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Advertising Index Altronics.................................43-46 Blackmagic Design....................... 7 Dave Thompson........................ 103 DigiKey Electronics..................OBC Emona Instruments.................. IBC Hare & Forbes............................... 9 Jaycar.................. IFC, 26-27, 36-37 Keith Rippon Kit Assembly....... 103 LD Electronics........................... 103 LEDsales................................... 103 Microchip Technology.................. 5 Mouser Electronics....................... 3 PCBWay....................................... 11 PMD Way................................... 103 SC Ideal Bridge Rectifiers........... 68 SC GPS Synchronised Clock...... 82 Silicon Chip Binders................ 103 Silicon Chip PDFs on USB......... 42 Silicon Chip Subscriptions........ 25 Silicon Chip Shop................ 69, 79 The Loudspeaker Kit.com.......... 93 Wagner Electronics..................... 10 Errata and on-sale date Simple LC Meter, May 2026: the initial batch of PCBs sold, including in kits, were inadvertently based on an old version of the board that had the USB power input pins shorted together on the bottom ground layer. All PCBs we supply have now been replaced with the correct boards without the short circuit. Also, the parts list called for M2 × 5mm machine screws, but that is too short. The correct screw length is 10mm. Our kits now include the longer screws. Next Issue: the August 2026 issue is due on sale in newsagents by Monday, July 27th. Expect postal delivery of subscription copies in Australia between July 24th and August 12th. 104 Silicon Chip March 2017 issue. This is for wiring up a single-channel SC200 to the mains power supply. Use similar wiring for the second stereo channel. Only join the grounds of the two modules at one point, ideally at a star Earth point. Are power amplifiers inverting? Firstly, thanks for the excellent magazine and projects. I have a question regarding your Studio 350, Ultra-LD and SC200 power amplifier designs. Are these non-inverting amplifiers, ie, are the output signals in phase with the corresponding input signal? I want to use them in an active threeway speaker system utilising a pair of the Studio 350s on the bass drivers and two pairs of Ultra-LD 200W amplifiers for the midrange and tweeters. I need to make sure there aren’t any phasing issues at the crossover frequencies. The speakers are Jamo R909s. The ULDs are superb amps, quiet with a neutral and detailed sound. (J. M, Auckland, NZ) ● Those are all non-inverting amplifiers. We don’t think we have ever published an inverting power amplifier, although some of our amps have been bridged types with both outputs being actively driven (so the – outputs are effectively inverting). It generally isn’t important whether a power amplifier is inverting or non-inverting, since you can almost always swap the speaker connections if you want to reverse the phase. While it’s possible to design a power amplifier to be inverting, it usually results in a more complex circuit for no real benefit. If you needed an inverting power amplifier, you could use one of our Amplifier Bridge Adaptors (May 2019; siliconchip.au/Article/11626), ignoring the non-inverted output. Air conditioner controller wanted I have a problem that I think may be common to other owners of reverse-­ cycle AC units. My nearly new Daikin unit has difficulty tracking the setpoint that I put into the remote. This is particularly the case when used with cooling. If I set it for, say, 21°C, the unit just keeps running until the room is very cold, many degrees under the set point. Australia's electronics magazine Setting the temperature higher has little effect, and the actual room temperature will fluctuate depending on the ambient conditions. I understand the difficulty for the manufacturers – the temperature sensor is located on the wall unit, instead of somewhere else in the room. I don’t understand why they don’t make a remote that communicates constantly with the wall unit to maintain a steady room temperature. I was considering cobbling something together by combining a thermostat with an IR transmitter to simply send the on/off code to the wall unit from the other side of the room and wonder if you have ever published something that would do the trick. Perhaps your Circuit Notebook entry on the Micromite-based Air Conditioner Remote Control (December 2017; siliconchip.au/Article/10914)? I lodged a service call under warranty and was called back by a company engineer who basically told me that that is just the way it is. (K. W., Newport, Vic) ● This does seem to be a design flaw in many split-system air conditioners, especially considering that IR sensors that can read the average temperature in a room are available and are not expensive (like our Thermopile-based Heater Controller from the April 2018 issue; siliconchip.au/Article/11027). We don’t have a great solution for this since there are too many different kinds of air conditioners to support. As you suggest, a remote sensor that could send commands to the unit via infrared would seem to be an ideal solution, but it would have to be tailored to the specific brand and possibly model. The December 2017 circuit you mentioned should work if you can get access to an on/off switch. Arduino libraries are available for controlling Daikin air conditioners (eg, https://github.com/danny-source/ Arduino_DY_IRDaikin). Temperature sensor interface libraries are also easy to find. We also have some Daikin air conditioners to test with, so we will consider putting together an Arduino-based remote controller with an onboard temperature sensor that can either switch the unit on and off, or adjust its settings, to provide better control of the room temperature. If this works, readers could potentially expand the code to work with different brands SC and models. siliconchip.com.au