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limit of 64 stations in total that it can store. We are unsure of the reason for this limitation as the designer of that project left Silicon Chip many years ago. We assume it is due to the limited amount of flash memory or RAM available. It’s possible that could be changed, but we no longer have a prototype to test new firmware, nor are we confident that compiling the source code with a current compiler will necessarily produce working code without being able to test it. Our much more recent Touchscreen DAB+/FM/AM Tuner design (January-March 2019; siliconchip.au/ Series/330) does not suffer from this problem. It must have an upper bound on the number of stations it can tune, Advertising Index Altronics.................................43-46 Dave Thompson........................ 103 Digi-Key Electronics...................... 3 element14................................... 11 Emona Instruments.................. IBC Hare & Forbes............................. 13 Jaycar.......................... IFC, 5, 7, 21, ..............................24-25, 77, 79, 99 Keith Rippon Kit Assembly....... 103 LD Electronics........................... 103 LEDsales................................... 103 Microchip Technology.................. 9 Mouser Electronics..................OBC Ocean Controls............................. 8 SC Pico BackPack.................... 101 but nobody has run into it yet. Also, the source code is available (it’s written in BASIC), so it could easily be fixed if such a limitation existed. While the parts for that project are somewhat hard to come by, we do have a handful of Si4689 ICs on hand for anyone who wishes to build one, and the PCB, Explore 100 kit and other associated parts are still available – see siliconchip.au/Shop/?article=11369 Consider, though, that this newer project requires some fairly small SMDs to be soldered. But we think that is a better situation than the old tuner, which needed a module that wasn’t available to purchase (it only came as part of the now-discontinued Jaycar kit). Replacement pot for Class-A amp My 20W Class-A amplifier (MaySeptember 2007; siliconchip.com.au/ Series/58) is in need of a new volume pot as it has gone all scratchy. It is an Alpha dual-gang 20kW log motorised pot, previously sold by Altronics as Cat R2000 but no longer available. Do you know of a suitable replacement? Is it possible to retrofit one from another brand? (N. M., Sunbury, Vic) ● We suggest you try spraying some contact cleaner into the wiper assemblies first as that might resolve your scratchiness with much less expense and hassle than replacing the pot (eg, try Jaycar Cat NA1012). If you do need to replace it, the pot value is not so critical (eg, you could use a 10kW or even 5kW dual-gang log pot). The main concern is it fitting on the existing preamp PCB. Bourns Pro Audio PRM162-K420K103A1 is a 10kW dual gang logarithmic pot with dimensions very similar to the Alpha unit Altronics sold. The PCB SC SMD Test Tweezers.............. 63 Silicon Chip Shop.................70-71 Silicon Chip Subscriptions........ 23 Silvertone...................................... 6 The Loudspeaker Kit.com.......... 10 Tronixlabs.................................. 103 Wagner Electronics..................... 73 104  Silicon Chip Errata and Next Issue Silicon Chip Binders................ 103 probably would need some slight modifications to make it fit (due to slightly different motor mounting posts) but we think it would not be too hard to retrofit. Unfortunately, it is somewhat hard to find anyone with this in stock. Verical list 142 in stock at the time of writing and we have purchased from them before, so we think that is a reasonable option (siliconchip.au/ link/abdh). Master Electronics also say they have 147 in stock but we have no experience with them – see siliconchip.au/ link/abdi Stereo Compressor kit wanted Is the Stereo Compressor kit still available? It used to be sold by Jaycar, but they no longer supply it; I hope you can help. (A. B., Christchurch, NZ) ● We designed two different Stereo Compressors that were made as Jaycar kits, one in June 2000 (siliconchip.au/ Article/4328; Jaycar Cat KC5291) and one in January 2012 (siliconchip.au/ Article/809; Jaycar Cat KC5507). Jaycar makes their kits based on our articles; we do not make them for Jaycar. It does look like both Jaycar kits are no longer available. You might be able to get a kit for the January 2012 design from Altronics (Cat K5526). It is still listed on their website; it looks like they are very low on stock, but they have kits in a few stores. Perhaps if you contact them, they can get one back to their warehouse and deliver it to you. Failing that, we can supply PCBs and panels for the January 2012 design, see siliconchip.au/Shop/?article=809 You would need to get the rest of the parts yourself. It looks like they are still available; the critical part is the SA571 IC (in DIP), and they are for sale on eBay. SC Spectral Sound MIDI Synthesiser, June 2022: the orientation of diode D2 in Fig.9 is incorrect. Install it with the cathode stripe facing to the right, as shown on the PCB silkscreen. Digital FX (Effects) Pedal, April & May 2021: Fig.2 in the April issue shows incorrect connections for op amp IC3b. Its pins 5 & 6 are swapped. Pin 6 (−) should be at the top, connected to the 4.7μF capacitors, while pin 5 (+) should be at the bottom, connected to Vcc ÷ 2. The PCB has the right connections. Next Issue: the September 2022 issue is due on sale in newsagents by Monday, August 29th. Expect postal delivery of subscription copies in Australia between August 29th and September 16th. Australia's electronics magazine siliconchip.com.au