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Advertising Index A To Z Electronix............................ 9 ADM Instruments........................... 5 Altronics....................... Loose Insert Embedded Logic Solutions.......... 45 Emona Instruments...................... 27 Apex Tool Group............................. 3 Grantronics................................. 103 Hare & Forbes.......................... OBC High Profile Communications..... 103 Instant PCBs.............................. 103 Ask SILICON CHIP . . . continued from p102 displays have been sold as FND500s by Jaycar and other companies for quite few years so no-one has questioned this situation. The simple fix is to buy the displays from Jaycar or Altronics but we realise that might rankle a bit since you cannot use the FND500s you have on hand in this project. Red displays for frequency meter I am very interested in building the new 2.5GHz 12-Digit Frequency Counter in your December 2012 & January 2013 issues. Can you please tell me what modifications would be needed to change the three 7FB5641AB quad 7-segment blue displays to 7FR5641AS quad 7-segment red displays from Futurlec? (P. O., via email). • Erk! Red! You would prefer to use boring old red rather than the scintillating blue LED displays we used? OK, you can use the 7FR5641AS quad 7-segment red displays but as they are a little more efficient than the blue displays (at least in terms of visible brightness), you may wish to increase the value of the segment current-limiting resistors from 47Ω to 68Ω. This will reduce the display current and will probably still give you a sufficiently bright display. VHF aircraft receiver input confusion I have just finished building the VHF Aircraft Receiver from page 55 of the Circuit Notebook section in the December 2008 issue. In the first paragraph of the item, it states that 104  Silicon Chip Jaycar .............................. IFC,49-56 DOWNLOAD OUR CATALOG at www.iinet.net.au/~worcom WORLDWIDE ELECTRONIC COMPONENTS PO Box 631, Hillarys, WA 6923 Ph: (08) 9307 7305 Fax: (08) 9307 7309 Email: worcom<at>iinet.net.au Keith Rippon .............................. 103 KitStop.......................................... 11 LED Sales.................................. 103 Low Energy Developments........ 103 Microchip Technology..................... 7 Mikroelektronika......................... IBC Notes & Errata Ocean Controls............................ 23 DAB+/FM Tuner (SILICON CHIP, October to December 2010): The left and right audio channel inputs are swapped over on the PCB. This can most easily be corrected by crossing over the 100Ω resistors from from pins 1 & 7 of IC3. It is not necessary to cut or alter tracks on the PCB. Radio, TV & Hobbies DVD............ 10 Quest Electronics....................... 103 RF Modules........................... 15,104 RMS Parts.................................... 19 Satcam......................................... 11 Sesame Electronics................... 103 Silicon Chip Binders.............. 42,103 Silicon Chip Order Form............... 93 Silicon Chip Partshop................... 92 the antenna is coupled via a 10nF capacitor to the base of transistor Q1. However, the circuit diagram has the antenna connected to the emitter of Q1 via a 10nF capacitor. I have checked the errata in later editions and haven’t seen any corrections on this. Have there been notes or adjustments in SILICON CHIP about this receiver that I have missed? (K. M., via email). • Since the base of Q1 is effectively grounded by the 10nF capacitor, the input must be to the emitter, as indicated on the circuit. Grounded base amplifiers are common for RF applications. Smaller inductor for iPod charger I have a question regarding the circuit used in the article entitled “Build a Charger For Your iPod or MP3 Player” from February 2006. Silicon Chip Subscriptions........... 39 Soundlabs Group......................... 85 Tekmark Australia......................... 10 Tenrod Pty Ltd.............................. 47 Trio Test & Measurement.............. 21 Wiltronics........................................ 6 Worldwide Elect. Components... 104 I understand this article was written a while ago but I was wondering if there was an alternative to the inductor used in this project. I was hoping to use a smaller inductor to keep the project a bit smaller overall. (T. S., via email). • If you want the full charging current from the February 2006 charger, then the inductor needs to be 220µH and with the core size specified. A smaller inductor will not reduce the charger size much overall with the PC board, sockets, capacitors and other compoSC nents also taking up space. siliconchip.com.au