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Altronics.................................77-80 Dave Thompson........................ 111 Digi-Key Electronics...................... 3 element14..................................... 7 Emona Instruments.................. IBC Hare & Forbes............................... 9 Jaycar.............................. IFC,53-60 Keith Rippon Kit Assembly....... 111 Lazer Security........................... 111 LD Electronics........................... 111 LEDsales................................... 111 Microchip Technology.................. 5 Mouser Electronics..................OBC Ocean Controls........................... 11 Silicon Chip Shop............ 106-107 The Loudspeaker Kit.com.......... 10 Tronixlabs.................................. 111 Wagner Electronics..................... 97 way to modify it to run by default using 15.5 as the target ratio. Would this require changing the wideband sensor? (P. F., Willoughby, NSW) ● The sensor actually measures the lambda value, and the air/fuel ratio is calculated from that. That means the same sensor and controller will work fine regardless of whether you are using petrol or LPG. It will show a lambda of 1.0 if the mixture is stoichiometric, irrespective of the actual air:fuel ratio of the fuel being burned. Oxygen sensors measure whether the exhaust has excess oxygen (lean) or no oxygen and unburnt fuel (rich) or completely burnt fuel with no oxygen leftover (stoichiometric). The sensor does not actually measure the air/ fuel ratio directly. If you want to display the air/fuel ratio rather than the lambda value, the unit needs to know the stoichiometric ratio for the fuel you are currently using. The problem is that the fuel type could change. Since you usually use LPG, you could just set that to 15.5:1 and realise that the readings displayed when running on petrol will be 5.5% too high. But the engine won’t care since 112 Silicon Chip Running appliances from higher voltages I would like to request assistance regarding a Panasonic hair dryer made in Japan. It is labelled as 100V 1200W. Can I run this from 110V AC? I can plug it into a 110V outlet, but in the long run, the motor will fail. Could I use a Triac-based circuit? Thank you very much. (D. H., Taipei, Taiwan) ● One method is to use a transformer to reduce the mains voltage, as in our Mains Moderator project (March 2011; siliconchip.com.au/Article/937). The secondary windings are wired in series with the primary but out-of-phase. The result is that the secondary voltage is subtracted from the original mains voltage before being applied to the load. That circuit was designed for the Australian mains voltage, nominally 230V AC. But the same applies to your 110V supply if you use a suitably-rated transformer with a 10V or 12V tapping to reduce the mains voltage by that amount. Note that the 1200W hair dryer draws up to 12A (assuming most of the load is the resistive heater element), so the transformer would need to have a secondary current rating of at least 12A. That’s a large transformer. An alternative is to use two strings of around 10 diodes, one set for either mains polarity, to drop the 10V. But the diodes would need to be rated for 12A and preferably 20A, meaning they would need to be substantial devices. Either circuit would need to be installed in a suitable Earthed enclosure with the correct input and output plugs and sockets. The diodes would need heatsinking to the case and isolated electrically. You could use a phase controller Errata and Next Issue Advertising Index it’s using the lambda value. Note that the air/fuel ratio also varies depending on the fuel grade. So it’s better just to show the lambda value as it will always be correct. with a Triac. We don’t have a circuit that would work at 110V AC, as our designs are for 230V AC and wouldn’t be powered sufficiently. Also, most of our designs are rated for 10A rather than the 12A required for the hair dryer. Also note that the Triac would reduce the RMS voltage, but the peak of the 110V waveform would still be applied to the motor. If you can get a 110V AC rated Triac-based dimmer that can handle 12A or more, you could use that. But we think you might find it easier (and possibly cheaper) to purchase a 110V-rated hair dryer. Is Playmaster 136 up to modern standards? I would like to know if the Playmaster 136 preamp could be used in an Ultra Low Distortion Amplifier, primarily because I’m running out of funds and would like to still be able to use my record player. (M. G. M., Trott Park, SA) ● The Playmaster 136 is from the 1970s era and has a poor signal-tonoise ratio and high distortion compared to anything we have published recently. You could use it, but it wouldn’t be doing the amplifier justice. Given your limited budget, consider building the Ultra Low Noise Remote Controlled Stereo Preamp (March & April 2019; siliconchip.au/Series/333) without the input switcher and using a standard 16mm potentiometer in place of the motorised pot. You can then omit the microcontroller, 5V regulator and all components in that section. You could still use our PCB. That would give you a preamp with excellent performance that you could probably build for around $40 (depending on where you get the parts, which exact parts you use etc). It doesn’t have a built-in RIAA preamp but you can get an external RIAA premap for your turntable from Jaycar for $21.95 (Cat AC1649). SC 500W Power Amplifier pt2, May 2022: inductor L1 is wound using 13.5 turns of 1.25mm diameter wire, not 30.5 turns of 1mm diameter as stated in two places on p64 & p65. Around 900mm of wire will be consumed. Model Railway Semaphore Signal, April 2022: trimpots VR1 & VR2 are 1kW, not 10kW as shown in Fig.8 on p56. Next Issue: the July 2022 issue is due on sale in newsagents by Monday, June 27th. Expect postal delivery of subscription copies in Australia between June 27th and July 11th. Australia's electronics magazine siliconchip.com.au