Contact: info@pavlin.si
Archive for the ‘Ham’ Category.
Gal ordered some PCBs from PCB-Way a while ago. It was multiproject panel with several PCBs. One of the modules was double sided revision of the Pressure, temperature and humidity sensor based on MS5637 HDC1080 which was posted while ago.
Pressure, temperature and humidity sensor based on MS5637 HDC1080
Continue reading ‘Pressure, temperature and humidity sensor based on MS5637 HDC1080 Rev.2’ »
This is 5 minutes soldering project. There is no schematic, just simple circuit, something between “dead bug” and conventional PCB design. I did this in two steps. First attempt was complete failure. Local OM told me that any power mosfet can operate as power amplifier for HF. Ok, maybe not just any. I tested with couple of them including IRFZ24N. Finaly I took “proper” MOSFET for higher frequency and the circuit worked pretty good:
Simple output stage for QRSS beacon assembled in “mixed” technology
I will briefly describe this quick and simple project and I hope readers would enjoy it.
USB/RS485 module on a single sided board worked successfully for several months. The code is now stable and I decided to order small batch of double sided PCBs for this project. Here is documentation:
RS485/USB interface on a double sided board
Continue reading ‘USB/RS485 converter on a double sided PCB’ »
This is another sensor in weather-sensor series. It is based on silabs Si1133.
Schematic:
Si1133 Sensor schematic with RS485 interface
This is anothe small module to measure air pressure, temperature and humidity. Two sensors are on-board: MS5637 and HDC1080. Microcontroller is small cortex M0 in TSSOP-20 housing from STM: STM32F070CxP. The SN65HVD72DGKR provides RS485 interface functionality with half duplex mode. Voltage regulator, reverse polarity protection and some LED indicators are provided on-board. Complete module is 10x55mm, produced on single-sided PCB, easily producible in every home lab with proto-PCB capability.
RH, T and air pressure sensor with RS485
Continue reading ‘Pressure, temperature and humidity sensor based on MS5637 HDC1080’ »
Testing of sensors with RS485 using PC without proper interface is not possible. Since RS232 interfaces are very rare, the interface should be hooked to USB. The interface between USB and RS485 can be soldered with one of the many FTDI interfaces with added RS485 driver, or bought as assembled module. There is always the third option. I made it from scratch.
I took smallest STM32F0 with USB and UART interface. The best thing with UART in the STM32F0 is that signal for driver enable is provided within hardware. The complete pinout of the microcontroller is:
I got samples of Si7013.
The Si7013 I2C Humidity and 2-Zone Temperature Sensor is a monolithic CMOS IC integrating humidity and temperature sensor elements, an analog-to-digital
converter, signal processing, calibration data, and an I2C Interface. The patented use of industry-standard, low-K polymeric dielectrics for sensing humidity enables the construction of low-power, monolithic CMOS Sensor ICs with low drift and hysteresis, and excellent long term stability. The humidity and temperature sensors are factory-calibrated and the calibration data is stored in the on-chip non-volatile memory. This ensures that the sensors are fully interchangeable, with no recalibration or software changes required. An auxiliary sensor input with power management can be tied directly to an external thermistor network or other voltage-output sensor. On-board logic performs calibration/linearization of the external input using user-programmable coefficients. The least-significant bit of the Si7013’s I2C address is programmable, allowing two devices to share the same bus. The Si7013 is available in a 3×3 mm DFN package and is reflow solderable. The
optional factory-installed cover offers a low profile, convenient means of protecting the sensor during assembly (e.g., reflow soldering) and throughout the life of the product, excluding liquids (hydrophobic/oleophobic) and particulates. The Si7013 offers an accurate, low-power, factory-calibrated digital solution ideal for measuring humidity, dew-point, and temperature, in applications ranging from HVAC/R and asset tracking to industrial and consumer platforms.
I prepared prototyping board with STM32F0 and line RS485 driver:
Continue reading ‘SiLabs Si7013 humidity and temperature sensor’ »
Affordable precision pluviometer PART 1 (introduction and construction) is here.
Here are first analog measurements of the affordable precision pluviometer:
| mL | uV | uV/mL |
| 0 | 550 | |
| 10 | 568 | |
| 30 | 606 | 1.87 |
| 50 | 643 | 1.86 |
| 100 | 736 | 1.86 |
| 200 | 924 | 1.87 |
| 300 | 1109 | 1.86 |
| 400 | 1296 | 1.87 |
| 500 | 1483 | 1.87 |
| 600 | 1672 | 1.87 |
| 650 | 1762 | 1.86 |
| 700 | 1853 | 1.86 |
| 750 | 1949 | 1.87 |
The measurement setup was: measuring graduated cylinder (4) strain gauge sensor (3) from kitchen scale, power suuply (2) and digital multimeter (1):
Continue reading ‘Affordable pluviometer part 2 – strain gauge measurements’ »
Somewhere in year 1995 I had idea for anemometer without movable parts. I forgot about that and recently I started building weather station for the vine yard. Now it’s time to transfer that idea to reality.This is the sketch from that time:
I am working in company HYB in R&D department. My experience with pressure sensors is longer than the anemometer idea (more than 20 years). Our main products are sensors. We have industrial pressure sensors for extremely low pressures. Lowest full scale pressure sensor goes as low as 1mbar (one millibar!). Just for impression: this is equal to 1cm of water column – one cm under the water surface is 1mbar pressure. The model, most suitable for annemometer based on wind pressure measurement is HPSD 3000:
The sensor has 15 bits I2C output for pressure and temperature via I2C interface. The sensor is available through our distributor or ask directly here.
The white plastic radiation shields that protect the temperature, humidity and other sensitive sensors from any direct sunlight can be built for bargain. I started with trays from local garden shop. They sell for about 10 cents per tray with diameter 120mm (5 inches). About 10 trays were CNC machined:
Continue reading ‘Low cost sun shield for weather sensors’ »
