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Projects, videos and documentation from a Dutch electronics engineer

As I am redesigning the layout of the site some older projects might not yet be available here. But you can still visit the old website via https://meezenest.nl/mees_old/

Repairing a Philips PM32302024-04-06My dad found a Philips PM3230 oscilloscope in a thrift-shop. He has a blank check (but only if it costs 25 Euros or less), so he bought it for me. Fortunately the oscilloscope didn’t work…The reverse engineering of a Sonneteer Alabaster2024-04-05A Sonneteer Alabaster came in for repair. Unfortunately, it was in a bad state of repair. What started as a repair soon became a restoration. Because the modifications the amplifier had were typically done by a Dutch company this page is mainly targeted at Dutch owners. But if you are interested, you can try to let a robot translate it. The reversed engineered schematics are universal though...APRS igate with weather and telemetry2024-03-18This project combines the weather station with an APRS igate which has PE1RXF telemetry server capabilities into a stand alone APRS system.Weather station with ModBus interface2024-01-22A capable weather station with an RS-485 ModBus interface.RTTY like it's 19932023-11-01In a thrift store, I found an old Pakratt PK-232. I immediately got a great idea: participating in a contest with only vintage equipment.Repair Yaesu FT-757GXII2023-10-20This time a simple repair: replacing the dial lights of an old HF transceiver.Repairing a Sonneteer Alabaster audio amplifier2023-02-13As a former engineer for a high end audio brand I was pleasantly surprised when this repair came in.Repair Siemens EQ.6 Series 700 coffee maker2023-11-14For most of us, the day starts with coffee. But what if the coffee maker is broken?Amateur radio interface for digital modes2023-03-25As an amateur radio operator I like to make contacts all over the world. Besides voice (or phone), I frequently operate digital modes like JS8 or FT8. In my shack I use a bulky home made interface, which I named "Rig Interface". It works perfectly well, but as I plan to do POTA, or Parks On The Air, I need something more portable. I could buy a commercial device, but where's the fun in that? It is time for an updated design. It is time for "Rig Interface MK2".Home energy storage2022-09-08For more than 15 years, the roof of my house is covered with solar panels. But did you know that on average you only consume about 30% of the generated energy yourself? And with the ever rising energy prices that’s not good news. The best option is to store the solar energy in a battery for later use. That way, the energy generated during the day can be used in the evening. And if you know me just a little bit, you know I am always looking for nice projects. So, let’s begin!Atmega328p MQTT energy meter2023-01-11My old solar inverters do not have the option to read out the produced energy. But I do have a production meter installed in my distribution cabinet. But of course, this meter also does not have a data port. But it does have a pulsating LED...Repairing an SMA SunnyBoy 1600TL solar grid inverter2022-09-01By the magic of having two of them I make an attempt to repair at least one.Repairing a Quickmill coffee bean grinder2022-08-01My day starts with coffee. So, when my coffee bean grinder broke down, I had to repair it right away!Repair HP 8558B spectrum analyzer2022-03-13I had to repair this beast two times. And it is still going strong! Repairing a Philips PM3295 Oscilloscope2022-08-08The previous owner threw in the towel. I will take on the challenge! A new series…PE1RXF APRS server2022-02-01This build is an APRS server, designed for the 2 meter and 70 cm amateur radio bands. It is based around a Raspberry Pi Zero and has a build in FM radio as well as an option for connecting an external second FM radio. It also has a build in 433 MHz LoRa transceiver. At can be configured as a digipeater (single, dual, trifold or cross band), a TX and/or RX igate and - by means of some custom programs - can be used for sending and receiving APRS messages. It also can decode and process the custom telemetry data protocol from PE1RXF data logging devices. It is fully configurable by the command line and the most used functions are available via a web site.Raspberry Pi Pico LoRa APRS KISS TNC2023-01-13A mouth full, but a simple device. This is a KISS TNC, as used for packet radio and APRS, but equipped with a 70 cm LoRa radio. It can be used just as any other KISS TNCs with programs like aprx, yaac and xastir. Directly interfacing the software or via kissattach. It is also a successor of the Arduino APRS LoRa modem. It has 6 gpios and an I2C bus for interfacing sensors and sending telemetry over LoRa APRS. The KISS TNC is fully functioning, the Arduino APRS LoRa modem stack on the other hand is only available as a basic implementation in the code for you to play with. A basic example is provided: I designed a Power Distribution Box. You can send commands to the modem via LoRa APRS. The modem can switch four power supplies on and off. I also designed a version that switches 230V mains power sockets.The Tektronix 3A9 differential amplifier module.2022-01-13This module comes from a Tektronix 564B storage oscilloscope, but it is also useable in my recently repaired