Electronics Forum / Basics / December 2004

I would like to check out a temperature sensor for my central heating
cylinder. 2 cables coming from the sensor.
What voltage do I need?
What should change with the rising temperature?

I want to build a microwave gun to boil the butts of my enemies.
What do I need?

I've been studying electronics on my own for a little while now, and
there's one basic concept I can't seem to get my head around. I
apologize in advance for the really basic question, but I just can't
find the answer and it's keeping me up at night.

Hey guys, I picked up two rotating solenoids at a surplus store
recently and I haven't the slightest clue on what voltage to use.  I
googled the Serial Numbers but these solenoids seem to not be very
common.  Should I just try random voltages , do I run the risk of

Has anyone else seen these panels out there?  They are ridiculasly priced at
over $400 for a 2x2 ft. square panel made up of 4 cubes.  The cubes change
colors and I am interested in understanding what kind of light they are
using.  Any thoughts by the pros?

First of all, I am completlely new to electronics and have just begun
trying to learn, so I apoligize if this is a super simple question.
I have a power source that is 5 volts. Is this 5 volts per circuit? or
total?

Hello,I made a simple astable 555 timer circuit the same as the one on
the 555 web site,but im having trouble working out the values of the
two resistors and the capacitor so it will turn on for 3 minuts and off
for 5 minuts.Could someone please point me in the right direction as i

I'm reading Tom Frederickson's "Intuitive IC Op Amps" - in particular pg 15
concerning the op-amp schematic, and am not sure how the second stage of the
op amp works.  This stage that takes the single ended current and converts
it a voltage before it's off to the output stage.

For an example:
   Is a 1/4 watt 270 Ohm resistor the same as a 270 Ohm SMD resistor? I've
never used the SMD kind.
Thanks for the help.

A while ago i posted a question about what I can do with that dish i found.
Something useful i though others might like
http://www.wwc.edu/~frohro/Airport/Primestar/Primestar.html

I have several AC/DC Adaptors.
I often find that the voltage listed on the Adaptor is not the voltage that
it gives out. eg it might say 4.5 but when I put the volt meter on it shows
as 5.8 or something not under load.

i would like to build a variable electromagnet that is directly
connected to a computer controlled (220v AC) dimming unit. i suppose
that dimming the electric current will lower the magnetic field and
thus its attractive force? the (somewhat creative) goal is to

I am a violin maker, and I need a circuit for a signal generator, to test
the resonant frequency of my fronts and backs.
Spec...
Range 20hz to 10Khz

I need a circuit that can perform the following
if (x < -1)
x = 0
else if (x < 1)

I have a working idea for making some LED Modules that I want to use
in my SUV for Car Shows.  I want to use a 12 volt positive and ground
setup in a 3 by 3 LED configuration.  I'm trying to figure out if I
should put the lights on a board or just wire them together.  If I put