Silicon ChipAn easy way to measure SMDs - June 2022 SILICON CHIP
  1. Outer Front Cover
  2. Contents
  3. Publisher's Letter: Shutting down our old website
  4. Mailbag
  5. Feature: IC Fabrication, Part 1 by Dr David Maddison
  6. Project: Spectral Sound MIDI Synthesiser by Jeremy Leach
  7. Feature: Radar Coach Speed Detector by Allan Linton-Smith
  8. Project: Buck-Boost LED Driver by Tim Blythman
  9. Project: Arduino Programmable Load by Tim Blythman
  10. Project: 500W Power Amplifier, Part 3 by John Clarke
  11. Feature: MOS Air Quality Sensors by Jim Rowe
  12. Project: Revised Battery Charge Controller by John Clarke
  13. Review: Altium Designer 22 by Tim Blythman
  14. Circuit Notebook: RF burst power meter by George Mackiewicz
  15. Circuit Notebook: Artificial candle is ‘ignited’ by a real flame by Aarav Garg
  16. Circuit Notebook: Digital volume control using discrete logic by John Clarke & Raj. K. Gorkhali
  17. Circuit Notebook: An easy way to measure SMDs by Michael Harvey
  18. Serviceman's Log: Ion with the wind by Dave Thompson
  19. Vintage Radio: Admiral 19A11S TV by Dr Hugo Holden
  20. PartShop
  21. Ask Silicon Chip
  22. Market Centre
  23. Advertising Index
  24. Notes & Errata: 500W Power Amplifier pt2, May 2022; Model Railway Semaphore Signal, April 2022
  25. Outer Back Cover

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Items relevant to "":
  • PIC16F88 migration document (PDF) (Software, Free)
Articles in this series:
  • IC Fabrication, Part 1 (June 2022)
  • IC Fabrication, Part 2 (July 2022)
Items relevant to "Spectral Sound MIDI Synthesiser":
  • Spectral Sound MIDI Synthesiser PCB [01106221] (AUD $7.50)
  • Short form kit for the Spectral Sound MIDI Synthesiser (Component, AUD $200.00)
  • Software, firmware & documentation for the Spectral Sound MIDI Synthesiser (Free)
  • Spectral Sound MIDI Synthesiser PCB pattern (PDF download) [01106221] (Free)
  • Front & lid panel labels and drilling diagram for the Spectal Sound MIDI Synthesiser (Panel Artwork, Free)
Items relevant to "Buck-Boost LED Driver":
  • High Power Buck-Boost LED Driver PCB [16103221] (AUD $5.00)
  • 70W COB LED panel - cool white (6000-6500K) (Component, AUD $19.50)
  • 70W COB LED panel - warm white (3000-3200K) (Component, AUD $19.50)
  • Complete kit for the High Power Buck-Boost LED Driver (Component, AUD $80.00)
  • High Power Buck-Boost LED Driver PCB pattern (PDF download) [16103221] (Free)
Items relevant to "Arduino Programmable Load":
  • Arduino Programmable Load PCB [04105221] (AUD $5.00)
  • Firmware for the Arduino-based Programmable Load (Software, Free)
  • Arduino Programmable Load PCB pattern (PDF download) [04105221] (Free)
Items relevant to "500W Power Amplifier, Part 3":
  • 500W Amplifier Module PCB [01107021 RevD] (AUD $25.00)
  • Hard-to-get parts for the 500W Amplifier (Component, AUD $200.00)
  • 500W Amplifier Module PCB pattern (PDF download) [01107021] (Free)
Articles in this series:
  • Fan Controller & Loudspeaker Protector (February 2022)
  • Amplifier Clipping Indicator (March 2022)
  • 500W Power Amplifier, Part 1 (April 2022)
  • 500W Power Amplifier, Part Two (May 2022)
  • 500W Power Amplifier, Part 3 (June 2022)
Items relevant to "MOS Air Quality Sensors":
  • Sample sketches for MOS Air Quality Sensors (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)
  • PAS CO2 Air Quality Sensor (July 2022)
Items relevant to "Revised Battery Charge Controller":
  • Revised Intelligent Battery Charge Controller PCB [14107192] (AUD $7.50)
  • PIC16F88-I/P programmed for the Universal Battery Charge Controller [1410719A.HEX] (Programmed Microcontroller, AUD $15.00)
  • Relay - EA2-5NU (Component, AUD $3.00)
  • IPP80P03P4L-07 high-current P-channel Mosfet (Component, AUD $2.50)
  • Firmware and source code for the Universal Battery Charge Controller [1410719A.HEX] (Software, Free)
  • Revised Battery Charge Controller PCB pattern (PDF download) [14107192] (Free)
  • Universal Battery Charge Controller front panel artwork (PDF download) (Free)
Articles in this series:
  • Have you got a dumb battery charger in your garage? (December 2019)
  • Revised Battery Charge Controller (June 2022)
Items relevant to "RF burst power meter":
  • Firmware for the RF burst power meter (Software, Free)
Items relevant to "Artificial candle is ‘ignited’ by a real flame":
  • Firmware for the Artificial candle using a real flame (Software, Free)

