News items for tag electronics - Koos van den Hout

2020-11-08 RF knowledge helps fix completely different problems 2 weeks ago
For work I currently spent quite a bit of time in video conferences. I have an external webcam from work which gives a better image than the built-in webcam, but it regularly started giving problems in the image. Hickups or blinking images, suggesting some communications problem between the webcam and the computer.

Since the webcam, a Microsoft lifecam studio, is still being sold and advertised as works good with Windows 10 I thought it wasn't the age of the webcam or a problem with the drivers.

So I tried a different solution which is almost the standard solution of a radio amateur for interference problem: add more ferrite to the cables. The USB cable is thin which suggests to me there is not a lot of room for good shielding. Pulling the USB cable through a ferrite core twice right after the USB plug made the problems go away.

Tags: , , ,
2020-10-10 The igate is igating 1 month ago
pi4raz igate running showing packet
pi4raz igate running showing packet
I dug into 'how to build code for the ESP32' and found Installing ESP32 Add-on in Arduino IDE (Windows, MacOS X, Linux) and since I have the Arduino IDE working enough for the previous project with a programmable microcontroller: the nanoKeyer morse keyer I did the steps to add ESP32 support.

I had to find the right settings for the specific ESP32 chip and since it is labeled "ESP-WROOM-32" I ended up at ESP-WROOM-32: Uploading a program with Arduino IDE and used the settings 'Board: FireBeetle-ESP32', 'Flash Frequency: 80 MHz', 'Upload Speed: 921600'.

The sourcefile to compile and upload to the ESP32 in the pi4raz igate is pa2rdk/APRS_IGate/APRS_IGate.ino.

I changed the definition of struct StoreStruct for a bigger wifi password (64 chars) and noticed that after uploading the updated code the last parts of the StoreStruct got mangled. I changed to #define EEPROM_SIZE 174 which seems to fix this.

I will admit to doing a bit of cargo-culting here: just following some google results and fiddling a bit until it works, with limited idea what I'm actually doing and what the effect of my changes is. The kind of weird results I got after growing the wifi password buffer suggested clearly to me that I was looking at some sort of buffer overflow, so I started looking for buffer sizes.

But the igate is now talking to the APRS network. First results visible at PE4KH-10 tracked on

Tags: , ,
2020-10-06 Finished and tested the electronics of another project: the igate 1 month ago
After finishing the Raspberry Pi ntp server in the weekend I continued on a long-running project: the PI4RAZ igate I started working on in June (and ordered in September 2019). I dragged the soldering iron, the soldering mat and lots of parts downstairs to work on it on Sunday evening. Soldering lots of pins to an Arduino nano is hard work.

I finished the last soldering on Monday evening and had a long and hard look at all the connections and redid a few. I used a multimeter to make sure three really close soldering islands weren't connected, found two with 0 ohms between them in both polarities so I fixed that issue.

After that I took the plunge of actually powering up the print and it looks good. The display shows output and I can walk through the setup when I connect a usb cable to the ESP32 module.

I can't make it run yet: the space for the wifi password in the ESP32 module is only 25 characters which is not enough for our home network. So I will have to look into changing the code (it has an update anyway: Software update iGate - PI4RAZ) and find a working way to program an ESP32 from linux.

Tags: , ,
2020-09-02 An update to the home 1-wire network 2 months ago
For more than 12 years now(!) the house has temperature sensors using the 1-wire protocol. I recently redid some of the wiring between floors and I finally got around to rerouting the 1-wire network via this new route.

I also added a temperature sensor in the big room in the attic, we are thinking of using that room more often. To get an idea of how good that idea is we wanted to get an idea of the temperatures up there and that's what I have 1-wire sensors for! I soldered an 18b20 sensor to the end of a 4-wire flat phone cable, added it to the network and it's measuring.

So now 12 environmental temperatures are measured every 5 minutes: 9 in the house, one in the weather hut, one in the shed and one on the roof of the shed.

