Silicon ChipDIY laser rangefinder - February 2021 SILICON CHIP
  1. Outer Front Cover
  2. Contents
  3. Publisher's Letter: New computer technology
  4. Mailbag
  5. Feature: Radio Time Signals throughout the World by Dr David Maddison
  6. Feature: Follow-up: Quantum-dot Cellular Automata by Dr Sankit Ramkrishna Kassa
  7. Project: Battery Multi Logger by Tim Blythman
  8. Project: Arduino-based Adjustable Power Supply by Tim Blythman
  9. Serviceman's Log: A feline-themed cautionary tale by Dave Thompson
  10. Project: Electronic Wind Chimes by John Clarke
  11. Circuit Notebook: LCD clock and thermometer by Mahmood Alimohammadi
  12. Circuit Notebook: DIY laser rangefinder by Bera Somnath
  13. Circuit Notebook: Animal and pest repeller by Warwick Talbot
  14. Circuit Notebook: Stable multi-frequency sinewave generator by Petre Petrov
  15. Circuit Notebook: WiFi Snooping with a Raspberry Pi by Sid Lonsdale
  16. Feature: Making Android Apps with App Inventor by Roderick Wall
  17. Feature: Making a Compact Virtual Electronics Workbench by Tim Blythman
  18. Feature: Upgrading your Computer to the latest CPU by Nicholas Vinen
  19. PartShop
  20. Feature: El Cheapo Modules: LCR-T4 Digital Multi-Tester by Jim Rowe
  21. Vintage Radio: Philips 1952 BX205 B-01 AM/SW battery valve radio by Charles Kosina
  22. Ask Silicon Chip
  23. Market Centre
  24. Notes & Errata: Busy Loo Indicator, January 2021; Mini Digital AC Panel Meters, January 2021; Radiating test antenna for AM Radios, Circuit Notebook, January 2021; Vintage Battery Radio Li-ion Power Supply, December 2020; Colour Maximite 2, July-August 2020
  25. Advertising Index
  26. Outer Back Cover

This is only a preview of the February 2021 issue of Silicon Chip.

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Items relevant to "":
  • BWD602 Documents (Software, Free)
Items relevant to "Follow-up: Quantum-dot Cellular Automata":
  • QCA follow-up: Potential Energy Explanation (Software, Free)
Articles in this series:
  • Quantum-dot Cellular Automata (August 2019)
  • Follow-up: Quantum-dot Cellular Automata (February 2021)
Items relevant to "Battery Multi Logger":
  • Battery Multi Logger PCB [11106201] (AUD $5.00)
  • PIC16F1455-I/SL programmed for the Microbridge [2410417A.HEX] (Programmed Microcontroller, AUD $10.00)
  • PIC32MX170F256B-I/SO programmed for the Battery Multi Logger [1110620A.hex] (Programmed Microcontroller, AUD $15.00)
  • DS3231MZ real-time clock IC (SOIC-8) (Component, AUD $10.00)
  • DS3231 real-time clock IC (SOIC-16) (Component, AUD $7.50)
  • SMD resistor - 15mΩ ±1% M6332/2512 3W (CRA2512-FZ-R015ELF or similar) (Source component, AUD $2.00)
  • 2.8-inch TFT Touchscreen LCD module with SD card socket (Component, AUD $25.00)
  • Matte/Gloss Black UB3 Lid for 2.8-inch Micromite LCD BackPack (PCB, AUD $5.00)
  • Battery Multi Logger software [1110620A.hex] (Free)
  • Battery Multi Logger PCB pattern (PDF download) [11106201] (Free)
Articles in this series:
  • Battery Multi Logger (February 2021)
  • Battery Multi Logger - Part 2 (March 2021)
Items relevant to "Arduino-based Adjustable Power Supply":
  • Arduino-based Adjustable Power Supply PCB [18106201] (AUD $5.00)
  • SMD resistor - 15mΩ ±1% M6332/2512 3W (CRA2512-FZ-R015ELF or similar) (Source component, AUD $2.00)
  • MCP4251-502E/P dual 5kΩ digital potentiometer (Component, AUD $3.00)
  • Arduino-based Adjustable Power Supply Software (Free)
  • Arduino-based Adjustable Power Supply PCB pattern (PDF download) [18106201] (Free)
Articles in this series:
  • Making a Compact Virtual Electronics Workbench (February 2021)
  • Arduino-based Adjustable Power Supply (February 2021)
