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94 September 2008
I live two miles south of the US
border. My TracPhone only works
reliably about 3/4 miles south of the
border. At my residence, I can
occasionally get just one bar on my
phone. I would like to improve this. Is
cell phone range limited by my transmit
power or my receive distance?
Can I rig some kind of reflector/
antenna/booster amp to improve the
range of my phone, so I don't have to
pay for international service?
#9081 G. Frank Humiston
How do manufacturers specify
parameters of passive components?
One example is a 1A diode. Is
1A the maximum current allowed, or
is the diode guaranteed to pass 1A
continuously? Another example is a
resistor. When you use a resistor as a
20 mA current limit to an LED powered
by 13.8V, isn't a 1/4W resistor pushed
over the limit?
I actually limit LED current to
anywhere between 15-18 mA. The LED
is just as bright, but lasts much longer
(lasts forever compared to our short
lifetime). I had several of these "LED
lightbulbs" burn out within a year due
to bad design by their manufacturers.
I have several Maytag Neptune
washing machine motors with the
I would like to make an adjustable
speed generator so that I could use
these motors on wood working tools. I
was thinking that a 555 series chip
would be the basis, but I don't know
how to get the three phase output.
Also, would I drive one or two phases
of the motor at the same time?
One thought was to use the 555 to
cut the power to one winding at a time
sequentially and leave power on the
other phases. I don't know how Maytag
did this. I don't want to use a
microprocessor chip if I can avoid it.
#9083 Bob McKnight
Does anyone have a circuit or info
to safely regulate high voltages from
200 volts to about 50 volts? Or how to
cascade adjustable voltage regulators
to add up their outputs to any desired
high voltage to about 200 volts?
#9084 Todd Grigsby
I need a way to find a break and/or
weak connection in a radio dog fence.
Preferably some kind of signal
injector with a radio signal strength
meter that can help pinpoint breaks or
poor splices in a wire.