Adventures of a Tech, avonturen van een techneut

 I just received my second batch of PCB's from JLCPCB with components assembled in China. How good is it really, we will find out soon enough. Everything works fine. Need to wait on correct USB-C connector, UART works, no problems so far.

In mijn vrije tijd werk ik aan leuke hobbyprojecten als deze. (die ik ook open source maak) Een 7 GHz prescaler voor RF-toepassingen en frequentiemetingen/tellers. (versie 2) Aangezien de frequentietellers met lagere prijzen een beperkte bandbreedte/snelheid hebben, moeten we deze prescaler toevoegen om de klus te klaren. Het bevat een OLED-display, een AVR-microprocessor en een HMC983LP5E van ADI om het HF-gedeelte te doen. Met behulp van de MCU (328PB) kunnen we een willekeurige verdeler ratio selecteren. (over SPI-interface) Met behulp van een D flip-flop van post scaler kunnen we er zeker van zijn dat de duty cycle 50% is. (Dit was een probleem in versie 1) Ik ontwerp/maak dit omdat mijn radio-amateur-vriendjes het nodig hebben. Ik werk/speel niet op deze hoge banden, maar dit is leuk. Het ontwerp van het schema en de layout is gedaan met KiCAD, simulatie met LT-spice. Software met behulp van GCC (gewone c-code) Behuizingsontwerp wordt met Fusion360 gedaan, gefreesd uit aluminium o...

Everywhere I look on the Ali and Ebays I see these step down converters based on MP1584. I bought a couple and actually they are not bad at all. The output voltage is set by the trimming-resistor in the left top corner of the picture. This works OK, but.. it is dangerous because it is rather sensitive to the touch. I decided that I wanted fixed output, so I had to figure out how this thing worked. The datasheet looks like this : R1 in the datasheet is what I call "R feedback" in my image. The value of R2 is mostly 8.2K Ohm in the boards I have seen.  So to set some common values for output voltage: change R1 to 27K for 3V3 output (actually 3.4 volt, but 27K is a standard value) or change R1 to 43K0 for 5.0 Volt output. (43 K is a standard value) A standard 0805 size resistor fits precisely, how convenient ;-). Make sure the other resistor is really 8.2K because that determines the feedback ratio. This way you can not burn up your circ...

Today the first LoRa modules arrived. I will be hooking these things up to a new board I am working on, it also contains a W7500P from wiznet (a cortex m0 with ethernet/IP/TCP stack inside) I Chose the complete LoRaWan implementation module from microchip to get started quickly. It communicates using a serial port using readable ASCII commands to the controlling MCU. Next step is making a break out board for this thing, it looks big but is only about 26.7 mm long and 3.3 mm thick. I will keep you updated. What is its use? It can communicate over RF (868 MHz) using LoRa protocol, using very little energy and over a very long range (10 km??) I am working on a easy to install sound-level and energy-monitoring/control system and think these modules can solve a piece of my very complex puzzle. It appears everyone in the world is jumping on the bandwagon right now to enable this IoT stuff, but real results and implementations are hard to find. If you need something like this, ...

Theo Kleijn has his laser cutter setup and it was time to make something useful. Theo's blog :  http://pa0kn.nl/#home I took a board I had laying around, a 16 relay board, similar to one found here :  http://www.ebay.com/itm/16-Channel-12V-Relay-Module-Coupling-Optocoupler-High-Trigger-For-MCU-Arduino-/221358546298 and  http://www.miniinthebox.com/16-channel-12v-relay-module-board-w-power-lm2576-optocoupler-protection_p903439.html And decided to make a nice base for it, so it was not directly on the table. I started by designing the base plate, I measured the board and made a drawing in LibreCad, which was in the Ubuntu repository. This was not a success, when trying to save the file the program segfaulted and all my work was lost. I already had a license for QCAD 2.2 (on which LibreCad is based) and have used it without problems on my old linux machines (in 2008 and later). The old version I had was alright, many productive shortcut-keys etc, but many impr...