Adjustable gain LNA
Low noise amplifiers are very useful. I built one with single BFG425W transistor with adjustable bias current. The schematic diagram is very simple:
LNA schematic diagram
and the PCB is 20x24mm:
LNA PCB
Smart nesting box
Smart nesting box is small wooden box for nesting birds. It is equipped with the live camera feed and some sensors. Four smart nesting boxes were made and three of them were placed in the wild. One was inhabited with the great tit in te early march 2017. After that, the bird laid 11 eggs. The bird then incubated eggs for 12 days. On the Easter Monday, the first shells cracked and newborns started poping out of the eggs.
I prepared the whole project for local school. The nesting boxes were made by 8 children aged from 11 to 14 during afternoon classes. It was great fun and the young scientists learned many new skills from electronics, materials, hand tools, crafting, programming, components, circuit design, biology, photography, physics, etc… The nesting box is described in detail here with all necessary production steps. Contact for further info is m@v4.si. The three nesting boxes placed in the wild have…
live video feed and sensor readouts available H E R E.
Raspberry Pi breakout board with ESD, PoE and Cortex M0
This is Raspberry Pi GPIO connector breakout board with some additional features:
- “Real” or “passive” PoE with 12V output
- 5V DC/DC module
- Additional 3,3V regulator
- ESD protection on all GPIO pins
- two additional pins for each pin on R.Pi 40 pin GPIO connector
- Separate UART and I2C headers
- 3,3V Supply for periphery is selectable: from R.Pi or from external regulator
- STM32F070 or similar in TSSOP-20 housing for controlling additional sensor or any other hardware
- Jumper for Cortex-M0 / R.Pi UART connection
First prototype
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Simple Rh, T and p sensor with UART communication
The Pressure, temperature and humidity sensor based on MS5637 HDC1080 originally (Rev. 2) operates via RS485 interface and multidrop HDLC-like protocol. I decided to simplify this for use with Raspberry Pi, arduion or any other mass platforms. First, I took away the RS485 transceiver and second, I simplified the communication.
First adaptation was easy:
Remove RS485 driver and connect Rx/Tx to A/B
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Pressure, temperature and humidity sensor based on MS5637 HDC1080 Rev.2
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
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Tiltable housing for Raspberry pi camera
The second version (here is larger 1st version with fixed angle) of R.Pi camera housing is smaller with 9 LEDs and possibility to adjust camera angle.
Adjustable housing with 9 LEDS for IR illumination
The 3D models are available on 3DcontentCentral or in GrabCad.
STL for 3D printing is on Thingiverse.
Raspberry pi camera housing
This is housing for R.Pi camera V2 with LED illumination.
Camera housing
It is 3D printable housing and PCB with 9 IR LEDs with enable.
Call URL with keypress on Raspberry Pi
Here is scenario:
pushbutton is connected to Raspberry Pi GPIO pin. Whet button is pressed, R.pi calls remote URL.
This can be useful for many simple applications, like detecting and timestamping passes at certain location.
The R.pi should be up and running. Connect the pushbutton to free GPIO. In our example we connected the button to pin 11. The pin is configured with the pullup, which means the button must pull the GPIO pin to ground. Pin 12 on r.Pi model 2B (40 pin P1) is GND:
Ultra simple schematic for this example
Now prepare some simple script on your fancy web browser, which will be called when someone presses the button. Here is example, which simply adds one line with time and date at the end of the file “log.txt” every time when file is loaded:
Simple HF amplifier for QRSS beacon
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.
Quadruple BDC motor driver for robotics
Once finished (deadline is end of January) this project will become open-source software and hardware.
My quadruple BDC driver for supports up to 4 brushed motors with encoders. Each motor is controlled by its individual closed loop and individual PID gain settings. Additionally, motor speed can also be individually addressed. Analog part of the driver is based on DRV8701P predriver and is controlled by STM32F4 microcontroller.
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