I also updated the 1-wire projects overview with how I use 4-wire flat phone cable in RJ45 connectors for 1-wire network. I had to look up how I did that previously before I could start adding new cables!

Tags: , , ,
2020-07-03 The GPS ticks! 4 months ago
I remembered the junkbox contains an active GPS antenna which I bought together with the gpskit gps unit in 2003(!). And some other bits and pieces included a SMA to BNC adapter so I put the little GPS antenna outside and connected it to the GPS/RTC Hat.

Before I was back behind a computer it was showing a location and within a few minutes it had a PPS pulse. I was used to cold start taking at least 15 minutes with the gpskit!

So I tested with ntpd talking to gpsd via shared memory. This gave an interesting offset between local gps time and a nearby ntp server.
$ ntpq -p
     remote           refid      st t when poll reach   delay   offset  jitter
*SHM(2)          .PPS.            0 l    6   64  377    0.000   -0.149   1.672
xSHM(0)          .GPS.            0 l    5   64  377    0.000  -104.51   1.943
+ntpritchie.idef    3 u  101   64  376    2.774    0.950  13.948
+metronoom.dmz.c    2 u   99   64  376   10.482   -0.844  10.638
$ ntpdc -c kern
pll offset:           -0.000136461 s
pll frequency:        -11.054 ppm
maximum error:        1.3748e-05 s
estimated error:      1.7071e-05 s
status:               2001  pll nano
pll time constant:    6
precision:            1e-09 s
frequency tolerance:  500 ppm
I'm not too happy about the fact that the GPS NMEA messages are seen as wrong, so I'm going to stop using gpsd and go for a setup optimized for timing.

Tags: , ,
2020-07-01 A new home timeserver: GPS/RTC board 4 months ago
The Raspberry Pi GPS/RTC Expansion Board from uputronics came in today (thanks mailman!).

Next part needed: a gps antenna. But that's on backorder with another supplier.

Also needed: time to install raspbian on the Pi and start testing.

Tags: , , ,
2020-06-29 Newish electronics project: an igate 5 months ago
Some time ago I saw announcements of an igate build project from PI4RAZ, the amateur radio club in Zoetermeer. An igate is a system that receives APRS messages and forwards them to the Internet aprs servers.

There is a distinct lack of APRS coverage here in Utrecht, so more places that receive those messages and pass them to the Internet are a good idea. A specialized repeater to repeat them on the air would be even better, but that needs a special radio license which is one step too far and expensive at the moment for me.

The electronics came in months ago, but time to pick up the soldering iron and start with the hard part wasn't available. I started this monday with that hard part: soldering a VHF module on top using something close to surface mounting. Just with a lot more space between the soldering islands than real surface mount. Still needed good light and a magnifying glass to check my work constantly. I only had to desolder one small blob of solder which went in the wrong direction.

After that I soldered the resistors. That went fine. After that my eyes were too tired, but the first step has been made.

Tags: , ,
2020-06-15 A new home timeserver on order 5 months ago
After earlier tries to have a nice GPS-based timeserver for my home network I noticed a simple but very effective GPS 'hat' for the Raspberry Pi, the Raspberry Pi GPS Hat from Uputronix. While the Pi's are already taking over the home network just one more could be a nice addition. In the longer run this will probably replace the shed computer.

So I ordered a Pi with an added dual-band WiFi adapter, a case, the GPS hat and a GPS antenna. The GPS hat has PPS support so I will get the time correct. With the instructions from 5 minute guide to making a GPS Locked Stratum 1 NTP Server with a Raspberry Pi it should be easy. If this all works I may even add the resulting Pi to the IPv6 NTP Pool.

Update 2020-06-16: SOS Solutions came back with some bad news: the uputronix Pi GPS Hat isn't available anymore. I'm now looking at the comparable adafruit hardware which is somewhat more expensive, but offers the same options.

