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lose time with a regular quartz movement. SemTest not generating a high enough voltage I built the SemTest Semiconductor Tester (February, March & May 2012; siliconchip.au/Series/26) but it does not reach the maximum test voltage of 600V. I followed the instruction in the magazine to build it, but it only reaches 350V. Thank you. (Anon., Philippines) ● We suspect there is nothing wrong with the flyback transformer. It will Advertising Index Altronics.................................23-26 Beware! The Loop....................... 12 Blackmagic Design....................... 9 Dave Thompson........................ 111 DigiKey Electronics....................... 3 Electronex................................... 13 Emona Instruments.................. IBC Hare & Forbes............................ 6-7 Jaycar............................. IFC, 55-58 Keith Rippon Kit Assembly....... 111 Lazer Security........................... 111 LD Electronics........................... 111 LEDsales................................... 111 Microchip Technology.............OBC Mouser Electronics....................... 4 OurPCB Australia.......................... 5 PCBWay....................................... 11 PMD Way................................... 111 SC Pi Pico W BackPack.............. 79 Silicon Chip Binders.................. 54 Silicon Chip Bridge Rectifiers... 87 Silicon Chip PDFs on USB......... 86 Silicon Chip Shop.... 100, 106-107 Silicon Chip Subscriptions........ 27 The Loudspeaker Kit.com.......... 10 Used Gear - Dieter Dauner........ 111 Used Gear - Jim Rowe.............. 111 Wagner Electronics..................... 99 Next Issue: the April 2025 issue is due on sale in newsagents by Thursday, March 27th. Expect postal delivery of subscription copies in Australia between March 26th and April 11th. 112 Silicon Chip only develop 600V if relay 2a is operating, and that is when its coil is being driven via the pin 12 output of IC6. There could be a dry solder joint at one of the connections or an incorrect 680W resistor value at the normally-­ open contact of relay 2a. Check the PCB for correct placement of components and correct resistor values. Change in Jaycar LCD shield supplier I have run into a problem with the “Arduino RFID Keypad” project on the Jaycar website (www.jaycar.com. au/rfid-keypad). The current version of the LCD shield that Jaycar is selling (XC4630) is no longer compatible with the code for that project. Since the Jaycar website is undergoing some changes, the full details of this project are at https://github.com/ Jaycar-Electronics/RFID-Keypad-­ Relay Over time, the LCD shield suppliers to Jaycar have changed and consequently the code has three different configuration defines in the XC4630d.c file to cater for the different LCD shields. Unfortunately, none of these define options bring the current version of the LCD shield to life. A white screen is always the result. After doing some research and installing the MCUFRIEND_kbv-­ master library, I found that running the “diagnose_TFT_support” sketch with the included “MCUFRIEND_kbv. cpp” file having the “#define SUPPORT_8347D” line brought the LCD shield to life. The tft.readID() function returns a value of 0x7575, indicating that the LCD shield is using a HX8347G chipset. While I am comfortable turning on or off existing, pre-coded #defines, I don’t have the knowledge required to change the code to bring the LCD shield to life, hence my request for help. (T. G., Smiths Lake, NSW) ● We came across this same problem while designing our Symbol Keyboard project that was published in the May 2024 issue (siliconchip.au/ Article/16250). You have followed the same path as us, using the MCUFRIEND library to identify the LCD controller chip. For that project, we updated the XC4630d.c file to add support for the Australia's electronics magazine HX8347 controller. You can download the updated software files from: siliconchip.au/Shop/6/378 Use our newer version of the XC4630d.c file and make sure that XC4630_v4 is uncommented. Since you have already identified the controller, we see no reason why this should not work. We also recommend powering off the Arduino board after changing these configurations and uploading the sketch. This will ensure that it forgets any incorrect commands that were previously sent to the LCD controller when the Arduino board tries to configure it. That shouldn’t be necessary in theory, since a reset signal is sent, but we have needed to power cycle the board on occasion. Component values for Cartridge Preamp I have a query regarding the Magnetic Cartridge Preamp project (August 2006; siliconchip.au/Article/2740). I am wondering about Table 4 on page 51, especially the values for R1. R1 for the Westrex curve is listed as an 18nF capacitor. I am guessing this should be a 220kW resistor. Related to that, should the 220kW value for R1 for ffrr78 response curve be some other value? If 220kW gives a flat response, it will not suit a treble turnover frequency of 6.36kHz. Is it supposed to be an 18nF capacitor? Finally, what value of R1 will give me a treble turnover freq of 5.5kHz? (D. M., Hughesdale, Vic) ● R1 = 18nF for the Westrex curve is correct. This sets a stepped response at approximately 200Hz with the 33nF capacitor for C1 in parallel with 18nF (R1) that is then in series with resistor R2 (18kW). Note also that a capacitor is also used in the R1 position for the NARTB curve in Table 2. For the ffrr78 curve, the 220kW resistance seems correct. For a 5.5kHz turnover, change C2 to 1.8nF. We have created LTspice simulation files for the Westrex and ffrr curves that you can download from siliconchip. au/Shop/6/1826 You can change the values and run the frequency response for these to see the response to changes. If you don’t have LTspice, it is a free download from siliconchip.au/ link/ac2p SC siliconchip.com.au