Electronics Forum / Basics / April 2004

i've just started to read about imaginary or reactive power my text
book doesn't seem to cover to much information on this subject.
any additional information on this subject would be greatly
appreciated

I am contemplating building an idea I have had for some time, and in the
process learn more than just basic electronics. Without going into great
detail at this phase, I would like to implement a serial bus in order to
communicate with multiple receivers each with it's own binary ...

I need to know if the following circuit will/can oscillate,
http://www.geocities.com/myelectronicsrevision/fmtxastable.jpg
thanks!

I'm trying to repair a NAD 3140 amplifier which has had a couple of
components burn out.  The resistor that burned was identified by
looking at the mirror side of the amp. but the cap that was burned is
still a mystery.  The markings are 104 EAE.  There are many of these

I am looking for a Beeper Circuit (using a Piezo Buzzer/Sounder) which when
triggered should produce two beeps (pip-pip) every 5 seconds. Will prefer a
circuit using dual-timer 556 or CMOS/ TTL logic gates. Any help
appreciated - Tks

There is a really good graphical simulation of the inner worrkings of
a 555 timer chip at http://www.williamson-labs.com/ under 555 on the
left frame.
However, I am trying to follow what is happening and think that I

I just recieved a 465B Tektronix oscilloscope.
It was an ebay purchase and came without manuals. I have ordered a
book and videotape package that teaches one how to use an
oscilloscope. I also have a manual for a similar unit that was

What about a configuration such as this one here
http://www.uoguelph.ca/~antoon/circ/fmt2.htm
We know that the base of the transistor settles on 0.7V.
Does this mean that the microphone will only have 0.7V,

Can someone point me to a circuit that i can use to turn on a 12V DC relay at a
preset voltage input, i want to monitor the variable DC tacho drive signal in
my car and turn on the relay to operate a solenoid. Something that can be set
with a potentiometer would be ideal.. ive ...

I have been trying to figure out what AC phases are under the hood.
All I know is that they allow you to make high voltages like 220,208,
240, etc, and they you need more than 1 hot wire. I know to run a 2**v
clothes dryer, you need to have the black wire as a + and take a red

I have an opamp (OPA348 to be exact) in a non inverting configuration.
Take a standard noninverting configuration (two resistors in series
from output to ground, resitor junction connected to inverting input),
but instead of connecting the resistor network to ground, connect it

If I connect an old silver dollar into a circuit, will I be
"exchanging electrons, many of which haven't left it since 1823"?
Hmm, if I usually kept it in a plastic mount, then I guess yes.
Hmmm, of course, OK, never mind.

http://www.maxim-ic.com/appnotes.cfm/appnote_number/142
Please see the above link, a PC printer port data logger system, built
around with MAX132 (±18-Bit ADC with Serial Interface).
I am very keen to have such a data logger for my project work,

There seems to always be a great deal on LEDs by EBay sellers.  Has anybody in
ABSE or SEB had any experience with any LED's purchased in this manner?
I found on auction the other day (too lazy to look up now) that had 100 white
LED's for $4.99.. Too good to be true?

I am looking for good and simple schematic of sensitive metal-detector on
large width (approx. 1,5-2 meter). Please, help!
Thanks.