Update 2020-06-18: And the adafruit hardware is also not available soon. I cancelled the GPS unit part of the order and I'm looking at sourcing a GPS module for the Pi from another source. The GPS hat which sossolutions no longer sells is originally from uputronics where a newer version of the Raspberry Pi GPS/RTC Expansion Board is listed as available on the site. Based on a ublox chipset which allows me access to a lot of the GPS data.

Tags: , , ,
2020-04-13 Beeping -- --- .-. ... . loud enough (2) 7 months ago
Today I had time to work on the transistor switching to make the morse oscillator work. As I noticed before the Kent Morse practise oscillator kit is powered directly via the key which draws more current than the nanokeyer I built can handle.

So I had to calculate a transistor switch. That's something I learned a long time ago when I did electronics trade school from 1985 to 1989. In Dutch: MTS electronica. That knowledge had to be dug up again when I did the advanced radio amateur course but since I didn't have to use that knowledge it all sunk away.

But, google to the rescue and I found lots of examples, but the easiest one was at Transistor as a Switch - ElectronicsTutorials which explained exactly what I wanted. The next item was 'which transistor'. The default NPN transistor is the BC547B, but the theoretical current through the oscillator is a bit more than this transistor can handle. But a fellow amateur had a few BC337 transistors spare in his junkbox, so I could continue with this project.

Today I did the drawing and the calculations. I looked up the specifications for the BC337 in full saturation, at which time the Vbe is 1.2 Volt, Vce is 0.7 volt and Ibase is 1 milliAmpere. So I ended up with a resistor of 6800 Ohm at the input (which is (9 Volt - 1.2 Volt)/1 millAmpere rounded) and after building it on a breadboard it went beep with an input current of somewhat over 1.0 milliAmpere.

Update: Second test was with the nanokeyer, which first gave no sound, but that was due to me turning the volume down on the practise oscillator. Turning it back up fixed the problem, and I now have loud morse!

In the end this is giving me a good feeling. I had a kind of problem I haven't had to solve in ages so I had to relearn how to solve this, I found the solution method and was able to apply it in theory, practice followed the theory and it all worked as designed.

Tags: , ,
2020-04-02 Beeping -- --- .-. ... . loud enough 7 months ago
Kent morse practise oscillator built
The Kent morse practise oscillator built
To practise my morse at the radioclub I looked for a simple morse practise oscillator and found Morse practise oscillator kit - Kent and ordered it at the beginning of Februari. It took a while for it to arrive, but it arrived and I built it in one evening.

It's a quite simple kit. Which means the power for the whole circuit runs via the morse key, in theory about 120 mA. And that is more than the octocoupler on the CW output of the nanokeyer I built is willing to deliver (50 mA). So I can't use the practise oscillator straight away, there will need to be a small amplifier in between.

Some searching suggests I can use a transistor as 'power amplifier'. Time to look at what I may have (which is not a lot) or find a transistor somewhere.

Solution: order a bunch of transistors in a collection so I have some in the junkbox.

Oh and: The dashes and dots in the title are the word 'MORSE' in morse.

Tags: , ,
2020-03-09 Newer power supply not yet delivering what I want 8 months ago
I did some more testing with the HP power supply I bought last November. In previous tests the output voltage seemed to be limited at 13 volts and it seems limited to 13.10 volt at the moment. The RM Italy HLA300V plus amplifier I have will only output about 55 watts maximum in digital modes so that's less than I expect. A higher input voltage may fix this, but I'm not sure how to get the power supply to deliver this and keep running. The previous power supply gave up in a busy weekend but before that the HF linear amplifier delivered more power. I have seen it go over a 100 watt on digital modes. The difference in output from the linear amplifier with 13.10 or 13.27 volt power is quite large, which surprises me.

Tags: , ,
2019-11-23 PC control of the TS-480 radio working again, including for remoterig 1 year ago
I dug into the "why isn't remote CAT control not working" on the Kenwood TS-480SAT with the remoterig setup and as the debugging session progressed I found out it wasn't even working locally. The Kenwood TS-480 radios have a male db9 connector just like the PC had, and the non-intuitive part is that it needs a straight-through cable with data lines and hardware flow control.

