Silicon ChipLatching output for Remote Monitoring Station - April 2021 SILICON CHIP
  1. Outer Front Cover
  2. Contents
  3. Publisher's Letter: Adobe making our lives difficult
  4. Mailbag
  5. Feature: Digital Radio Modes - Part 1 by Dr David Maddison
  6. Project: Digital FX (Effects) Pedal - Part 1 by John Clarke
  7. Project: Refined Full-Wave Motor Speed Controller by John Clarke
  8. Serviceman's Log: I hope the purists won't spit their dummies by Dave Thompson
  9. Circuit Notebook: Biofeedback for stress management by David Strong
  10. Circuit Notebook: Latching output for Remote Monitoring Station by Geoff Coppa
  11. Circuit Notebook: Alternative switched attenuator for Shirt Pocket Oscillator by Rick Arden
  12. Circuit Notebook: Follow-up to 'constant' AC source by Mauri Lampi
  13. Feature: The History of Videotape - Helical Scan by Ian Batty, Andre Switzer & Rod Humphris
  14. Project: High-Current Four Battery/Cell Balancer - Part 2 by Duraid Madina
  15. PartShop
  16. Project: Arduino-based MIDI Soundboard - Part 1 by Tim Blythman
  17. Product Showcase
  18. Review: Wagner cordless soldering iron by Tim Blythman
  19. Vintage Radio: 1948 Philips table model 114K by Associate Professor Graham Parslow
  20. Ask Silicon Chip
  21. Market Centre
  22. Advertising Index
  23. Notes & Errata: High-Current Battery Balancer, March 2021; Arduino-based Adjustable Power Supply, February 2021; LED Party Strobe Mk2, August 2015
  24. Outer Back Cover

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

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Items relevant to "":
  • Firmware (BAS and HEX) files for the DAB+/FM/AM Radio project (Software, Free)
Articles in this series:
  • Digital Radio Modes - Part 1 (April 2021)
  • Digital Radio Modes – Part 2 (May 2021)
Items relevant to "Digital FX (Effects) Pedal - Part 1":
  • Digital FX Unit PCB (potentiometer-based version) [01102211] (AUD $7.50)
  • Digital FX Unit PCB (switch-based version) [01102212] (AUD $7.50)
  • 24LC32A-I/SN EEPROM programmed for the Digital FX Unit [0110221A.HEX] (Programmed Microcontroller, AUD $10.00)
  • PIC12F1571-I/SN programmed for the Digital FX Unit with potentiometer [0110221B.HEX] (Programmed Microcontroller, AUD $10.00)
  • Spin FV-1 digital effects IC (SOIC-28) (Component, AUD $40.00)
  • Firmware for the Digital FX Unit [0110221A.HEX] (Software, Free)
  • Digital FX Unit PCB patterns (PDF download) [01102211-2] (Free)
Articles in this series:
  • Digital FX (Effects) Pedal - Part 1 (April 2021)
  • Digital FX (Effects) Pedal – Part 2 (May 2021)
Items relevant to "Refined Full-Wave Motor Speed Controller":
  • Refined Full-Wave Motor Speed Controller PCB [10102211] (AUD $7.50)
  • PIC12F617-I/P programmed for the Refined Full-Wave Motor Speed Controller [1010221A.HEX or 1010221B.HEX] (Programmed Microcontroller, AUD $10.00)
  • Hard-to-get parts for the Refined Full-Wave Motor Speed Controller (Component, AUD $60.00)
  • Firmware for the Refined Full-Wave Motor Speed Controller [1010221A.HEX] (Software, Free)
  • Refined Full-Wave Motor Speed Controller PCB pattern (PDF download) [10102211] (Free)
  • Cutting diagrams and lid panel artwork for the Refined Full-Wave Motor Speed Controller (PDF download) (Free)
Articles in this series:
  • The History of Videotape – Quadruplex (March 2021)
  • The History of Videotape - Helical Scan (April 2021)
  • The History of Videotape – Cassette Systems (May 2021)
  • The History of Videotape – Camcorders and Digital Video (June 2021)
Items relevant to "High-Current Four Battery/Cell Balancer - Part 2":
  • High Current Battery Balancer PCB [14102211] (AUD $12.50)
  • ATSAML10E16A-AUT programmed for the High-Current Battery Balancer [1410221B.HEX] (Programmed Microcontroller, AUD $15.00)
  • Firmware for the High-Current Battery Balancer [1410221B.HEX] (Software, Free)
  • High Current Battery Balancer PCB pattern (PDF download) [14102211] (Free)
Articles in this series:
  • High-Current Four Battery/Cell Balancer (March 2021)
  • High-Current Four Battery/Cell Balancer - Part 2 (April 2021)
Items relevant to "Arduino-based MIDI Soundboard - Part 1":
  • 64-Key Arduino MIDI Shield PCB [23101211] (AUD $5.00)
  • 8x8 Tactile Pushbutton Switch Matrix PCB [23101212] (AUD $10.00)
  • Simple Linear MIDI Keyboard PCB [23101213] (AUD $5.00)
  • Firmware for the 64-Key Arduino MIDI Matrix (Software, Free)
  • Software for the Arduino MIDI Shield & 8x8 Key Matrix plus 3D keycap model (Free)
  • 64-Key Arduino MIDI Shield PCB pattern (PDF download) [23101211] (Free)
  • 8x8 Tactile Pushbutton Switch Matrix PCB pattern (PDF download) [23101212] (Free)
  • Simple Linear MIDI Keyboard PCB pattern (PDF download) [23101213] (Free)
Articles in this series:
  • Arduino-based MIDI Soundboard - Part 1 (April 2021)
  • Arduino-based MIDI Soundboard – Part 2 (May 2021)
  • Simple Linear MIDI Keyboard (August 2021)

