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Possible ghost in amplifier I just bought a Technics SU-V460 amplifier and when search­ing the net I came upon your page www. siliconchip.com.au/html/featserv. htm where I found the SU-v460 under the title “When The Ghost Comes Early”. What does that mean? Have I bought a problem amplifier? (How about the sound? Is it garbage? I had a really old Pioneer before and I think it sounded better; it had a warmer round sound. (M. J., via email). • ”When the Ghost Comes Early” transformer to the PC board or from the transformer output lead to the PC board? Also where does the arc go to on the PC board? Moving the transformer should prevent arcing to the PC board. Perhaps the PC board does have a fine unetched copper area under the transformer area. Alternatively, the DC-DC converter section may be producing a very high voltage. This should be checked out. Dimming problem with speed alarm I recently built the Speed Alarm described in the November & December 1999 issues and apart from stuffing up the location of the sensing unit and having the driveshaft kill it I am very pleased with the unit’s operation and the ease of changing set­tings. The sensitivity of the LED display at night in dim mode is irritating as street lights cause it to go from intense to dimmed too easily. Very bright sunlight also makes the unit difficult to read. Is was the headline on a TV Serv­ iceman story in our December 1991 issue and it also included a servicing story on the Technics amp. If you would like a copy we can supply the December 1992 issue for $7.70 including postage. We have not had any experience with the SU-V460 but we would expect it to be fairly run-of-the-mill. Some, but not all, older amplifiers may sound better than some newer amplifiers (we are hedging a fair bit here) because most older amplifiers had discrete output stages whereas quite a few modern amplifiers are based on monolithic designs (ie, large ICs). there anything I can do to improve this situation. Could the unit be adapted to work as a cruise control as this feature would be nice to have when driving on the highway? (M. D., Donvale, Vic). • The dimming is supposed to operate quickly so that the brightness of the display reacts to the prevailing light condi­tions, to make it easy to read. You can slow down the dimming reaction time by connecting a capacitor across the LDR. A 100µF 16VW electrolytic would be suitable but take care with the polarity. There is little that can be done to make the specified LED displays visible in direct sunlight. They need to be shaded from sunlight. Alternatively, you can use sunlight-readable common anode displays such as the HDSPH151 types from Agilent Technolo­gies. Farnell sell these under their catalog number 264-313. Phone 1300 361 005. The unit is not suited to operating a cruise control. FM transmitter for guitars I am interested in the Minimitter described in the April 2001 issue. Would this type of transmitter work well in a guitar setup? Would the signal be of good quality and hold true to the guitar? Also what type of kit would you suggest for the receiver. I plan on connecting the receiver kit direct to my amp. • The Minimitter should work well with guitars. We have de­ scribed a mono FM receiver in the November 1992 issue but we would be inclined to use a good quality AM/FM stereo tuner to drive your amplifier. Better still, since you are likely to moving around a stage, you may like to consider our Dual Diversi­ty FM Tuner described in the August & September 1994 issues. This design has two inbuilt FM tuners and constantly switch­es between the two to give the best reproduction. Notes and Errata PowerPack, May 2001: the PC board number should be 11305011. AA-cell White LED Torch, May 2001: the PC board number should be 11205011. LP Doctor, January & February 2001: the overlay diagram and parts list in the February issue describe the dual ganged 50kΩ front panel sensitivity pot as VR2. It should be VR4. Similarly, the testing procedure under adjustment (4) mentions VR2 being set at mid-position. This should refer to VR4. 4-Digit Counter, May 2001: the text on page 41 text describes the SET switch as SW1. It should be SW2. Similarly, the INC switch is referred to as SW2 SC and it should be SW1. 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 Trade Practices Act 1974 or as subsequently amended and to any governmental regulations which are applicable. June 2001  101