Fullscreen HTML5Med Res (??MB)HTML4

Notes & Errata Circuit Notebook, September 2015: in the item titled “Benchtop Ignitor For Oxy-acetylene Welding”, the IGBT’s part number in the circuit is incorrect. It should be ISL9V5036P3. Note that this part is available from our Online Shop. Automatic Reverse Loop Controller For DCC Model Railways, October 2012: a 10μF 16V capacitor should be added to the parts list. Ask SILICON CHIP . . . continued from page 103 need to do something different? I imagined it would be similar to any double switch circuit. (G. L., via email). •  It’s hard to say exactly what the problem is without knowing how the existing controller works. For example, if one switches the +12V supply to the motor for speed control while the other switches the 0V connection, the motor would run at full speed regardless of the setting. That may be what you have experienced. While not an ideal solution, you may be able to get it to work by connecting each controller to the motor via a separate pair of series diodes (at either end of the motor), to isolate the controllers from each other. Questions on antenna designs Thanks for the useful articles and “how-tos” with regards to the two antennas in the October and November 2015 issues of SILICON CHIP. However, something is lacking (from my per- spective) and that is how you came to the dimensions that you used? Can you supply the calculations that you used? Any format is fine, including an excel spreadsheet or plain text. The reason for asking is that I am interested in boosting reception for other bands. Also, what is the best way to boost reception in the AM band? (C. D., via email). •  Both designs were based on 5element Yagis in the ARRL Antenna Handbook. This book is readily available on-line. The best way to boost AM reception is to use a loop antenna. We have described several, the most recent being in October 2007 and March 2005. Preamplifier for Currawong amplifier I am interested in building the Currawong amplifier but it sports only one input and an optional remote volume control board. For me, one input is a bit of a nuisance, so as an alternative I purchased and am currently building your Studio Series Preamplifier, described in 2005 and 2006. My question is, can the Currawong be driven by your Studio Series Preamplifier without damage? (S. D., via email). •  If you operate both the Studio Series Preamplifier and the Currawong at the maximum gain settings, you will certainly overload the amplifier and possibly damage your speakers but would you really do that because the loudness and distortion would be extreme? The best approach to avoiding overload is simply to set the Currawong’s volume control so that no matter high you advance the volume control on the preamplifier, the loudness will not be SC excessive. Advertising Index Altronics.................................. 80-83 Av-Comm Pty Ltd........................... 5 Emona Instruments........................ 4 Hare & Forbes.......................... OBC High Profile Communications..... 103 Icom Australia................................ 7 Jaycar .............................. IFC,49-56 Keith Rippon .............................. 103 Keysight Technologies.................... 3 LD Electronics............................ 103 LEDsales.................................... 103 Master Instruments.................... 103 Microchip Technology................. IBC Ocean Controls............................ 12 QualiEco....................................... 59 Radio & Hobbies DVD.................. 90 Sesame Electronics................... 103 Silicon Chip Binders................ 91,95 Silicon Chip Online Shop............. 23 Silicon Chip Subscriptions........... 13 Silvertone Electronics.................... 9 Tendzone...................................... 11 Tronixlabs................................ 8,103 Next Issue The January 2016 issue of SILICON CHIP is due on sale in newsagents by Monday 28th December. Expect postal delivery of subscription copies in Australia between December 28th and January 8th. WARNING! SILICON CHIP magazine regularly describes projects which employ a mains power supply or produce high voltage. All such projects should be considered dangerous or even lethal if not used safely. Readers are warned that high voltage wiring should be carried out according to the instructions in the articles. When working on these projects use extreme care to ensure that you do not accidentally come into contact with mains AC voltages or high voltage DC. If you are not confident about working with projects employing mains voltages or other high voltages, you are advised not to attempt work on them. Silicon Chip Publications Pty Ltd disclaims any liability for damages should anyone be killed or injured while working on a project or circuit described in any issue of SILICON CHIP magazine. Devices or circuits described in SILICON CHIP may be covered by patents. SILICON CHIP disclaims any liability for the infringement of such patents by the manufacturing or selling of any such equipment. SILICON CHIP also disclaims any liability for projects which are used in such a way as to infringe relevant government regulations and by-laws. Advertisers are warned that they are responsible for the content of all advertisements and that they must conform to the Competition & Consumer Act 2010 or as subsequently amended and to any governmental regulations which are applicable. 104  Silicon Chip siliconchip.com.au