This is only a preview of the November 2012 issue of Silicon Chip. You can view 22 of the 96 pages in the full issue, including the advertisments. For full access, purchase the issue for $10.00 or subscribe for access to the latest issues. Items relevant to "High-Power Class-D Audio Amplifier, Pt.1":
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Advertising Index
ADM Instrument Engineering....... 37
Altronics.........................loose insert
Amateur Scientist CD................... 79
Circuit Labs Ltd.............................. 5
Cleverscope................................. 57
EAV Technology........................... 76
Embedded Logic Solutions............ 8
Emona Instruments...................... 55
Futurlec.......................................... 9
Grantronics................................... 95
Hare & Forbes............................. 2-3
Ask SILICON CHIP
. . . continued from p94
what values would you suggest for
my situation?
Finally, I’d like to include some
over-voltage protection just using a
zener diode. How is the value of resistor chosen? It usually seems to be a
low value like 10Ω. (B. W., via email).
• The input capacitor for the LM317
is not critical and can be a larger
electrolytic capacitor than the recommended 100nF and 1µF values. The
higher value would minimise the
effect of lead inductance for a long
connecting lead.
Typically a 10µF electrolytic capacitor would be suitable. This should be
rated at 35V for the nominal 24V battery (which could reach close to 30V
when charged). For added decoupling,
connect a 100nF MKT capacitor in
parallel with the 10µF electrolytic
capacitor.
A protection zener diode across the
input could be used and should be a
30V type so that it clips transients and
is not conducting with normal supply
voltage. A 10Ω series resistor would be
suitable but would need to be rated for
the current drawn from the regulator.
A 20W resistor would be needed
for 1A. This could comprise two series 4.7Ω 10W resistors or paralleled
22Ω 10W resistors. Alternatively, for
100mA drawn from the regulator, use
a larger value such as 100Ω 5W.
SLA batteries cannot
be rejuvenated
I purchased the Battery Zapper/
Rejuvenator kit (SILICON CHIP, October
2009) with the understanding that it
96 Silicon Chip
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PO Box 631, Hillarys, WA 6923
Ph: (08) 9307 7305 Fax: (08) 9307 7309
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High Profile Communications....... 95
IMP Printed Circuits..................... 12
Instant PCBs................................ 95
Jaycar .............................. IFC,45-52
Keith Rippon................................. 95
Kitstop.......................................... 93
LED Sales.................................... 95
would bring uncharged sealed lead
acid (SLA) batteries back to life but on
reading the instructions it says it only
work for car batteries.
I may have to return this kit because
of this and would like some urgent
help with the SLA battery issue. I’m
aware of the need for a battery charger
to power the circuit and just to twist
the plot, can this be a solar panel
instead (I have a 20W unit for experiments)? (R. S., via email).
• A solar panel could be used – good
idea! But sealed lead acid batteries
can’t be rejuvenated. If they have been
discharged below 11V, that generally
SC
means death.
Notes & Errata
PIC/AVR Programming Adaptor
Board (May-June 2012): since this
circuit was designed, Microchip
have released a number of new
PICs, many of which can be programmed using this board. This
includes the PIC16F150x series
(four chips). These can be programmed in mode B, not mode C
as is implied by Fig.5 on page 78
of the June 2012 issue.
For other new PICs, check the
data sheet and compare the programming pin location and supply
voltage requirements to that of
other micros listed in Fig.5.
Low Energy Developments.......... 95
Matrix Multimedia......................... 90
Microchip Technology..................... 7
Mikroelektronika........................... 29
Mouser Electronics................... OBC
NPA Pty Ltd.................................. 70
Oatley Electronics...................... IBC
Ocean Controls............................ 91
Quest Electronics......................... 95
Radio, TV & Hobbies DVD............ 78
RF Modules.................................. 96
Roland DG Australia.................... 37
Satcam......................................... 35
Sesame Electronics..................... 95
Silicon Chip Binders..................... 77
Silicon Chip Bookshop................. 89
Silicon Chip Order Form............... 83
Silicon Chip Partshop................... 82
Silicon Chip Subscriptions........... 65
Siomar Battery Engineering......... 95
Splat Controls............................... 95
Tekmark Australia........................... 9
Tenrod Pty Ltd.............................. 73
Trio Smartcal.................................. 6
Truscotts Electronic World............ 95
Verbatim Australia........................ 13
Wiltronics................................. 10,11
Worldwide Elect. Components..... 96
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