Purchase a printed copy of this issue for $8.50.

down counter, IC4. The borrow output at pin 13 is usually high, so the pin 3 voltage level from IC1 is inverted by IC3c and then inverted again by IC3d. This causes the counter to decrement on the initial press of S1. If the counter’s output at Q0-Q3 reaches 0000, the borrow output goes low, forcing the IC3c output high and hence IC3d’s output goes low, preventing further decrementing. This is the negative ‘end stop’ which prevents the volume from jumping from maximum volume to minimum. A similar operation occurs with IC2 and NAND gates IC3a and IC3b. The difference is that the counter is incremented instead of decremented, and stops when outputs Q0-Q3 reach (1111) or minimum volume. Note that the counter counts down to increase volume and counts up to decrease volume. That’s because maximum volume (minimum attenuation) occurs when Q0-Q3 are all low. IC4 includes a preload feature, where the Q0 to Q3 outputs can be set to a particular value during power-up. Jumper links JP1-JP4 set the power-up volume level. If no jumpers are inserted, the preload inputs at P0 to P3 are all held high via 10kW resistors and the unit is at minimum volume (maximum attenuation). To determine the initial attenuation setting, take the binary number formed by jumpers JP1-JP4 (with a shorting block being 0 and open-circuit being 1), convert it to decimal and multiply it by three. This is the initial attenuation in dB. For example, with JP1 & JP3 in and JP2 & JP4 out, the binary number is 0101, five in decimal, and times three gives 15dB attenuation. Volume control The audio signal is applied to a buffer circuit (IC5a for the left channel) operating as a unity-gain amplifier. The op amp needs ±5V supplies which can be obtained from existing supplies in a preamplifier. Regulators may be required to reduce the voltages (eg, 7805 and 7905 types). The TL072 type op amps shown can handle signals up to about 2.5V RMS before clipping with such a supply. If you use rail-to-rail op amps instead, that would allow for signals up to about 3.5V RMS. You could also consider using lower distortion op amps. Do not use a higher supply voltage siliconchip.com.au since the following analog switches may be overdriven. The output from IC3 is applied to a 16-level attenuator controlled by the Q0-Q3 binary outputs from IC4. The attenuation is logarithmic, and we have set the range to be from zero attenuation down to 45dB attenuation in 3db steps. There are four attenuation stages. The first stage provides 24dB attenuation, the second stage, 12db, the third stage 6dB and the final stage, 3dB attenuation. With various combinations of these attenuators, we can obtain 16 steps. Each attenuator comprises two or three resistors and a changeover switch. With the switch in the ‘NO’ position, it completes a resistive divider from the preceding stage to ground, with the attenuated signal appearing at the resistor junction feeding into the next stage. With the switch in the ‘NC’ position, the divider is disconnected, and the upper resistor(s) are ‘shorted out’, so the stage has no attenuation. Calculating the required resistor values is done assuming that the source impedance is zero for the first stage, which is reasonable as it is from an op amp output. The second stage calculation is for 12dB attenuation, and the source impedance is now 25kW (due to the 25kW output impedance of the first stage). The stage output impedance also 25kW. The following stages are calculated using the 25kW input and output impedance values. The output from the attenuators is applied to another op amp buffer, IC5b. The attenuator switches are TS5A22362 dual-channel SPDT analog switches. These are interesting because not only are they very low resistance switches (0.65W typical), with low distortion (below 0.0041% at 1kHz) but also the signal can be below the supply rails for the switch. So while we run each switch IC from a 0-5V supply, the applied signal can be up to -5V without causing extra distortion. If you plan to use a different analog switch, make sure the supplies (and control voltage) for the switch are suitable. John Clarke, Silicon Chip. Original concept: Raj. K. Gorkhali, Nepal. ($75) Australia's electronics magazine An easy way to measure SMDs Here is an idea inspired by the SMD Test Tweezers project (October 2021; siliconchip.com.au/Article/15057). When using fat leads from a multimeter or similar to test small individual SMD components, they have a habit of acting like a circus flea and jumping out of sight, never to be found again. To solve this, I added a thin copper film recovered from an SMPS transformer to the teeth of a cheap set of callipers (which should be made from an insulating material) and secured the test leads to the copper. I used super glue to hold the film to the callipers. The smallest SMD component can be firmly captured and restrained from escaping. I modified a second calliper with longer leads to connect to a multimeter for holding and measuring resistors. Michael Harvey, Albury, NSW. ($60) June 2022  91