I had a bunch of serial cables and adapters cobbled together to get from DB9 female to DB9 female with wires 2 and 3 coming out uncrossed, but it did not have hardware flow control and that had worked one evening before but now it decided to go on strike.

Thanks to the visit to the "Dag van de radio amateur" (DvdRA) ham convention and the extra parts ordered on-line from Conrad I had enough parts to make my own serial cable with the right wiring, including covers for the connectors with the cable coming out on the side.

So my skills in building right serial cables using a soldering iron, flexible wire and an amount of patience were recalled. I am very sure I haven't done that yet this century. Old CAT-5E cables are a good source of flexible cable with 8 wires.

When I had a finished cable with hardware flow control I first did a local test before I started putting the covers on the connectors and when that did work fine I put the covers on, redid the test and switched to testing over the remoterig connection. That also worked.

Update: And for the laptop which doesn't have serial ports I activated the COM port to USB translation on the control side. It took a bit of searching before I found that /dev/ttyACM0 was the active port, so now I can run CQRLOG on the laptop with full control of the radio.

Tags: , ,
2019-11-16 Getting distracted by weird noises and listening to data from car tires 1 year ago
I was tuning across the 70cm amateur band and heard lots of weird noises around 433.92 MHz. Which is logical: that's the ISM band (industrial, scientific and medical) so lots of unlicensed low-power signals there.

That triggered me to update rtl_433 and see what I could receive. The answer after some searching how to build a running version: a lot. Including tire pressure monitoring sensors (TPMS) on a nearby car:

time      : 2019-11-16 15:33:25
model     : Toyota       type      : TPMS          id        : fb8c8bf9
status    : 128          pressure_PSI: 38.500      temperature_C: 6.000
mic       : CRC
There is indeed a Toyota parked across the street. I see three different values for 'id' suggesting that three wheels are 'awake' and reporting tire pressure data about every two minutes. According to eavesdropping the wheels, a close look at TPMS signals the sensors should only activate when the car is going faster than 40 km/h or when a special LF signal is active.
Read the rest of Getting distracted by weird noises and listening to data from car tires

Tags: , ,
2019-11-13 More investment in remote HF operation 1 year ago
So the order for the remoterig duo to work on my remote HF operation plans is out the door. I ordered them with HamShop to get Dutch warranty rules.

I also ordered some other stuff from Conrad to be able to get everything cabled correctly. I may have missed something but I hope to have enough to get going and be able to have frontpanel and main radio hardware separated by Internet.

Tags: , ,
2019-11-06 Tested and attached wires to the new 12V powersupply 1 year ago
Powersupply with wires attached
Powersupply with wires attached
I had time to do some soldering and I tested and wired the 12V server powersupply I bought last Saturday at the "Dag van de Radioamateur" ham convention.

The powersupply that I bought is an HP DPS-800GB A and it already had two wires to make it start up when input voltage is applied. I just soldered thick wires to the output terminals so I can connect it to the HF amplifier. Unlike the previous HP DPS-700 powersupply this one has two builtin fans so it won't overheat.

Time to test it with the HF amplifier is this weekend. I'll test the output power with the current output voltage left as-is. It's currently at 12.2 Volt when no load is applied. There are simple modifications to raise the voltage as described by Server supply DPS-800GB - PA0FRI.

Update: After some testing it's clear there are two problems: the output voltage of this power supply does not get very high before it switches off. About 13 volts. At that voltage the output power of the HF amplifier is limited. And when using the external amplifier I had a lot of problem with the connection between the computer and the radio. As soon as I started transmitting the computer started giving error messages about the communication with the radio.

So back to just the radio and its output power at the moment.

Tags: , ,
2019-11-02 I visited the "Dag van de radio amateur" (DvdRA) ham convention 1 year ago
Today was the Dag voor de Radioamateur edition 2019, and I went there.

