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Coming up in Silicon Chip AD584-based precision voltage references Jim Rowe looks at three low-cost but very precise voltage references, all based on the Analog Devices AD584 IC. They can provide very stable 2.5V, 5V, 7.5V or 10V reference outputs, which can be trimmed to within a fraction of a millivolt of the ideal reading. Australian International Airshow 2019 Dr David Maddison attended the biennial Avalon airshow and will describe all the latest technology (military and civilian) presented at this world-class aviation showcase. Bathymetry through the ages Dr David Maddison describes how the use of knotted ropes and timber poles to measure water depth gave way to sonar. But modern sonar is about more than just water depth measurement. It can be used to map the seafloor, for discovering and imaging wrecks and other submerged objects. High-current linear bench supply This power supply has low ripple and noise due to the use of linear regulation. But it can still deliver plenty of current (more than 5A) with an output of up to 50V. Using 3.5-inch touchscreens with Arduino & Micromite We’ve used 2.8-inch touchscreens extensively over the last few years but larger displays with a significantly higher resolution are now available with reasonable price tags. They use the same SPI interface and so can easily be hooked up to and controlled by an Arduino or Micromite board. Advertising Index Altronics...............................66-69 Ampec Technologies................... 9 Cypher Research Labs............. 10 Dave Thompson........................ 95 Digi-Key Electronics.................... 3 Emona..................................... IBC Hare & Forbes....................... OBC Jaycar............................ IFC,45-52 Keith Rippon Kit Assembly........ 95 LD Electronics........................... 95 LEACH Co Ltd........................... 79 LEDsales................................... 95 METCASE Enclosures................ 6 Microchip Technology........... 11,75 Mouser Electronics...................... 5 Ocean Controls......................... 13 Philips.......................................... 8 Rayming PCB & Assembly.......... 4 UHF repeater Based on reader requests, this device extends the range for devices such as our 2015 Driveway Monitor which use UHF transmissions to send data from a remote unit to a base station. It can both extend the usable range and also solves line-of-sight problems caused by hills or obstacles that are in the way of the signal. Rohde & Schwarz........................ 7 Note: these features are planned or are in preparation and should appear within the next few issues of Silicon Chip. Tronixlabs.................................. 95 The May 2019 issue is due on sale in newsagents by Thursday, April 25th. Expect postal delivery of subscription copies in Australia between April 23rd and May 10th. SC Vintage Radio DVD.............. 93 Silicon Chip Shop...............88-89 The Loudspeaker Kit.com......... 55 Vintage Radio Repairs.............. 95 Wagner Electronics................... 12 Notes & Errata DAB+/FM/AM radio, February 2019: in the parts list on page 85, we wrongly described the BC817 transistors as PNP and BC807 as NPN. BC817s are NPN and BC807s are PNP. The type numbers and part designators given are otherwise correct. Also, note that the 5.5 turn side of T1 is terminated on the CON6 side, as described in the text; this is not clear from Fig.2. Four-channel sound system using a single woofer, Circuit Notebook, February 2019: the circuit diagram does not show the part type for ICs3-9. The author recommends LM833 although NE5532 should also be suitable. Low Voltage DC Motor and Pump Controller, October & December 2018: for PWM frequencies above 1kHz, a 30V+ schottky diode must be connected across the fan/pump, cathode to positive, with a current rating at least half the load’s maximum. Solder it across the unit’s outputs or the fan/pump terminals. This prevents the Mosfets from overheating when they absorb the back-EMF pulses. We also suggest that you solder 10µF 25V X5R capacitors on top of the 100nF bypass capacitors for IC2 and IC3 and add a 2200µF 25V low-ESR electrolytic between the +12VF and 0V (fan power input) terminals on the board. Note that the loads may run briefly when power is first applied; disconnect all loads before making a connection to CON2 (ICSP). USB Port Protector, May 2018: TVS2 has a metal tab under its body which is not mentioned in the article, and depending on how you fit it, it could become shorted out. Make sure that this tab only makes contact with one of the two pads before soldering it in place. 96 Silicon Chip Australia’s electronics magazine siliconchip.com.au