Electronics Forum / Basics / February 2008

so I am looking at the back of a package of common LEDs (yes, from
Radio Shack, I have my asbestos flame suit on :-), and it shows a
schematic for illuminating LEDs in what I perceive to be a parallel
configuration.  The schematic demonstrates 2 LEDs, with the anodes and

How would I go about building a charger for a lead acid battery.
Jaycar Electronics sells a 5 amp hour 6 volt SLA battery for use in
flashlight lanterns, but as far as I can tell they don't sell the
charger.

I'm trying to construct and understand the Relaxation Oscillator
circuit in the Art of Electronics. The circuit simply has a voltage
divider connected to the positive terminal (with equal R's), and the
negative terminal is connected to a feedback resistor to the output

I want to build I volume control for a battery powered amplifier I use
for my iPod, but I'm not sure what wattage value the pots have to be.
The amplifier outputs around 1 watt per channel.
The volume circuit I found was in a post on this newsgroup from 2001

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I am looking for a temperature probe..
The purpose, is I bought a silent enclosure for a hard drive.  So the
hard drive is sealed tight in this air tight box. The box has a little
slit for wires to come out.  And I will place the temperature probe`s

Hi, I'm a high school teacher and I've been working on a transistor
revision sheet for my students. I'd appreciate any comments on the
sheet I have made. Its at:
http://docs.google.com/View?docID=dg57p3md_27hjs34bgc&revision=_latest

I'm helping a guy with a microcontroller project.
He's going to use some BCD thumbwheels to set a time delay.  He
purchased some at a local surplus store for a buck each.  But they
were 9's complement thumbwheels, not standard decimal-coded switches.

I'm trying to put together a Tesla coil following plans for a vacuum
tube based design.
I need to find the following parts, and wondered if these could be
salvaged from anywhere...

Drinking urine?
It works by helping balance the bodies hydrogen ion ratio through feedback
when we are sick.
Our bodies are essentially capacitors and receptors(electrical storage

Is it possible to construct a simple inverter gate using 1 or 2
transistors and resistors?
I tried the circuit below but it doesn't work at all.
                            VCC

I've just finished some basic electrical training, and now would like to
start learning electronics as a hobby. I'm curious about how some of you
started and what sort of projects or tools (oscilloscopes? expensive
meter?) would be appropriate for a student.

That would monitor the battery and LED be green till the
battery went below, let's say 9-10V?, then red. The smaller the circuit
the better and of course should take as little power from
the battery as possible! Looking for a schematic?

my can controller is attached to my microcontrolled over several pins.
I allready have procedures to access the registers of the can controller.
How do i realized memory mapped IO ??
Regards

I just picked up my first scope, it's a Gould OS4100 digital
oscilloscope, I'm not quite sure if it's working correctly or not. I
would appreciate any insight for this thing.
Thanks