Silicon ChipA reliable solar lighting system - January 2021 SILICON CHIP
  1. Outer Front Cover
  2. Contents
  3. Publisher's Letter: More articles than space - a good problem to have!
  4. Mailbag
  5. Feature: Automotive Electronics, Part 2 by Dr David Maddison
  6. Project: AM/FM/SW Single-Chip Digital Radio by Charles Kosina
  7. Review: Altium 365 and Altium Designer 21 by Tim Blythman
  8. Project: MiniHeart: A Miniature Heartbeat Simulator by John Clarke
  9. Feature: How to use the MPLAB X Development Environment by Tim Blythman
  10. Serviceman's Log: One good turn deserves another by Dave Thompson
  11. Project: The Bass Block Subwoofer by Nicholas Dunand
  12. Circuit Notebook: A reliable solar lighting system by K. G.
  13. Circuit Notebook: Converting a cheap welder to a high-current battery charger by John Russull
  14. Circuit Notebook: Radiating test antenna for AM radios by Ian Batty
  15. Project: Busy Loo Indicator by John Chappell
  16. Feature: AVR128DA48 and Curiosity Nano Evaluation Board by Tim Blythman
  17. Product Showcase
  18. Vintage Radio: 1963 Philips Musicmaker MM1 mantel radio by Associate Professor Graham Parslow
  19. PartShop
  20. Feature: El Cheapo Modules: Mini Digital AC Panel Meters by Jim Rowe
  21. Ask Silicon Chip
  22. Market Centre
  23. Advertising Index
  24. Notes & Errata: Balanced Input Attenuator for the USB SuperCodec, November-December 2020; Two LED Christmas Stars, November 2020; D1 Mini LCD BackPack, October 2020
  25. Outer Back Cover

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

You can view 0 of the 112 pages in the full issue.

For full access, purchase the issue for $10.00 or subscribe for access to the latest issues. You can also log in if you are already a subscriber.

Articles in this series:
  • Automotive Electronics, Part 1 (December 2020)
  • Automotive Electronics, Part 2 (January 2021)
Items relevant to "AM/FM/SW Single-Chip Digital Radio":
  • AM/FM/SW Single-Chip Digital Radio PCB [CSE200902A] (AUD $10.00)
  • Pulse-type rotary encoder with pushbutton and 18t spline shaft (Component, AUD $3.00)
  • PCB-mount right-angle SMA socket (Component, AUD $3.00)
  • 16x2 Alphanumeric serial (I²C) LCD module with blue backlight (Component, AUD $7.50)
  • Firmware for the AM/FM/SW Single-Chip Digital Radio (Software, Free)
  • AM/FM/SW Single-Chip Digital Radio PCB pattern (PDF download) [CSE200902A] (Free)
  • Cutting diagrams and front panel artwork for the AM/FM/SW Single-Chip Digital Radio (PDF download) (Free)
Items relevant to "MiniHeart: A Miniature Heartbeat Simulator":
  • MiniHeart PCB [01109201] (AUD $5.00)
  • PIC12F617-I/P programmed for the MiniHeart [0110920A.HEX] (Programmed Microcontroller, AUD $10.00)
  • MiniHeart SMD parts (Component, AUD $5.00)
  • Firmware for the MiniHeart [01109201A.hex] (Software, Free)
  • MiniHeart PCB pattern (PDF download) [01109201] (Free)
  • Cutting diagrams and front panel artwork for the MiniHeart (PDF download) (Free)
Items relevant to "The Bass Block Subwoofer":
  • Cutting diagrams for the Bass Block (PDF download) (Panel Artwork, Free)
Items relevant to "Busy Loo Indicator":
  • Busy Loo Indicator PCB [16112201] (AUD $2.50)
  • Busy Loo Indicator PCB pattern (PDF download) [16112201] (Free)
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)

Purchase a printed copy of this issue for $10.00.

CIRCUIT NOTEBOOK Interesting circuit ideas which we have checked but not built and tested. Contributions will be paid for at standard rates. All submissions should include full name, address & phone number. A reliable solar lighting system The steps to my shed do not all have the same tread depth and riser height. I am used to them, but I still have some difficulty on moonless nights. A few years ago, when solar-powered garden lights became available cheaply, I bought a few of them and poked them into the ground alongside the steps, and I could finally see the steps at night. The problem is, these things are only made to have a life of about 12 months if you’re lucky, and soon they needed repair or replacement. After going through a couple of repair/replacement iterations, I decided that I needed a more permanent solution. I had collected a few 18650-size Li-ion cells which still seemed to have some life left, so I decided to use these in a lighting system for the steps. I needed to mount the actual lights on something solid so they wouldn’t be destroyed by a brush-cutter. I mounted the LEDs in a length of rectangular steel tube from a discarded swing set. I mounted this so that it also formed a handrail for the steps using tubular steel supports concreted into the ground with welded brackets. The four LEDs came from a defunct garden light. Once they were mounted siliconchip.com.au to the underside of the handrail, I ran a cable into the shed. The accompanying circuit diagram shows the solar panel, battery charger and battery manager for the lights. The circuit switches on the lights at nighttime but switches them off once the battery is flat. The solar panel is a 10W, 12V type left over from a previous project, already mounted on the shed roof. The XL6009 buck-boost regulator module reduces the voltage from the solar panel to the 5V required to run the TP4056-based Li-ion battery charger. The low voltage cut-off circuit below prevents damage to the Li-ion cells from over-discharge. Op amp IC1a acts as a voltage comparator with the reference coming from VREF1, an LM385BZ. This device only requires tens of microamps to operate and produces an accurate 1.2V which is fed to pin 2 of IC1a. Its other input pin samples the battery voltage via a 120kW/100kW divider. When the battery voltage falls to 2.7V, the output of IC1a goes low and so NPN transistor Q2 switches off. The gate of Mosfet Q1 is then pulled up to its source voltage by the 100kW resis- Australia’s electronics magazine tor, so Q1 turns off, preventing current from flowing from the battery to the LEDs. About 200mV of hysteresis is built into the switching point by the 560kW positive feedback resistor. The LEDs are also switched off during the day due to the action of NPN transistor Q3. When the solar panel voltage rises above about 1.2V, Q3’s base-emitter junction is forwardbiased, and so it switches on, pulling the battery-related voltage at pin 3 of IC1a low, close to 0V. This is sensed by IC1a as if the battery is flat, so again it switches the LEDs off. The rest of the time (ie, when the battery is above 2.7V and the solar panel is in darkness), the LEDs are connected across the battery and so they light up. The garden light LED modules incorporate current-limiting resistors to prevent them burning out with a fully charged (4.2V) battery, not shown on the circuit diagram. Note that Q1 was chosen so that it would present a low channel resistance with its gate at -2.7V compared to its source, ie, just before the low-battery cutout activates. It must also have a sufficiently low on-resistance to avoid getting too hot (~20mW in this case). K. G., One Tree Hill, SA. ($80) January 2021  75