Tektronix 564 scope. A differential amplifier is very handy, indeed.The Tektronix 564 repair-a-thon2021-12-13One of my most used oscilloscopes is an old Tektronix 564 storage oscilloscope. When it gave up the ghost, I immediately reached for a screwdriver.Raspberry Pi LoRa shield2022-01-24A shield for the Raspberry Pi Zero 2 W with an SX1278 LoRa transceiver and a power supply with power on/off button to safely switch on and off the RPi. The software simulates a KISS TNC over TCP, so existing programs lile APRS, YAAC and Xastir can be used.Solar Generator2023-12-08This is the design of an off-grid electrical power system. It is intended for a tiny house I’ve build. The design philosophy is that a discharged battery should be charged within a days worth of sunshine, also in late autumn and early spring.The repairman2021-10-14This is a series in which I repair domestic appliances. Because I think that should become the norm again. If a device gives up the ghost, you should not automatically throw it away, but you should try to repair it. As I hope to reach a broad audience I shall not theorize to much and keep it practical. This way everyone with some technical knowledge can follow along. Building a modular transmitter.2021-10-20I obtained my ham radio licence more than twenty years ago and until recently, I had never build a radio transmitter. But all than will change. I will divide the transmitter design into seperate basic building blocks, and each block gets its own video. In no particular order: the PLL, the VCO, the modulator, the digital controller and much more.Repairing an L.E.D. tube light2021-08-19L.E.D. lamps should last forever, or at least several tens of thousands of hours. But what if that’s not the case?Etching printed circuit boards with the toner transfer method2021-07-25I make my own printed circuit board. It is fun to do and very fast indeed. You wake up in the morning with a great idea and before supper you are testing your working prototype.Repairing a broken cable using TDR2021-05-11A good power cord is worth its length in gold, or at least in copper. Because almost no-one is prepared to pay a decent price for a product anymore, the quality of the humble power extension cord is not what it used to be. Cheap plastics make for a stiff cable and using aluminium instead of copper makes it ever stiffer again. So when my old extention cord broke, I knew that there was only on thing I could do: I had to try to repair it by saving as much length as I possibly could.The Pinephone as my only phone2021-05-27I never owned a smart phone and I never missed having one, as I am not into social media. But I do like computers, so when the beta version of the Pine phone became available, I ordered one straight away. Maybe an Android device and an iOS device are both technically computers, without rooting them, you are not allowed to use them as such. And even when rooted, what can you do with them, without big tech knowing? The Pine phone is different: it is not a smart phone, it is a computer running Linux. Even better: it is your computer running Linux, as you have sudo rights out of the box! This blog describes my first steps trying to write an application for the PinePhine. Most tutorials assume you are already an experienced coder. But I’m a noob, so I had to figure out a lot of stuff that is obvious to the senior. So, if you are new to Linux application development for the graphical user interface, I hope you can learn from my struggles.A tour of my lab2021-05-11I outgrew my old camera, so I bought a new one. To familiarize myself with it, I shot a quick tour of my lab.A wireless doorbell and intercom2021-03-05I am in the garden a lot and there I can’t hear the doorbell. That’s why I, five years ago, I build a wireless doorbell with intercom. When it broke, I desided to give it a redesign.Repairing a Yamaha KX-390 cassette deck2020-11-13I found this cassette deck in a thrift store. A label on the top cover warned me, saying it was a hobby project. Which in thrift store speak means broken. For me that can only mean one thing: buy it to see if I can repair it.The repair of a Yamaha T-560 tuner from 19812021-01-09Another second hand shop find. The label on top suggested it to be a doer-upper. Which is music to my ears!The design of a switched mode power supply from scratch2020-10-25When I purchased a Commodore 64 home computer, the power brick was slowly dying. Because of that, it was not save to power on the computer. Repairing it was not an option, as the power brick is sealed in epoxy resin. An other solution had to be found. I like to do things the hard way, so I decided to design and build a new power supply out of discrete components. It had to be a switched mode power supply, of course. Because of safety reasons I did use a normal transformer to step down the mains voltage to 9 volts AC, but after that a buck converter regulates the voltage to 5 Volts DC. And because I like the good old 555 timer IC, I used two of these in the regulator circuitry. Just because I could!Loading PacMan on the Commodore 64, the hard way2020-11-01The new power supply for the Commodore 64 is ready. Now, I want to play PacMan. But that is easier said than done! The disk drive came without any floppies and the datassette does not work reliable. There is no other solution than to build my own interface…

