READER-TO-READER TECHFORUM
>>> QUESTIONS
Wire Termination
What connectors seem to be the
choice of electronics hobbyists when
assembling electronics projects on
perf board? Also, is there a standard
regarding the spacing of the "perfs" on
the boards?
#2121
Don Henderson
Tewksbury, MA
Capacitors
I found hundreds of caps inside a
broken computer I’ve taken apart, but
have no idea what they are all used
for. I know that they store energy,
however, I want to hear what you can
do with them.
Is it just timing and smoothing?
I’m looking to create circuits, and am
puzzled by them.
#2122 Wesley La Ferriere
Madison, NJ
Tools
I’m just getting started in electronics and need advice on what kinds of
tools I should get to make my projects
easier.
#2123
Wesley La Ferriere
Madison, NJ
Two AC Switches, One Fan
I have two different bathroom
vents going into the same exhaust
fan. I want to sense either or both
switches to access the main relay to
run the fan (kind of like an OR gate
which I can make from logic gates for
DC).
However, my situation calls for AC
switches and fans, and I cannot think
of a way without converting to DC to
be able to switch the AC (long way
around).
Is there a simple solution using
two 110 VAC switches to turn on the
exhaust fan, and then off when both
switches are off?
#2124
78
Raj
Fairfax, VA
February 2012
Home Intercom System
I would like to put together an
intercom system for my house. I want
to be able to connect multiple
stations, perhaps up to 10 or 12. I'd
like to use twisted pair wiring, not
shielded wire (for example, existing
two pair telephone or four pair CAT
5). I would like to use a central power
supply rather than individual batteries
or power supplies. I don't need hands-free operation, so a simple push to talk
function would be fine, and I'm not
concerned about privacy, so when
one station is talking, all stations
would hear the conversation.
I've seen some two station circuits
using LM386 but I can find nothing
about creating a multi-station system.
#2125 Terry Palmer
via email
RF Security Fence
I have buried two insulated wires
about a foot apart and maybe six
inches deep around the perimeter of
my yard.
The idea is for a security fence
that will detect people/animals/cars.
The theory is one wire transmits
the RF signal, while the other is a
receiver. Any change in signal (and
some PIC processing) will flag an
intruder.
I can’t get it to work. Has anyone
tried this and/or can offer any advice?
#2126 Frederick M. Raposa
Vallejo, CA
What’s Up With 10- or 12-bit
Scopes?
Why is it such a problem for
"stand-alone" scope manufacturers to
use 10- or 12-bit A/D converters?
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
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publisher. Answers are submitted
I have seen a few PC-based 10-bit
units and a 12-bit one, as well. (They
do it.)
There is a flood of inexpensive
scopes even at the 200 MHz range
(with all kinds of bells and whistles).
No way will I even consider
upgrading my 20 MHz, eight-bit scope
until I get more vertical resolution.
Any thoughts?
#2127 Frederick M Raposa
Vallejo, CA
DC Reducer 48V to 12V
I need a simple breadboard circuit
to reduce 48 VDC to 12 VDC. I was
able to create one, but did not have
enough wattage to support my 12V
lights and radio. I know I will need a
heatsink, but any other help would be
appreciated.
#2128
Bill Fitzpatrick
Pepperell, MA
Audio Electronics
I want to construct an audio
amplifier which will have a USB input
for audio songs.
Previously, I have constructed
many audio systems, but now I want
to add USB input where I can get
songs just by pluging in a USB stick or
memory card.
#2129
Sohail Anjum
Islamabad, Pakistan
>>> ANSWERS
[#12112 - December 2011]
Pump Shut-off Needed
There is an electric pump on our
boat that moves diesel fuel from one of
four main fuel tanks to a day tank to
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