My main todo item was to deliver outgoing qsl cards to the Dutch QSL bureau and pick up the new ones for Region 08. So I walked in with a big shopping bag and after visiting the Dutch QSL bureau market stall I returned to the car right away with a new box full of cards. After that I walked in again and started looking around. I was looking for certain parts I needed recently such as RCA connectors, 2.5 mm stereo jack connectors. I also had some specific things in mind such as a newer high amperage 12V supply because the previous server power supply smoked itself and an antennaswitch and serial connectors for remote HF operation which I found. I found no USBaudio and USBserial interfaces so those will be picked up in the next electronics web order.

I attended a lecture on the QO-100 amateur satellite and the story behind the Patch of the Year antenna co-developed by Remco PA3FYM.

I also met a lot of amateur radio friends, more than I expected!

Tags: , ,
2019-09-14 The nanoKeyer morse keyer in its case 1 year ago
The nanoKeyer morsekeyer in case with paddles
The nanoKeyer morsekeyer in case
I found help at the radio club, Kees PA5Z made his metalworking skills available and now the nanoKeyer has a nice case and works fine in it.

Earlier steps: the nanoKeyer tested and working after assembling the electronics, starting with the nanoKeyer kit.

Tags: , ,
2019-09-06 The nanoKeyer morse keyer is working 1 year ago
nanoKeyer morse keyer and morse paddle key
The nanoKeyer and the morse paddle key. Connections to the nanoKeyer from left to right: cw to radio, input from paddle and usb to the computer
After a few hours of thoroughly soldering and checking the results the nanoKeyer is done. I did find an error in my work so I had to get out the desoldering iron to fix it: I put the wrong resistor in one place.

Next step was to get the arduino that is the core of the nanoKeyer tested. There was an arduino nano included with the kit preprogrammed with the nanoKeyer software, but it still needed the print headers soldered: two rows of 15 pins and very secure soldering work. I did put the small tip on my soldering station for this work and used a magnifying glass to check my results. It seemed to work fine but I noticed soon the speed control potentiometer and the menu buttons gave no response. Both those functions use an analog input of the Arduino in the nanoKeyer. I had bought an arduino at a previous radio parts market so I tried that one. This one already had the print headers installed so there was less chance of causing a defect.

That one had to be programmed first, so I dove into getting the Arduino integrated development environment installed. After a few tries it seemed the only way to have working USB communications is to run the whole Arduino IDE as root (using sudo). Not very secure but at least I could continue my work. The right settings were made according to the nanoKeyer Firmware Upload Guide 2 and the Arduino nano I bought myself works fine. The result: sending morse code, changing settings with the menu button all worked fine.

The ultimate step was to get software controlled CW generation working. I soon found Winkey USB works in Linux - OK1RR which has a driver binary (no source unfortunately) which communicates fine with the nanoKeyer. The network UDP protocol is somewhat very binary so I used one of the cwdaemon test programs to get actual morse code sent from the computer.

Now for the (for me) hard part: making the right holes in the case. I'll try to find some help at my radio club.

Earlier steps: starting with the nanoKeyer kit.

Tags: , , ,
2019-09-04 New electronics project: a morse keyer 1 year ago
My learning morse is still ongoing and I'm taking the first steps in generating morse. I decided on a paddle as a first morse key to get the dot/dash (or better: Dit and Dah) timing correct automatically. Opinions on tbe best choice for first morse key differ: some say a straight key is the best, others say a paddle. I'm sticking with the paddle at the moment because I also have a tendency to develop RSI. Telegraph operators were the first profession to have cases of RSI so I hope to avoid that.

I recently bought a paddle: the uniHam UNI-730a which is a nice affordable paddle for a starting morse operator. With the built-in keyer in my Yaesu FT-857 radio it is possible to create good morse code. I use the option to create the morse tone on the radio without transmitting to practise sending morse. I check the results with the Android application Rx Morse.

But, I want to be able to participate in morse contests in the future. For those a cw keyer is necessary that can be controlled both from a paddle (or a straight key) and the computer. I was looking at options when a fellow club member mentioned he had a nanoKeyer morse keyer kit available that he wasn't going to build himself because his radio can do all that work. So I bought the kit from him, including case and I'm soldering the first parts.