Dutch only

Reparatie Bose 1800 eindversterker2020-08-07Deze Bose 1800 eindversterker stond al jaren in een oude schuur te verstoffen. Zonde natuurlijk, dus werd het tijd voor een opknapbeurt.APRS tracker voor portofoon2020-06-02Een portofoon met ingebouwde APRS-functionaliteit is erg duur. En iedereen kan een kant en klaar apparaat kopen, daar is geen kunst aan. De lol zit in het ontwerpen en bouwen. Deze APRS tracker, gebaseerd op een Arduino Pro Mini, is via USB volledig te configureren. Ook kan via deze USB poort de (open source) firmware worden gewijzigd. Locatie-informatie wordt periodiek of mbv SmartBeaconing uitgezonden. Je sluit de tracker aan op de microfoon-aansluiting van een portofoon en alles gaat vanzelf. Omdat de tracker geen APRS berichten kan ontvangen, is deze niet aangesloten op de luidsprekeruitgang van de portofoon en kun je de portofoon blijven gebruiken om een frequentie uit te luisteren. Wanneer je de portofoon wilt gebruiken om te zenden, trek je simpelweg de tracker uit de microfoonaansluiting. LET OP: de gebruikte USB-serial converter heeft een ontwerpfout. Een modificatie is vereist, anders zal de GPS-module kapot gaan. Een beschrijving van de modificatie is te vinden bij de bouwdocumenten. De geschatte bouwkosten zijn 25 Euro, veel lager dan een nieuwe portofoon. Je hebt weliswaar niet alle nieuwste snufjes, maar dat biedt weer mogelijkheden voor een ander projectje…1200 bps AFSK / Bell 202 modem2020-06-10Een universeel 1200bps radiomodem, dat afhankelijk van de gekozen firmware, gebruikt kan worden als APRS modem (ook TCP/IP over AX.25) of als draadloze transparante seriële verbinding (bijvoorbeeld als SLIP verbinding). Het is een variant op het MicroModem van markqvist (https://unsigned.io/) Dit modem maakt gebruik van een Arduino Uno V3, zodat deze direct aangesloten kan worden op een USB poort. De aansluiting op de transceiver is volledig galvanisch gescheiden. Het modem gebruik ik in een testopstelling met een HC-12 70 cm draadloze seriële poort en een Raspberry Pi Zero om te experimenteren met draadloze TCP/IP verbindingen. Ouderwetse 1200bd TCP/IP over AX.25 en een moderne snellere variant (SLIP) op de 70 cm band met de HC-12. Deze laatste is een kant en klare module die uitzend op de 70 cm band met een vermogen van maximaal 100mW en een snelheid tussen 5.000 bps en 236.000 bps.APRS telemetry, maar dan anders2020-05-13APRS telemetry via APRS messaging volgens PE1RXFRestauratie Philips 22RB382 buizenradio2020-05-14Deze buizenradio vond ik in een kringloopwinkel. Op het prijskaartje stond: “ter decoratie”. Ik nam de uitdaging aan…Restauratie Tektronix Type 564 Storage Oscilloscope2019-07-23Een oscilloscoop uit 1963 in originele staat krijgt een nieuw leven in mijn elektronicalab. Twee speciaal ontworpen printplaten herbergen de nieuwe electrolytische condensatoren. Reparatie van voedingsgedeelte en verticale ingangsmodule. Opnieuw afregelen van alle circuits.Extra aansluiting op ICOM IC-251E all mode 2 meter tranceiver2020-05-12Omdat ik graag wil gaan experimenteren met moderne digitale communicatieprotocollen zoals FT8 op de 2 meter amateurband, heb ik een oude Icom SSB tranceiver aangeschaft. Om deze tranceiver aan te kunnen sluiten op mijn computerinterface heb ik de tranceiver gemodificeerd, door achterop een aantal aansluitingen te realiseren.Curve tracer2019-07-15Met deze curve tracer is het mogelijk om snel componenten te testen op defecten. Omdat de curvetracer meet ten opzichte van massa kan deze ook gebruikt worden voor metingen in bestaande schakelingen.Revisie zelfbouw-voorversterker2019-08-01In de tweede helft van de jaren negentig van de vorige eeuw bouwde ik deze voorversterker. Nu is het tijd voor een uitgebreide revisie. Als extra ontwerp ik een nieuwe inschakelvertraging en standby-regeling.Signaalvolger2019-08-13Met deze signaalvolger is het mogelijk om snel defecten in audioapparatuur op te sporen. Een oude Goldstar radio doet dienst als versterker. Alles in stijl in mijn vintage lab. De aansluiting voor de Carlson superprobe geeft de optie om ook contactloos te kunnen meten.Regelbare scheidingstrafo met stroombegrenzer2019-07-27Om veilig aan elektrische apparatuur te kunnen meten, is het verstandig om een scheidingstransformator te gebruiken. Zo is het te testen apparaat galvanisch gescheiden van het net. Hierdoor wordt de kans op een elektrische schok verkleind.Externe referentie-ingang frequentieteller2019-10-28Om mijn oude frequentieteller/functiegenerator precieser te laten tellen, heb ik een schakeling ontworpen die het mogelijk maakt om naast de interne 10 MHz TCXO ook een externe 10 MHz referentie aan te sluiten.Restauratie Kyoritsu K-142 buisvoltmeter2019-11-25Een 6.5 digit multimeter is een mooi apparaat om te hebben, maar soms ben je meer geïnteresseerd in de trent van een signaal, dan de preciese waarde. Daarom kocht ik een oude buisvoltmeter, die ik vervolgens restaureerde en afregelde.Reparatie Philips PM3244 oscilloscoop2019-10-28Ik kocht deze kapotte 4 kanaals 50MHz Philips osciloscoop omdat het me leuk leek deze te repareren. Nadat de scoop gerepareerd is, regel ik het apparaat opnieuw af.

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