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Coming up in Silicon Chip 12V Battery Isolator This solid-state device automatically connects an auxiliary battery for charging when the vehicle alternator is running. It can handle charge currents in excess of 100A, does not get hot during operation, produces little to no EMI and has a low current drain when off. Audio Millivoltmeter This Arduino-based meter has three input ranges (200mV, 2V and 20V) plus balanced and unbalanced inputs. It provides an accurate audio signal level reading in µV/mV/V and dBV. It has better resolution than our previous designs, in a more compact package. Micromite LCD BackPack V3 This new Micromite BackPack is still cheap and easy to build, but now supports larger touchscreens, plus has onboard provision for a real-time clock, temperature, pressure and humidity sensors, an infrared receiver and even more useful functions! Rechargeable LED bicycle light This device uses a switchmode converter to drive a string of LEDs from a rechargeable lithium-ion battery pack. It has multiple light modes and automatically reduces the LED current to prevent overheating. Advertising Index Altronics...............................36-39 Ampec Technologies................... 9 Cypher Research Labs............... 6 Dave Thompson...................... 111 Digi-Key Electronics.................... 3 Emona..................................... IBC Hare & Forbes....................... OBC Jaycar............................ IFC,53-60 Keith Rippon Kit Assembly...... 111 LD Electronics......................... 111 LEACH Co Ltd........................... 25 LEDsales................................. 111 Microchip Technology................ 11 Mouser Electronics...................... 5 Ocean Controls......................... 12 Radiation and Electronics PCB Designs........................... 111 The operation of electronics in aircraft and spacecraft (and here on Earth too) can be affected by radiation. It can even cause permanent damage. This article explores the sources of radiation that can affect electronics, what problems that radiation can cause and how to prevent or overcome those effects. Rohde & Schwarz........................ 7 Speech Synthesis with Raspberry Pi and Arduino Silicon Chip Wallchart.............. 76 Use a very low-cost Raspberry Pi Zero and this small add-on board to allow any computer or microcontroller to produce synthesised speech in a variety of languages and accents, and play back music and audio recordings. If you use a Pi with WiFi, it can even play internet radio streams. Silicon Chip Shop......44,104-105 Note: these features are planned or are in preparation and should appear within the next few issues of Silicon Chip. Tronixlabs................................ 111 The July 2019 issue is due on sale in newsagents by Thursday, June 27th. Expect postal delivery of subscription copies in Australia between June 25th and July 12th. Wagner Electronics................... 10 SC Frequency Counter.............. 31 SC Vintage Radio DVD............ 108 Silicon Chip Subscriptions....... 99 The Loudspeaker Kit.com......... 65 Vintage Radio Repairs............ 111 Wiltronics Research.................... 8 Notes & Errata DSP Active Crossover/Parametric Equaliser, May 2019: in the ADC circuit diagram on pages 30 & 31 (Fig.4), two pairs of 22µF capacitors are shown between the ±9V rails and ground but only one pair actually exists. Also, one 10µF bypass capacitor is shown on the +5V rail but there are actually two, with the other located close to IC4/IC5. Finally, the two 47µF coupling capacitors after FB1/FB2 are actually polarised, with the positive ends to FB1 & FB2. Circuit Ideas Wanted Got an interesting original circuit that you have cleverly devised? We will pay good money to feature it in Circuit Notebook. We can pay you by electronic funds transfer, cheque or direct to your PayPal account. Or you can use the funds to purchase anything from the SILICON CHIP Online Store, including PCBs and components, back issues, subscriptions or whatever. Email your circuit and descriptive text to editor<at>siliconchip.com.au 112 Silicon Chip Australia’s electronics magazine siliconchip.com.au