouse by any means, putting out (a very conservative estimate) 2 x 20 watts. But the phono stage accepts both MM and MC pickups which is excellent, and the sound quality is exceptional. So he scoured the used market and finally found a NAD 3020B. Unfortunately, when he got it home, there was a loud hum from the output. So I told him to send it to me so I could fix it. ...

I’ve been really annoyed with Eagle PCB because it has a bug on Mac OS X for a long time. When working with a PCB, pressing the middle button on the mouse for scrolling a layout, the program crashes. Thankfully I found a workaround. ...

[caption id=“attachment_4974” align=“alignright” width=“400”] Raspberry Pi 3 Overclocking Case Enclosure[/caption] The results are in: I’ve been very busy with different projects, and one of them requires a custom enclosure. So I thought it would be an excellent excuse to learn Fusion 360. When the Raspberry Pi 3 came out, I did some overclocking experiments. But I settled with just passive cooling with some small aluminum heatsinks. But after seeing some tests done with a more massive copper heatsink combined with a cooling fan, I decided that I wanted to build a case with a silent fan with enough room for a large heatsink. I need it for my NTP server at ntp.jacken.se to get better performance. ...

I haven’t had time to update the blog because I’ve been busy designing a new headphone amplifier. There’s been a lot of development when it comes to operational amplifiers and I was curious about how well I can get an amplifier to measure using the latest technology. The op amp I’m using still hasn’t got a development board, so I make one myself. The op amps are 5x5mm in PVQFN-20, so you need to use an SMD soldering gun or oven to be able to solder them. I simulated the circuit with both LTSpice and TINA90, but left biasing resistors and some other stuff in good old fashion though-hole components for easy testing. ...

After becoming a full-fledged time-nut (I’m compiling a new Linux kernel on my second NTP server as we speak), I have started to use the statistics that I usually install on a server just to keep a check on it. Sure, when installing something like MRTG, it’s great to see if something is clogging the system, but mostly, it’s unused. But when working with an NTP server a lot of factors start to make a difference. The temperature of the processor (the whole computer actually, mostly due to crystal drift), the load of the CPU’s, etc. ...