Items relevant to "Electronic Wind Chimes":
  • Electronic Wind Chimes PCB [23011201] (AUD $10.00)
  • PIC16F1459-I/P programmed for the Electronic Wind Chimes [2301120A.HEX] (Programmed Microcontroller, AUD $10.00)
  • Pair of CSD18534KCS logic-level Mosfets (Component, AUD $6.50)
  • Electronic Wind Chimes software [2301120A.hex] (Free)
  • Electronic Wind Chimes PCB pattern (PDF download) [23011201] (Free)
Articles in this series:
  • Electronic Wind Chimes (February 2021)
  • Electronic Wind Chimes - Part 2 (March 2021)
Items relevant to "LCD clock and thermometer":
  • Firmware for the LCD Clock and Thermometer (Software, Free)
Items relevant to "DIY laser rangefinder":
  • Firmware for the DIY Laser Rangefinder (Software, Free)
Items relevant to "WiFi Snooping with a Raspberry Pi":
  • Commands for WiFi Snooping with a Raspberry Pi (Software, Free)
Items relevant to "Making Android Apps with App Inventor":
  • TDR Android app (made using App Inventor) (Software, Free)
Items relevant to "Making a Compact Virtual Electronics Workbench":
  • Arduino-based Adjustable Power Supply PCB [18106201] (AUD $5.00)
Articles in this series:
  • Making a Compact Virtual Electronics Workbench (February 2021)
  • Arduino-based Adjustable Power Supply (February 2021)
Articles in this series:
  • El Cheapo Modules From Asia - Part 1 (October 2016)
  • El Cheapo Modules From Asia - Part 2 (December 2016)
  • El Cheapo Modules From Asia - Part 3 (January 2017)
  • El Cheapo Modules from Asia - Part 4 (February 2017)
  • El Cheapo Modules, Part 5: LCD module with I²C (March 2017)
  • El Cheapo Modules, Part 6: Direct Digital Synthesiser (April 2017)
  • El Cheapo Modules, Part 7: LED Matrix displays (June 2017)
  • El Cheapo Modules: Li-ion & LiPo Chargers (August 2017)
  • El Cheapo modules Part 9: AD9850 DDS module (September 2017)
  • El Cheapo Modules Part 10: GPS receivers (October 2017)
  • El Cheapo Modules 11: Pressure/Temperature Sensors (December 2017)
  • El Cheapo Modules 12: 2.4GHz Wireless Data Modules (January 2018)
  • El Cheapo Modules 13: sensing motion and moisture (February 2018)
  • El Cheapo Modules 14: Logarithmic RF Detector (March 2018)
  • El Cheapo Modules 16: 35-4400MHz frequency generator (May 2018)
  • El Cheapo Modules 17: 4GHz digital attenuator (June 2018)
  • El Cheapo: 500MHz frequency counter and preamp (July 2018)
  • El Cheapo modules Part 19 – Arduino NFC Shield (September 2018)
  • El cheapo modules, part 20: two tiny compass modules (November 2018)
  • El cheapo modules, part 21: stamp-sized audio player (December 2018)
  • El Cheapo Modules 22: Stepper Motor Drivers (February 2019)
  • El Cheapo Modules 23: Galvanic Skin Response (March 2019)
  • El Cheapo Modules: Class D amplifier modules (May 2019)
  • El Cheapo Modules: Long Range (LoRa) Transceivers (June 2019)
  • El Cheapo Modules: AD584 Precision Voltage References (July 2019)
  • Three I-O Expanders to give you more control! (November 2019)
  • El Cheapo modules: “Intelligent” 8x8 RGB LED Matrix (January 2020)
  • El Cheapo modules: 8-channel USB Logic Analyser (February 2020)
  • New w-i-d-e-b-a-n-d RTL-SDR modules (May 2020)
  • New w-i-d-e-b-a-n-d RTL-SDR modules, Part 2 (June 2020)
  • El Cheapo Modules: Mini Digital Volt/Amp Panel Meters (December 2020)
  • El Cheapo Modules: Mini Digital AC Panel Meters (January 2021)
  • El Cheapo Modules: LCR-T4 Digital Multi-Tester (February 2021)
  • El Cheapo Modules: USB-PD chargers (July 2021)
  • El Cheapo Modules: USB-PD Triggers (August 2021)
  • El Cheapo Modules: 3.8GHz Digital Attenuator (October 2021)
  • El Cheapo Modules: 6GHz Digital Attenuator (November 2021)
