I have CD and DVD players
which, when playing certain discs,
will stutter, skip, cut in and out, and
sometimes abort the playing altogether. It only does it on some discs, and
at the same place on these discs.
However, these same discs will work
on other players just fine. On at
least one player, the problem got
progressively worse, and had trouble
with discs it played without errors in
the past. Is there a way to repair this?
Cleaning the lens and disc sometimes
helps, but not always. I am playing
only commercially made CDs and
DVDs, not home burned ones.
#1101 Michael Kiley
Tunable Sine Wave Generator
I am working on a project to
provide 100 inexpensive, disposable
electronic devices for a church.
Each device requires a cheap, low-distortion, parts-stingy sine wave
generator, easily tunable using only
one pot from 1 kHz to 1 MHz, preferably using one common and cheap IC
like an op-amp or a few transistors. To
be compact, the parts count should
be under about a dozen. I have plenty
of XR8038 and XR2206 function
generator ICs, but they are far too
costly for this project. My experiments
have produced only square waves or
triangular waves, but meet all my
other criteria. What is the best sine
Can anyone help me find
the datasheet for the following
component: RA2892 from Raytheon?
Also what is an equivalent (cross
reference) that I can use?
#1103 Mohamed Fathi
I have a problem with my speakers
humming on my desktop PC. I think
this may be wall wart related but not
Is there a way to fix this problem or
do I need to buy a new set of speakers?
#1104 John Sparozich
Automotive Speed Sensor
I recently replaced the trans in my
Ford van. Somewhere between 00
and 02 model years, Ford changed the
speed sensor output to the PCM, but I
have an analog gear driven sensor.
The newer sensor is digital (variable
reluctance). I need to change the
signal back to analog so the
speedometer, ABS, and cruise will
work. Is there a device to do it, or is it
I've had electronic engineering
schooling back in the 80's and have
tinkered a little since then. I've never
had a computer until now and would
like to know some free or reasonable
circuit design/test software download
sites to tinker with.
[#9091 - September 2009]
I have a door access control
system that uses 110 VAC normally but
has a 7 Ah battery for backup power.
This only offers a very short time
All questions AND answers are submitted
by Nuts &Volts readers and are intended
to promote the exchange of ideas and
provide assistance for solving technical
problems. Questions are subject
to editing and will be published on a
space available basis if deemed suitable
by the publisher. Answers are submitted
period of battery power should the AC
fail. Its built-in power supply/charger is
rated at 1A. My question is, what are
the ramifications of substituting a
much larger battery for the 7 Ah one?
Aside from the possibility that once
depleted, a higher amp hour battery
would take longer to recharge and
possibly not even recharge fully, are
there any other detrimental possibilities
to the system or the battery?
#1 There are several issues with a
1. You have correctly stated that
a longer recharge time will occur if
charging current is not increased.
Most chargers I have seen are based
upon the LM317 as a current
limiter/voltage regulator. You can
find charger circuits in the National
Semiconductor LM317 datasheet.
Many of them will limit current and
turn off accurately at a certain voltage.
The battery will recharge fully, but will
simply take longer to recharge (roughly
with Ah capacity, twice as large,
charge time multiplied by two, etc).
You can easily measure the charge
current with a DMM, but both
batteries should be in the discharged
state. You should not see any
2. The larger battery will provide
considerably higher short circuit
currents to the connected circuits and
needs to be properly fused.
3. It is common for larger
batteries to be installed separate
from other equipment due to their
particular requirements for venting and
corrosion they can cause. You were
most likely looking at a non-vented,
gel-type sealed lead-acid battery which
by readers and NO GUARANTEES
WHATSOEVER are made by the publisher.
The implementation of any answer printed
in this column may require varying degrees
of technical experience and should only be
attempted by qualified individuals.
Always use common sense and good