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Notes & Errata
Appliance Earth Leakage Tester,
May 2015: the parts list includes
one 100nF MKT capacitor but two
are required.
Ultra-LD Mk.4 Power Amplifier
Module, July-September 2015: the
parts list on page 38 of the August
2015 issue gave an incorrect part
number for the 4.7V zener diodes. It
Ask SILICON CHIP
. . . continued from page 95
switch-boxes, built with the best quality audio quality components. Do you
know where a switch-box anything like
this is available? Alternatively, where
I can get suitable parts to build one (I
haven’t been able to find a good 4-way
switches, for phono use in particular)?
Ideally I’d like a 4-outlet switch-box
but anything with at least two outlets
would be acceptable. The only option
I’ve been able to find so far is to use a
different headphone amplifier (made
by Musical Fidelity) which has dual
phono outlets (non-switchable) but
could do the job if I’m willing to spend
some money (either $350 or $900) to
downgrade the quality of my headphone amplification by using it.
If I can’t buy something like this or
get it built anywhere, where is an electronics shop that could custom design
and build it for me? Could consider
having 10-100 of them made and reselling them though headphone shops
if need be, if I can’t get just two. I hope
you can point me in a good direction.
(G. C., via email).
• We published a Two-Way Stereo
Headphone Adaptor in the April 2008
Advertising Index
should be BZX84B4V7-7-FDICT-ND.
The ferrite bead type isn’t critical but
we suggest Digi-Key 240-2548-1-ND.
Altronics.........................loose insert
9-Channel IR Remote Control Receiver (September 2015): a bug in
the receiver code could cause the
last used function to be repeated in
the presence of interference. The revised code 1510815B.hex fixes this.
Hammond Manufacturing............. 13
Control Devices Group................. 15
Emona Instruments........................ 7
Hare & Forbes............................. 2-3
Icom Australia................................ 8
Jaycar .............................. IFC,45-52
KCS Trade Pty Ltd...................... IBC
Keith Rippon ................................ 95
issue which can switch between two
sets of headphones. However, the fact
that there are resistors and pots in the
signal path, with no buffering, means
that it would not meet the high standards for distortion set by the Studio
Series Headphone Amplifier (SILICON CHIP, November 2005) and more
particularly, by the much higher performance headphone amplifier described in the September & October
2011 issues.
With your existing set-up, all you
really need are three 12V DPDT relays
wired up to a rotary switch (or similar)
such that the coils are energised to connect the input socket to one of the four
output sockets. It can be totally passive
and as long as the wiring is kept short
and the whole thing is housed in an
earthed metal case, it will have negligible effect on sound quality. After
all, we pass hundreds of watts from a
power amplifier through a 10A DPDT
relay in our speaker protector module
with virtually no measurable effect on
sound quality.
At the much lower voltage/current/
power levels for driving headphones,
and given the higher load impedances,
as long as good quality relays are used
SC
it should be fine.
LD Electronics.............................. 95
LEDsales...................................... 95
Master Instruments.................. OBC
Microchip Technology................... 11
Ocean Controls............................ 61
Radio & Hobbies DVD.................. 44
Rohde & Schwarz.......................... 5
Sesame Electronics..................... 95
Silicon Chip Binders..................... 87
Silicon Chip Online Shop........ 88-89
Silicon Chip Subscriptions........... 90
Silvertone Electronics.................. 12
Splat Controls................................. 9
Tendzone...................................... 10
Tronixlabs................................ 13,95
Next Issue
The December 2015 issue of SILICON CHIP is due on sale in newsagents by Thursday 26th November.
Expect postal delivery of subscription copies in Australia between
November 25th and December 7th.
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
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