  • El Cheapo Modules: 35MHz-4.4GHz Signal Generator (December 2021)
  • El Cheapo Modules: LTDZ Spectrum Analyser (January 2022)
  • Low-noise HF-UHF Amplifiers (February 2022)
  • A Gesture Recognition Module (March 2022)
  • Air Quality Sensors (May 2022)

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DIY laser rangefinder I bought a TFMini lidar module intending to build a radar-like device, but then I realised that at work we spend a lot of time measuring the length of ERW pipes with measuring tapes. ERW (electrically resistant weld) pipes are 300mm plus in diameter and up to 12m long. They are used in our power plant for ash slurry transportation. It’s difficult to measure ERW pipes accurately. So I decided to create a device to accurately measure the length of pipe sections (to within 1cm) using the TFMini TOF (time-of-flight) laser module. Two varieties are available: the TFMini-S (US$35) and TFMini Plus (US$45); both have a serial interface. But the TFMini Plus has a wider measurement range (10-1200cm compared to 30-1200cm), can take 1000 measurements per second instead of 100 and is rated to operate from -20°C to +60°C rather than 0-60°C. Just placing the TFMini at one end of the pipe and directing it towards the edge plate will give accurate length reading. To increase the precision, I average a few readings. 70 Silicon Chip Both the TFMini-S and TFMini Plus have a viewing angle of 3.4°. Therefore, for long pipes, the aim is crucial to get a correct reading. To aid in this, I have incorporated a visible laser pointer with a push-on button (S2). It’s lined up with the TFMini module so you can see to where it measures. The TFMini works on reflection of invisible laser light from the surface of the object. In case the object does not reflect back or completely absorb or diffuse the incoming laser light, the reading will be erroneous. Such surfaces include water or slanted and highly reflective glass windows. For all other kinds of objects, the light gets reflected, and the measurement is correct. It’s accurate even with moving objects. Besides the TFMini module and laser pointer, my circuit uses an ESP32 microcontroller module, a 128x64 pixel OLED screen, two regulators, two capacitors and a battery. The OLED screen is an I2C device so it’s wired to the ESP32’s D21 and D22 I/O pins (just about any pins on the ESP32 can be used for I2C). As mentioned earlier, the TFMini uses serial, so it’s wired to the second UART on the ESP32. Australia’s electronics magazine A 3.3V low-dropout linear regulator (REG1) provides 3.3V to run the ESP32 and OLED display. The TFMini and the laser diode are supplied with 5V generated from a small boost module that runs off a single Li-ion or LiPo cell, with S1 provided for power switching. For use at my workplace, the device has to be portable so that my team can use it out in the field. That is why I ended up using a single LiPo cell and a boost module. It can also run from two 1.5V cells in series. The only real trick to assembling the unit is making sure that the TFMini and laser pointer are aimed at the same spot. To do this, set up a small object just under 12m away from your testing location, aim the TFMini at it until you get a sensible reading, adjust the laser pointer so that the dot is centred on that object and then fix the laser pointer in place. The ESP32 is programmed using the Arduino IDE. You can download the sketch and all the required libraries from siliconchip.com.au/Shop/6/5753 The libraries used are tfmini.h, Adafruit_GFX.h and Adafruit_SSD1306.h. Bera Somnath, Vindhyanagar, India. ($80) siliconchip.com.au