Adventures of a Tech, avonturen van een techneut

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...

Just a short one. I bought one of these things. It can do 50 volt 5 Amp, I have not looked at the quality of the output (noise, overshoot all unknown to me)  but should be alright to control a lamp, a battery or a strip of LED's is my guess. You can easily control the current and voltage output using a serial port. (a usb-serial-rs485 was provided) I seems to talk modbus protocol. To change the baud rate and modbus-slave-address, keep POWER button pressed during power on, this will enter you into the configuration menu. register list here : Register Map for this device. Function Description Number of bytes Decimal places UNIT Read/Write Register address U-SET Voltage setting 2 2 V R/W 0000H I-SET Current setting 2 3 A R/W 0001H UOUT Output voltage display value 2 2 V R 0002H IOUT Output...

I got a second hand (but barely used) BF30 clone milling machine. The rpm meter was not working correctly (not showing high RPM, nonsense numbers) I investigated and found the photo interrupter on the spindle axle. It was covered in grease (sticky brown Chinese transport grease). After taking it apart I noticed all holes were over-sized (and slotted). Mounting the thing back and getting the perfect alignment would be a gamble (I like more precise work, but it appears all holes in this machine are too large or slotted, every edge is sharp and needs deburring). I made a little tool to check the workings, it is impossible to adjust once the motor is mounted so it has to be correct before I put the motor back on the machine. Here is the setup : The ring has 16 holes, so the rpm is more accurately (or quickly) determined. How this works : the system counts number of pulses in one second and from that displays the number of rpm ( NL: toerental in omwentelingen per minuut)...

Yesterday and some days before I did some experiments in testing the LoRa radio modules I have from microchip. The modules were connected to some laptops over USB serial. I wrote some python scripts to send data using the pyserial library. One laptop was sitting on a table indoors, no real antenna, just a piece of wire. The other laptop was outdoors, walking around, no real antenna, just a piece of wire. The spreading factor for LoRa was SF12, power was set to high. Further details available on request. (email me) This experiment was very successful, about 1 kilometer, good connection, no loss of data. In the picture above, Richard is holding the laptop and the RF module, we are about a kilometer away from TX and get perfect data, on the overpass above the A2 road. But when we got between a lot of buildings, the results were not that good. At 700 meter we lost connection. 500 meter was mostly fine. In Tilburg an experiment was done.. and 500 meter urban was not...

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, ...

Today I got a used APC UPS RS 1000, you know those things that should keep your system up and running when the power fails. The batteries where toasted, this happens to all these devices after about a year. Since new batteries only last a year and cost about $ 65 and can only keep your system up for a very short time I decided to hack something together. I got some brand new car batteries and hooked them up, (yes I included a fuse for safety) You might ask: "Do you really need a UPS in the Netherlands?"  Answer, "no, not really" but it is fun to have and since the UPS was free I now have some long lasting power. Here are some pictures. This is just a sort of useless nerdy fun. Power! the lights come on right away. OK, maybe 16 square mm wire is too much? General setup, 2 batteries and the UPS. And another picture. I will test the performance and add data later, I will leave this stuff loading the batteries for a few days.