Electronics Forum / Basics / July 2004

Hello Group.
I need advice on isolation transformers!
Are the yellow 240V-110V building site transformers isolated?
I have purchased a 110V variac and wish to supply it with isolated

I am trying to get a small gas powered engine running, (Rockwell) and I need
some help electrically. I have the unit running on the bench, with a simple
on/off switch, and a 12 volt marine battery.
I can get it started absolutely ok, but what I'm wondering, is it possible

Someone asked me to attempt to fix an audio problem with a unique
video game system that has internal speakers that do not work at all.
But the system has connections for external speakers. And only one of
the two external speakers will work depending on what game PCB is

  Me and a few people have taken to retrofitting in HID (High
Intensity Discharge) i.e. Xenon headlights into our non-hid equipped
cars. We use projectors from OEM cars, BMW, Mercedes, Audi etc...
which serve to make the headlights have no glare... i.e. we're not the

I have never studied RF communications. With that said I have a
question about how antennas work, and I am talking about simple
antennas (simple straight wires) like on a car.
How can an AC current exist in a wire that is connected to some

i look for Bosting power supply the negative voltage with 79xx
Please cess me for explication Jean.dupont@cgocable.ca
Thank you

 I need to add separate volume controls to an existing 9 office speaker
system.
So as it stands, the 9 speakers have impedance-matching transformers on them
and they are wired in parallel to the 70v tap on the amp.

Watching BBCA this morning there was a story on voting in Afghanistan.
Folks were running mock elections to train for the upcoming elections.
A sight guard made of cardboard was being used at one of the tables.
It said on the box "GOLD FREE COMPUTER". I can't imagine there is much

I am kinda new here... was wondering where to get the components from.
I am located in ottawa Canada.. any suggestions.. any cheap and reliable
websites?
PLease reply here :)

I am in the middle of installing a whole garden irrigation system.
I want to build a controller for this, but need some kind of moisture sensor
It will be interfaced to a PIC with a simple high/low input
Any ideas on where I can either buy some, or plans on building them?

   At what voltage is a Pic's input pin considered high or on, i.e.
do you have to be higher than say 1 volt. I've looked all over and I
am sure the answers out there but I can't seem to cut through the
mountains of information.

I have a number of blue LEDs, that work when connected to a resistor
and a 9V battery (don't know much else about them!)
How would I go about making a wall socket to I could plug in a group
of LEDs?

All who are interested in Basci Stamp microcontrollers,
I bought one of the Homework board kits advertised in Nuts & Volts. I
am pleased with the product. At the $80.00 sale price it's a good way
to learn about the Basic Stamps. The only drawbacks so far are the

has anyone used this seriously as a design tool? it comes with the linux
distro i have, and i've used it for drawing schematics, but not sure if
it's worth taking the time to learn how to use the netlist/spice parts of
the program.

If I'm going to create a LED flashlight, and the majority of my LEDs
have a forward voltage of 3.5volts - which battery setup should I
choose?
1.  ONE single 9volt battery connected to all my LEDS (in parallel)