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Advertising Index Altronics.................................35-42 Blackmagic Design................... 5, 9 Dave Thompson........................ 103 DigiKey Electronics..................OBC Emona Instruments.................. IBC Hare & Forbes........................10-11 Jaycar............................. IFC, 22-25 Keith Rippon Kit Assembly....... 103 LD Electronics........................... 103 LEDsales................................... 103 Microchip Technology.................. 7 Mouser Electronics....................... 3 PCBWay....................................... 57 PE Back Issues............................. 6 PMD Way................................... 103 SC RPi Pico W BackPack........... 43 Silicon Chip Back Issues........... 53 Silicon Chip Binders................ 103 Silicon Chip DCC Kits................ 65 Silicon Chip Explore-40........... 103 Silicon Chip Kits........................ 83 Silicon Chip PDFs on USB......... 82 Silicon Chip Shop.................90-91 Silicon Chip Battery Checker.... 89 The Loudspeaker Kit.com............ 8 Wagner Electronics..................... 87 GPS Nixie Clock date wraparound I built the 6-Digit Retro Nixie Clock (February & March 2015; siliconchip. au/Series/282) soon after it came out, and it has performed faultlessly until yesterday, the 14th of June, 2026. When we woke up, it was showing UTC time, not local (as happens occasionally here), but when it finally showed local time, it was displaying one hour ahead, ie, summer time. This seemed strange until I checked the date the clock displayed, which was 29/10/06, nearly 20 years ago. I immediately thought of the GPS date rollover problem, but a quick check showed that was in 2019 and the next one isn’t until 2038. To be certain it wasn’t a glitch of some sort, I switched the unit off for several hours. When switched back on, the problem was still there. So the clock believes that today is 30/10/2006, not 16/6/2026. Apart from some really weird fault with the GPS receiver, the only other thing that springs to mind is a software bug. Are there any other possibilities? I am using an EM-408 GPS module for timekeeping. (K. O., Westbury, Tas) ● Looking through our source code, all dates are handled in BCD format, so we don’t see how there can be a wraparound or overflow until the year 2100 at the earliest. We can’t 100% rule it out, but it seems very unlikely, especially since the day and month have also changed in your case. The 29th of October 2006 is exactly 1024 weeks before the 14th of June 2026. That points to the GPS receiver reporting a date one GPS epoch too early. Errata and on-sale date for the next issue iClap intelligent multi-clap switch, Circuit Notebook, June 2026: it’s better to connect the relay contacts between the mains outlet’s Active terminal and the lamp, in series with S1. Regardless, S1 must always be switched off (and ideally the circuit breaker too) before changing the lamp because RLY1 could be energised at any time. You can’t rely on RLY1 to disconnect Active from the lamp socket for safety even if RLY1 is placed in the Active circuit. Ducted Heat Transfer Controller, September 2025: in the fourth paragraph on p68, the article mentions the Jaycar HB6116 & HB6114 vented enclosures, stating that the latter is smaller than the former; it should be the opposite. Solar-Powered Lighting System, May & June 2010: the 2.2kΩ resistor shown above IC1 in the PCB overlay diagram (Fig.6) should be 22kΩ. Next Issue: the December 2026 issue is due on sale in newsagents by Monday, November 23rd. Expect postal delivery of subscription copies in Australia between November 20th and December 9th. 104 Silicon Chip Australia's electronics magazine So we suspect the GPS module is at fault. You could connect it to a USB/ serial interface and look at the date string in the RMC messages. We suspect you will find that it’s giving out the wrong date. The EM-408 is quite an old design, released in 2007, so it was likely developed in 2006. That would explain why it has wrapped around 1024 weeks later and gone back to 2006. If that’s the case, there are two possible solutions: 1. Replace the GPS module with one that gives the correct date. 2. Make a custom version of the firmware that compensates by adjusting the date/time from the module. This will be a little involved since it will need to adjust the year, month and day to add 1024 weeks. It would probably be necessary to convert the date from the GPS module into days since January 1st, 2006, or similar, then add 1024 × 7 and convert it back to a date. The code we have shown on the previous page may be helpful. Simple audio preamp wanted Can you advise me if you have ever published a design for a simple (preferably mono) preamplifier on a relatively small PCB that can run from a single DC voltage rail? I restore valve radios at a serious hobby level, doing many for other people, and I often add a small preamp so the radios will produce adequate output when fed with an audio signal from (say) an MP3 player, which produces an audio output level is significantly lower than the level from the radio’s detector. This means that the volume control of the radio has to be turned up really high when being fed with such a signal. Until recently, I had been using the Champ preamp. While I am well aware of its design deficiencies, it worked fine. However, I have just become aware that Jaycar is no longer stocking this preamp, so I am looking for a suitable alternative. (P. W., Pukekohe, NZ) ● The 2013 Champion preamp was designed to replace the ancient Champ and Prechamp designs. Jaycar has a complete kit (Cat KC5519), while Altronics has a preamp-only kit available (Cat K6044). We can also supply a PCB or a kit (siliconchip.au/ SC Shop/?article=1301). siliconchip.com.au