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Contents Vol.34, No.7 July 2021 SILICON CHIP www.siliconchip.com.au Features & Reviews 12 The 2020 mission to Mars On July 30th 2020, the Perseverance rover and Ingenuity helicopter were launched into space. They arrived at Mars on February 18th 2021 to search for evidence of past life and find signs of habitable areas – by Dr David Maddison 36 How USB Power Delivery (USB-PD) works With the introduction of the Type-C connector came a new power delivery specification called USB-PD. It allows 0.5-100W of power (20V at 5A maximum) to be delivered. This article describes how it works – by Andrew Levido 42 El Cheapo Modules: USB-PD chargers A quick look at three different USB-PD power sources, which includes the Comsol COWCC30WH, XY-PDS100 and Belkin F7U060AU – by Jim Rowe NASA’s latest (and current) robotic visitors to Mars are the nuclearpowered Perseverance rover and its companion, the Ingenuity helicopter – Page 12 73 Review: Tecsun PL-990 radio receiver The Tecsun PL-990 is a high-performance AM, FM, shortwave (SW) and longwave (LW) portable radio all-in-one. The only downside is that it might be Tecsun’s last high-end portable – by Ross Tester Constructional Projects 26 20A DC Motor Speed Controller This small speed controller can drive motors rated up to 24V DC and 20A, with adjustable soft-start time, variable PWM frequency and minimum duty cycle adjustments, along with many more features – by John Clarke 46 Model Railway Level Crossing Moving barriers, flashing lights and a bell sound recorded from a real level crossing make this a realistic part of a model railway layout – by Les Kerr Our 20A DC Motor Speed Controller uses pulse width modulation (PWM) to drive motors rated from nearly 0 to 24V at 0-100% duty cycle – Page 26 64 Silicon Labs-based FM/AM/SW Digital Radio Single-chip technologies, like the Si4730 and Si4732 from Silicon Labs, make it much easier to build a capable digital radio which receives FM, AM and SW signals with just a handful of components – by Charles Kosina 76 Advanced GPS Computer – Part 2 The second, and final article, has the construction details of the Advanced GPS Computer along with how to use it and, for those that are interested, how the software works – by Tim Blythman Your Favourite Columns USB 3.2 is the first standard to officially allow power sources and sinks to negotiate the supplied voltage and current. This powerful feature is named USB Power Delivery – Page 36 61 Circuit Notebook (1) Coded door buzzer (2) Adding shuffle to a low-cost MP3 player module (3) DIY pulse oximeter 91 Serviceman’s Log I’ve repaired planes before, but never ‘tanks’ – by Dave Thompson 98 Vintage Jukebox The Rowe AMI JAL-200 jukebox – by Jim Greig Everything Else 2 Editorial Viewpoint 4 Mailbag – Your Feedback 104 Silicon Chip Online Shop siliconchip.com.au 106 Product Showcase 107 Ask Silicon Chip 111 Market Centre 112 Noteselectronics and Errata Australia’s magazine 112 Advertising Index This new FM/AM/SW Radio is smaller and uses fewer components than the previous BK1198-based model. It can use the Si4730 IC for AM & FM reception; or the Si4732 which also includes SW reception – Page 64 July 2021  1 Cover image: https://mars.nasa.gov/ resources/25757/curiositys-selfie-at-mont-mercou/