Purchase a printed copy of this issue for $10.00.

Latching output for Remote Monitoring Station This simple circuit adds extra capabilities to the 4G Remote Monitoring Station (February 2020; siliconchip. com.au/Article/12335). It provides a way for the Remote Monitoring Station to drive the Opto-Isolated Mains Relay (October 2018; siliconchip.com. au/Article/11267). I wanted to be able to switch an appliance on or off by sending an SMS. As the Monitoring Station project has a battery-saving feature, the status of the Arduino output pins is lost when the Arduino goes to sleep. This circuit adds a way to preserve the state without increasing the current consumption very much. However, in my case, mains power is available so that is not a significant concern. This circuit is based on a 555 timer which is used as a flip flop to switch the relay on and off. It keeps it in the last state, even when the Arduino is in sleep mode. When the circuit is first powered up, pin 2 of IC1 is held high via the 10kW pull-up resistor, while pin 6 is kept low by a 10kW pull-down resistor. The pin 4 reset input is briefly pulled low by the 10kW/100nF RC network. This ensures that the 555 won’t switch the appliance on after blackouts or power glitches. The Remote Monitoring Station code needs to be modified (as per the instructions in Ask Silicon Chip, March 2020) to send the selected Arduino pin high when you want the appliance switched on. The code also needs to be modified to send another Arduino pin high when you want the appliance to switch off. The selected switch-on pin connects to the base of the NPN transistor Q1 via a diode and 22kW resistor. When this pin goes high, it switches Q1 on, pulling pin 2 of IC1 low and thereby bringing its output pin 3 high. This powers the appliance up via the Opto-Isolated Mains Relay. The 555 will stay in this state when the Arduino goes to sleep. When the Arduino receives a command to switch off, the other pin going high pulls pin 6 of IC1 high, bringing its output pin 3 low, which switches the appliance off. The diodes on the inputs isolate the Arduino from the circuit and ensure that the circuit will only respond to logic high output levels. Geoff Coppa, Toormina, NSW. ($60) Alternative switched attenuator for Shirt Pocket Oscillator I am building the Shirt-Pocket Sized Audio DDS Oscillator (September 2020; siliconchip.com.au/Article/14563) in a 100 x 70 x 50mm aluminium box, using AA batteries for power and RCA and binding post outputs. This circuit shows the switched attenuator I will be using, which is different from the one suggested in the article. It uses a centre-off switch that I already had, which is smaller and easier to fit securely than a rotary switch. The ranges are not sequential, which is not ideal, but at least the middle position has the lowest output level. The need for the 150kW resistor is debatable, given the tolerance of the potentiometer resistance, but it does give an 11.111kW resistance in parallel with 12kW, which is the exact value needed. Rick Arden, Gowanbrae, Vic. ($60) 62 Silicon Chip Australia's Australia’s electronics magazine siliconchip.com.au