Since all parts are through-hole, I am soldering with the components 'hanging' from the board. I want all components to be as close to the printed circuit board as possible so for some things that want to 'fall' I use rubber bands to make them stay close to the board for the first soldering connections. I do avoid warming up the rubber bands, they will probably break and/or burn causing a nasty smell.

Tags: , , ,
2019-07-20 Going full duplex with amateur satellites, part 14: Switch to FUNcube Dongle Pro+ 1 year ago
FUNcube Dongle Pro+ I saw a radio amateur offering a secondhand FUNcube Dongle Pro+ for a very reasonable price and remembered my work to get into linear satellites and the problems with the input filtering on an rtl-sdr while transmitting. So I checked the specifications for that dongle and saw a lot better filtering.

I decided to go for it and a few mails later the dongle was on the way to my letterbox. Literally, as it fitted in a small package that could be delivered in the letterbox. With tracking, so I received a notification from the package tracker app after the mailman put it in the letterbox.

There is good support for the FUNcube dongle Pro+ in gqrx so I tried that first. It does give some USB errors:
[46918.612090] usb 2-1: new full-speed USB device number 10 using xhci_hcd
[46918.762268] usb 2-1: New USB device found, idVendor=04d8, idProduct=fb31
[46918.762273] usb 2-1: New USB device strings: Mfr=1, Product=2, SerialNumber=0
[46918.762276] usb 2-1: Product: FUNcube Dongle V2.0  
[46918.762278] usb 2-1: Manufacturer: Hanlincrest Ltd.         
[46918.797477] usb 2-1: 1:1: cannot get freq at ep 0x81
[46918.803092] hid-generic 0003:04D8:FB31.0003: hiddev0,hidraw0: USB HID v1.11 Device [Hanlincrest Ltd.          FUNcube Dongle V2.0  ] on usb-0000:00:14.0-1/input2
[46918.917284] usb 2-1: 1:1: cannot get freq at ep 0x81
[46918.955162] usb 2-1: 1:1: cannot get freq at ep 0x81
It does show as a valid device in gqrx and I was soon decoding audio with it. The easiest decoding was in the VHF II FM broadcast band. After all the work with the 2 MHz wide spectrum from the rtl-sdr it takes a bit of adjusting to start working with 192 kHz spectrum from the FUNcube dongle but qgrx moves that bit nicely when needed.

To the computer, the dongle is an USB device with two subfunctions: an usbaudio device and a usbhid device. The audio device is used to deliver sampled radio spectrum and the hid device is used to control the dongle. This is why it's relatively easy to use softwarewise: modern operating systems have usbaudio support and usb hid control from a user application isn't too hard either.

One of the things I do want is a lot of interesting audio routing to be able to record both the downlink audio and my own audio. So I fired up pavucontrol and gqrx crashed. Restarting gqrx did not work until I closed pavucontrol. Some searching found gqrx crash with Funcube Pro+ which suggests to turn the device off for PulseAudio. Which may seem strange but PulseAudio is also using the alsa drivers which gqrx tries to use. I guess there is some conflict between gqrx and PulseAudio in dealing with the alsa drivers. After switching the FUNcube Dongle Pro+ in PulseAudio I could open the dongle in gqrx and play with audio settings for other channels in pavucontrol.

The setup with gpredict controlling the receive frequency of gqrx also worked fine, so this is looking good. Now to find out how things work on an FM or linear satellite.

Tags: , , ,
  Older news items for tag electronics ⇒
, reachable as PGP encrypted e-mail preferred.

PGP key 5BA9 368B E6F3 34E4 local copy PGP key 5BA9 368B E6F3 34E4 via keyservers pgp key statistics for 0x5BA9368BE6F334E4 Koos van den Hout
Other webprojects: Camp Wireless, wireless Internet access at campsites, The Virtual Bookcase, book reviews