Silicon ChipAnimal and pest repeller - 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)
  • MOS Air Quality Sensors (June 2022)
  • PAS CO2 Air Quality Sensor (July 2022)

Purchase a printed copy of this issue for $10.00.

Animal and pest repeller A family cat always clawing my prized speaker, a dog constantly marking an area and a possum chewing off my seedlings were problems that I needed to solve. I designed this circuit to deter their actions. A common fear for the animals is the sound of a spray can, so I designed this circuit to simulate the repetitive quick squirt of a can along with flashing red LED ‘eyes’. The PIR sensor module, PIR1 (Jaycar Cat XC4444) detects movement and sends out a high pulse with a duration based on the delay setting of the PIR detector. When this pulse is received, it switches on power to the rest of the circuit as it forward-biases the baseemitter junction of NPN transistor Q1. This, in turn, pulls current from the base of PNP transistor Q2, supplying 9V via its collector. If night-time only use is required, an LDR such as Jaycar Cat RD3485 or Altronics Cat Z1621 can be wired across the 1MW base-emitter resistor of Q1, as shown. This will prevent triggering during daytime by shunting Q1’s base drive current due to siliconchip.com.au its lower resistance when exposed to light. When the PIR is triggered, power is supplied to a multivibrator based around PNP transistors Q3 & Q6 and NPN transistors Q4 & Q5. This alternatively drives the LEDs via Q6’s collector, and the white noise circuitry via Q3’s collector. When current flows from Q3’s collector, white noise is generated by a reverse-biased small signal silicon transistor junction (Q7). This is then amplified by NPN transistor Q8, operating as a common-emitter amplifier, followed by audio amplifier IC1, which drives a miniature 8W speaker. I built the circuit into UB3 jiffy box with LEDs as the ‘eyes’, the PIR as the ‘nose’ and the speaker as the ‘mouth’. For best results, set the PIR sensor to single trigger mode and adjust its trimpots to almost minimum sensitivity and delay. A piezo speaker can be used instead of a standard speaker, but it will produce less volume. It will also reduce the overall current drawn from the 9V battery. Australia’s electronics magazine The majority of small-signal transistors will stop breaking down to produce white noise at 7.7V. Highfrequency types like the BF494 will operate down to 6.8V, so if the battery voltage drops below 8V, white noise won’t be generated. One solution is to place a 3V lithium cell in series with the 100kW resistor to Q7’s emitter, boosting the voltage. There is negligible current drawn from this cell. However, I found this wasn’t required with a good 9V battery. Overall battery drain is less than 100µA at idle, then up to 50mA when triggered if the amplifier is set to maximum volume via potentiometer VR1. The power switch is an SPDT centre-off type. The lower on position powers the PIR module only, to enable stabilisation which can take a minute. Then the switch is thrown over to the upper on position, which fully powers the circuit. As the PIR module has a wide view angle, it may be necessary to mask some areas off to achieve the required viewing angle. Warwick Talbot, Toowoomba, Qld. ($90) February 2021  71