Electronics Forum / Basics / June 2007

Hello, I'm a newbie and I'd like to learn a little about electric
motors.
I've had a run-through of electric motors and I understand the basics
(how they work, that they are an inductive load, etc), but I've got a

Is it possible to have an AC electric current that's 60 Hz, 5 volts,
0.01 amperes, and only 1-electron-thick?
If 1-electron-thick too thin to be impossible, then what is the
minimum thickness of electric current that's physically-possible?

A DC-DC converter I'd like to use requires an input cap with a 10A
ripple current rating (at the coverter's rated output). I'm assuming
it's a 100KHz ripple rating, the data sheet doesn't say.
I can easily find 4A or so rated caps at the capacity/voltage/ESR I'm

I am trying to debug the first stage of a pH input circuit.  The first stage
is just a voltage follower made from a TL084
The pH probe centre electrode is connected directly to the non-inverting
input of one opamp of a TL084 (this connection does not touch the PCB, it's

I have a DC source (lets say 50v) connected to a capacitor with a
switch in between. everytime the switch turns off and on again the
capacitor voltage gets hit with 50v and adding it everytime. 50 then
100, then 150 atc.. how is it possible? what is the physics behind

Hi, I'm doing some more opamp calculations just to get used to opamp
golden rules some more. I decided to do an ideal analysis on an
inverting, single-supply opamp: http://i14.tinypic.com/5xebi4w.jpg
After applying some golden rules, I got the following equations:

   I have a car that is not located near any 120VAC power, so I
cannot use a normal trickle charger to maintain my car's battery at
full charge (the car sits for long periods).  But can I use another
(fully charged) lead acid car battery, or perhaps even one of those

I have a module that takes output signal from a standard R/C receiver
for servos to control 2  DC motors (Tamiya King Tiger tank system)  .
Now I also have a Brainstem microcontroller that has servos control
output. My question is  can I plug the Brainstem's servos output to

I was looking at this circuit:
http://www.epanorama.net/circuits/parallel_output.html#mainspower
and while I see what the MOC3041 is for, what are the 4A, 400V triac
(and resistors, and capacitor) there for?

I have a circuit that runs off a 5VDC regulator.
I need to drive 2 relays, and the ones I have are 6Vdc, but ofcause they
switch fine at lower voltage.
The problem is, to switch the relay I have a transistor, and then a

    If I have a resonant L/C series circuit, how do I maximize the
Q?  Do I:  1. Make the capacitor much larger in comparison to the
inductor (IE: 1000pF cap vs. a 1nH inductor); or 2.  Make the inductor
much higher in value than the capacitor (IE: 1000nH inductor vs. a 1pF

I'm sure that someone here can help. If not, could someone please point me
to the correct group?
I wanted to make the onomatograph, however, I had a few simple questions.
1. can it be hooked up to a computer for the sound output?

I built a simple preamp from this schematic -
http://www.electronicsteacher.com/circuits-and-diagrams/audio-preamp-circuits/pr
eamp.gif
For the most part it works great - it makes guitar pickups and
microphones sound much louder.

I was told on another forum, that the way to switch "large" currents is
a MOSFET since a regular transistor cant, atleast not from a mcu output.
Now I have a few of these IRF530 MOSFETs, and are trying to get them
working.

Hey all,
Been googling for ages but couldn't find something that seems like it
would do what I need. I'm looking for a design that would generate a
single pulse when triggered but then nothing until reset even though