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Advertising Index Altronics.................................23-26 Blackmagic Design....................... 7 Dave Thompson........................ 103 DigiKey Electronics....................... 3 Emona Instruments.................. IBC Hare & Forbes............................. 11 Jaycar............................. IFC, 51-54 Keith Rippon Kit Assembly....... 103 Lazer Security........................... 103 LD Electronics........................... 103 LEDsales................................... 103 Melbourne Society of Model & Experimental Engineers............. 37 Microchip Technology.............OBC Mouser Electronics....................... 4 PCBWay......................................... 9 PMD Way................................... 103 Silicon Chip ESR Tweezers....... 61 Silicon Chip PDFs on USB......... 77 Silicon Chip Pico Gamer......... 101 Silicon Chip Shop.................98-99 The Loudspeaker Kit.com.......... 97 Wagner Electronics....................... 8 Notes and Errata WiFi DDS Function Generator, May & June 2024: errors on the PCB cause Button A to start channel B and Button B to have no effect, while LED T/Trig Out is shorted to ground. The two tracks currently going to pins 22 and 23 (GP17 and GND) of MOD1 should be cut and re-routed to pins 21 & 22 (GP16 and GP17), respectively. Also, both tracks currently going to pin 33 (AGND) need to be re-routed to pin 32 (GP27). Finally, in the parts list, diode D2 should be listed as a 1N5819, not 1N5189 (the diode supplied in the kit is correct). Next Issue: the September 2024 issue is due on sale in newsagents by Thursday, August 29th. Expect postal delivery of subscription copies in Australia between August 26th and September 13th. 104 Silicon Chip & Hobbies) but I admit this is one of the technically most complex I have done even though the construction was straightforward. (E. G., St Kilda, Vic) ● We are not sure how this happened but the revised circuit diagram is wrong. According to the data sheet, pin 15 of the ACS718 should be connected to GND. Vcc is pin 10; there is no FILTER pin on this part. So the PCB connections are correct. The ACS718 is not involved in voltage measurements anyway, only current measurements. We have corrected the circuit in the online edition. The mains voltage is monitored via transformer T1, op amp IC3a and ADC IC2. The output from T1 should be approximately 12V AC. The junction of the 22kW/2.2kW divider should be just above 1V AC, and pin 3 of IC3a should measure a similar AC voltage but with a 2.5V DC bias. If measuring these with mains power applied, please be very careful to keep away from all the other components and mains wiring and use a multimeter with insulated probes and a suitable voltage rating. Alternative for FR607 fast recovery diode I’m hoping you can suggest a replacement for FR607 6A 1000V fast recovery diode used in Li’l Pulser Mk.2 (July 2013; siliconchip.au/Series/178). I did some research but couldn’t find one with similar specs. Jaycar sells a pack of 10 FR607s but I only need one. (P. C., Croydon, Vic) ● You could use the MBR20100CT (Jaycar ZR1039, available separately rather than in a pack of 10). It is a different package (TO220 instead of the DO-201 axial leaded FR607). You could wire it up using tinned copper wire with the two outside pins joined as the anode and the centre pin or tab as the cathode. Ensure the device is mounted so it can’t short to other components. Covering in heatshrink tubing or securing it with neutral-cure silicone would achieve that. Alternative to 10-turn potentiometers Is there any way to make a single-turn potentiometer act like a 10-turn pot? Also, Jaycar has discontinued the Australia's electronics magazine MCP1703T-5002E/CB regulator you used in the Versatimer/Switch (June 2011; siliconchip.au/Article/1038). Is it possible to bypass the regulator and use a 7805 or 78L05? I understand the current draw will increase. Keep up the good work with the magazine. (R. M., Melville, WA) ● 6:1 reduction drives are available but it is almost certainly cheaper and easier to just use a 10-turn pot. See www.nationalrf.com/reduction.htm Yes you could use a different 5V regulator for the Versatimer/Switch as long as you take care connecting it correctly to the PCB for the input, GND and output connections. Yes, the low standby current feature will be lost if using one of those regulators. Different regulators may require extra capacitance at the input and or output. Check the data sheet for the regulator you use. Using Touch Lamp Dimmer with LED bulbs I built the Touch Lamp Dimmer from the June 1989 issue (siliconchip.au/ Article/7459) for both my bedroom and lounge. When suitable LED lamps became available, I was able to continue using the Dimmer in on/off only mode by retaining two 28W halogen bulbs in each room. Replacing the halogen bulbs is becoming a bit tedious, so I wanted to use a fixed capacitive or resistive load instead. I searched the internet, but it appears no one has published instructions on calculating the required load. The 5.5W LED lamps draw 22.4mA, while the 28W halogen lamps draw 123.8mA each. There are two halogens in each of the 12 lamps in the lounge and the 7 in the bedroom. Many thanks for your help. I have been collecting and reading your magazine since the beginning. ● It is not terribly practical to use resistors since the value required to draw the same current as one halogen bulb is 1.8kW, resulting in a dissipation of 32W. So, a 50W-rated resistor would be required, mounted on a large heatsink. You might consider instead replacing the dimmer with the Versatile Trailing Edge Dimmer with Touch Plate & IR (February & March 2019; siliconchip.au/Series/332), as it is compatible with LED lamps. SC siliconchip.com.au