Electronics Forum / Basics / April 2005

I have a cordless floor sweeper that's missing the wall wart power
supply it came with.  Inside the sweeper there is a 7.2 volt nicad pack
with just a power resistor to limit current to the battery when
charging (very primitive).  The resistor is something like an ohm, and

My machine has a receiver from Shima Digital.  It receives at 308 MGz.  Will
a transmitter at 310 MHz trigger it to go on and off?

Hi, Let me start by saying that I know very little about
electronics,but I would like to know how to hook up 8 white leds to 120
volt ac. Is as simple as going to Radio Shack and buying a transformer?
If so what size transformer will I need to get? Thank You,Randy

I have electronics hobby and just start learning how oscillator works,
like the loop gain must be >= 1 and the phase between the input and
output should be 0 degree. The problem is, when I see the actual (even
simple) oscillation circuit, I am at a loss how it exactly works.

Can anyone help?
I have a 1/4 hp ac motor that I am looking to make into a drum sander
ex.   http://www.pixelpuddle.com/sanders/
so the motor that I have has eight wires. The diagram is as shows

Hi - I want to mount a portable DVD player to the roof of the minivan so if
anyone has experience dealing with a later model roof liner please lend me
your thoughts -
I'm thinking something temporary that could be screwed into female

I need to shorten the end of my solder iron so i have more control of
direction and make it more like a pen.....can i cut it down so my
fingers are nearer the tip without causing a problem.....thought it
might cause a problem with heat distribution and overheat..........i

Can anyone figure out the input impedance of the circuit attached here:
http://physicsforums.com/showthread.php?t=73070 ?
Does anyone know a THOROUGH definition of input impedance? output
impedance?

It really depends on what type of alarm clock you use(AC/DC) and what you want to drive with the relay(AC/DC/Load/etc...)
If you just want to set up a relay to go off at a certain time of day, I would use a cheap wrist watch, connect the piezo beeper wires to an opto coupler which ...

Can anyone suggest the best way to shape a single wire carring a
current so that it's magnetic field cancels itself out?  Completely if
possible.  I'm trying to optimize the idea for light weight and varying
current values.  All I can think of would be to bunch the wire into a

Wondering if I need to buy a NiMH charger for NiMH batteries or a
normal AA charger will work with the NiMH batteries. Can anyone tell me
if this is possible?
Thanks in advance!

i have i slight problem, and its got me stumpe
i need to produce a block diagram for a simple mircoprocessor system
showing how a 74LS138 logic device could be used as part of th
address decoding, if 4 * 1 Kbyte memory devices are to be used with

Hi - I'm working on a project to make an 8x8 LED array. The idea is that
the anodes in each row are tied together, and the cathodes in each column
are attached together, giving me 16 pins which I can control 64 LEDs with.
But now the only problem is making sure they get the right ...

I would like to build a device to connect a CCTV Camera to a TV using an old
VCR Modulator, does anyone one have a svhematic of this - I remember seeing
a circuit a few years back but can't find one now.
Cheers.

I made a half-dipole antenna for my home stereo from wire scraps I had.  It
works fine, but unfortunately, my two favorite radio stations are
geographically 90 degrees apart (East, and South).  With the dipole being a
directional antenna, that, of course, means sacrificing one ...