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Next Issue The July 2015 issue of SILICON CHIP is on sale in Newsagents by Thursday 25th June. Expect postal delivery of subscription copies in Australia between June 22nd and July 3rd. been damaged. The former is available from Jaycar or Altronics. If you’re going to replace those parts you should inspect all the solder joints carefully, especially the SMD capacitors, to minimise the chance of another failure after doing the repair work. Headphone amplifier for hearing-impaired My hearing aids do a reasonable job of improving intelligibility when listening to TV or music via an A/V amplifier and speakers. However, for private listening via headphones, I was wondering if you would consider a project for a small stereo amplifier/ equaliser between the headphone sock- KEEP YOUR COPIES OF AS GOOD AS THE DAY THEY WERE BORN! ONLY 95 $ 1P4LUS p&p A superb-looking SILICON CHIP binder will keep your magazines in pristine condition. * Holds up to 14 issues * Heavy duty vinyl * Easy wire inserts ORDER NOW AT www.siliconchip.com.au/shop et and ’phones which would have an individually adjustable or programmed boost response to mirror one’s hearing loss curves, as programmed into the hearing aids? What do you think? (T. S., Tauranga, NZ). •  What do other readers think of this idea? LED strobe not bright enough I was wondering if you could assist me. I have built the LED Strobe project (SILICON CHIP, September 2008), as supplied in kit form by Altronics. However, the LED does not appear to be as bright as other 1W LED lights I use. In fact, it is considerably dimmer. I have powered the kit from a small 12V sealed lead-acid rechargeable battery (12V 7.0Ah) to make it portable and re-chargeable. I need to use the unit in day conditions (not direct sunlight but still a fair amount of light where I need to work) and at present I am limited to pre-dawn and post sunset operation. Is there any way to modify it so that I can increase the LED brightness? (C. K., via email). •  The 1W LED is being driven with the correct current, so you may need to use the 3W white version of the Luxeon or Cree LED to get more light. Q1 would need to be replaced with an IRF540 Mosfet with the gate, drain and source in the base, collector and emitter connections for Q1 respectively. The 220Ω resistors from RB4 and RB5 should be changed to 22Ω. Then the 3W LED can be driven with higher current. This requires that the 39Ω 5W resistor be replaced with two paralleled 22Ω 10W resistors. Additionally, the 1N4004 diode (D1) needs to be a SC 1N5404 (3A) diode. Advertising Index Altronics.........................loose insert Emona Instruments........................ 3 Hammond Manufacturing............... 8 Hare & Forbes.......................... OBC High Profile Communications....... 95 Icom Australia................................ 5 Jaycar .............................. IFC,45-52 KCS Trade Pty Ltd..................... 7,24 Keith Rippon ................................ 95 LD Electronics.............................. 95 LEDsales...................................... 95 Master Instruments...................... 11 Microchip Technology................... 13 Mikroelektronika......................... IBC National Instruments...................... 9 Ocean Controls.............................. 6 Questronix.................................... 95 Radio, TV & Hobbies DVD............ 88 Sesame Electronics..................... 95 Silicon Chip Binders................ 44,96 Silicon Chip Online Shop........ 34-35 Silicon Chip Subscriptions........... 70 Silvertone Electronics.................. 27 Tronixlabs..................................... 95 Worldwide Elect. Components..... 95 X-ON Electronic Services............ 95 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. 96  Silicon Chip siliconchip.com.au