Silicon ChipAlternative PCB joiner for Linear MIDI Keyboard - January 2022 SILICON CHIP
  1. Outer Front Cover
  2. Contents
  3. Publisher's Letter: Risk aversion stifles innovation
  4. Mailbag
  5. Subscriptions
  6. Feature: All About Batteries - Part 1 by Dr David Maddison
  7. Project: Two Classic LED Metronomes by Randy Keenan
  8. Review: Dick Smith Autobiography by Nicholas Vinen
  9. Feature: Solar Power with Batteries by Dr Alan R. Wilson
  10. Project: Multi-Channel Speaker Protector by Phil Prosser
  11. Product Showcase
  12. Circuit Notebook: Conway's Game of Life on the Micromite by Kenneth Horton
  13. Circuit Notebook: Alternative PCB joiner for Linear MIDI Keyboard by Tim Blythman
  14. Circuit Notebook: Compact reed relay module by Gianni Pallotti
  15. Project: The Raspberry Pi-based PicoMite by Geoff Graham & Peter Mather
  16. Feature: El Cheapo Modules: LTDZ Spectrum Analyser by Jim Rowe
  17. Vintage Radio: The Mysterious Mickey Oz by Ian Batty
  18. Serviceman's Log: Designing for unrepairability by Dave Thompson
  19. Project: Remote Control Range Extender by John Clarke
  20. PartShop
  21. Ask Silicon Chip
  22. Market Centre
  23. Advertising Index
  24. Notes & Errata: SMD Trainer, December 2021; Hummingbird Amplifier, December 2021; Pocket Weather Station, November 2021
  25. Outer Back Cover

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Articles in this series:
  • All About Batteries - Part 1 (January 2022)
  • All About Batteries – Part 2 (February 2022)
  • All About Batteries, part three (March 2022)
Items relevant to "Two Classic LED Metronomes":
  • 8-LED Classic Metronome PCB [23111211] (AUD $5.00)
  • 10-LED Classic Metronome PCB [23111212] (AUD $7.50)
  • Classic LED Metronome PCB patterns (PDF download) [23111211-2] (Free)
  • Dial labels and drilling guide for the Two Classic LED Metronomes (Panel Artwork, Free)
Articles in this series:
  • Home Solar Panel Electricity: Is It Worth It? (May 2015)
  • Solar Power with Batteries (January 2022)
Items relevant to "Multi-Channel Speaker Protector":
  • 6-way Loudspeaker Protector PCB [01101221] (AUD $7.50)
  • 4-way Loudspeaker Protector PCB [01101222] (AUD $5.00)
  • Multi-Channel Speaker Protector PCB patterns (PDF download) [01101221-2] (Free)
Items relevant to "Conway's Game of Life on the Micromite":
  • Firmware & PCB files for Conway's Game of Life on the Micromite (Software, Free)
Items relevant to "Alternative PCB joiner for Linear MIDI Keyboard":
  • Simple Linear MIDI Keyboard Joiner PCB [23101214] (AUD $1.00)
Items relevant to "Compact reed relay module":
  • Gerber files for the Reed Relay Module (Software, Free)
Items relevant to "The Raspberry Pi-based PicoMite":
  • Firmware for the PicoMite (Software, 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)
  • MOS Air Quality Sensors (June 2022)
Items relevant to "Remote Control Range Extender":
  • Remote Control Range Extender IR-to-UHF PCB [15109212] (AUD $2.50)
  • Remote Control Range Extender UHF-to-IR PCB [15109211] (AUD $2.50)
  • PIC12F617-I/P programmed for the Remote Control Range Extender (UHF to IR part) [1510921A.HEX] (Programmed Microcontroller, AUD $10.00)
  • PIC10LF322-I/OT programmed for the Remote Control Range Extender (UHF transmitter part) [1510921M.HEX] (Programmed Microcontroller, AUD $10.00)
  • Kit for the Remote Control Range Extender IR-to-UHF adaptor (Component, AUD $25.00)
  • Software for the Remote Control Range Extender (Free)
  • Remote Control Range Extender PCB patterns (PDF download) [15109211-2] (Free)
  • Lid panel label artwork and box drilling diagrams for the Remote Control Range Extender (Panel Artwork, Free)

Purchase a printed copy of this issue for $11.50.

Alternative PCB joiner for Linear MIDI Keyboard Since designing the Linear MIDI Keyboard (August 2021; siliconchip. com.au/Article/14997), we realised there is another way to join the PCBs. The cut-down pin headers described in that article are inexact and tricky to fit, so we designed a small PCB to make it easier. We wrote that the pin headers should be fitted before the switches, but the Joiners are much easier to work with, allowing fully assembled Keyboard PCBs to be joined. Two of these Joiner PCBs are needed to join a pair of Keyboard PCBs; this means a total of 14 Joiner PCBs for a full 64-note Keyboard. The Joiner PCBs have a tight solder mask on one side to stop the solder spreading and bridging the pads, so this side should be against the Keyboard PCBs. The side with large solder pads goes on the outside. Place the Joiner PCB onto the Keyboard PCB. It should line up with the edges of the silkscreen printing on the Keyboard PCB. Like any surface mounted part, tack one pad to correctly locate the Joiner and adjust as needed. Unlike the pin header, you can apply the iron from directly above. Feed a generous amount of solder into each pad hole. Surface tension should pull the solder into the hole and onto the pad, as long as all surfaces are parallel and flush against each other. Gently flip the Keyboard PCBs over and repeat for the other side using a second Joiner. Now test for continuity between adjacent PCBs. The pads on CON1, CON3 and CON5 should bell out in sequence, while those on CON2 and CON4 will match and also should connect to different pads on CON6. If you are unsure, you can also check the troubleshooting tips at the end of the MIDI Keyboard article. Tim Blythman, Silicon Chip. Compact reed relay module Most of the relay modules available on the internet, although quite inexpensive, are very large due to uncertain voltage and current requirements. I needed something smaller, suitable for use on a breadboard. As many relays have very short pins, the only option was to design my own module. Reed relays are my best option, not only because of their small size, but also for their characteristics. Reed relays have hermetically-sealed contacts, protected against possible oxidation. They also provide more consistent switching at low signal levels, requiring less power to operate and with a better on-resistance. This is because reed relays use the magnetic field from the coil to pull sets of ferromagnetic reed switch contacts together, which are already in very close proximity. Thus they do not need a larger and more complicated armature arrangement. The relay module has four reed relays in 4-pin SIL packages along with SMD driver transistors, hidden on the underside, plus a set of telltale LED indicators. The driver base resistors and LED current-limiting resistors are also SMD parts, keeping siliconchip.com.au the module very compact. The two sets of relay contacts and the driving connections are each broken out to 4-pin headers, while power is supplied to the module via a 2-pin Australia's electronics magazine header. EAGLE and Gerber files for the PCB are available from siliconchip. com.au/Shop/6/6084 Gianni Pallotti, North Rocks, NSW. ($75) January 2022  63