Electronics Forum / Design / April 2005

I am working on a home surveillance system and I need to do a DC
voltage reduction. I have a supply that is 12v DC @ 80 ma and need to
reduce the voltage to a max of 9v @ 80 & 120 ma (variable load).
As I understand I can do this with a resistor? If so, what size and

I have a possibly very interesting instrument application that requires the
application of a very large ac voltage, about 3 kV p-p anywhere between 20
and 50 GHz--it doesn't much matter where.
The actual power dissipated in the instrument is quite small, so I don't want

How easy would it be to build a sweep generator using  555 timer chips or
even a 556?
The frequency coverage has to be 20khz to 80khz.
I need three, one has to go from 20khz to 80Khz, one has to go from 20khz to

Dear Friends,
   We are on to designing a communication board based on the NEC V850
microcontroller that will have a USB port for communicating with a PC.
The board requires a supply voltage of 5V and draws at the most 300 ma

 I have been wandering if it ever possible to make an Optical Mouse to
become a BarCode Scanner.
When i think abt it, an optical mouse works pretty much like a barcode
scanner, whereby a sensor in the device will pick up the reflected

I've been using Saber for years and would like to become more
"PSPICE/SPICE" knowledgeable.  Can anyone recommend a good book?
I'd like to come up to speed on Cadence Capture, PSPICE, and detailed
editing of SPICE models.   Apparently, the models I'm finding are

Hi everyone, again,
sorry to bother this group again -- it's just the most suitable I've
found for my questions. :-)
Anyway, I'm a tad curious about the two different chemicals I use to

Andy writes:
How many people here have heard of BOB WIDLAR and have any
personal experiences to tell ?
Hint:  LM709

Anyone know of links or ideas for self build (hobbyist electronics)
projects for home automation whether this be the x10 type system or
other wired or wireless ideas?
I am in particular interested in computer control so I guess all the

We've got a very old Dell computer, of the '486 vintage.  The power supply
resembles that seen used with countless ATX form-factor motherboards.  My
son can use the +5 and +/- 12 volts for his science project.
There is a 20-contact connector that plugs into the mobo.  I presume that ...

A few days ago, I started a thread to ask if it would be feasible to
create a line powered audio switch connecting one stereo output to
either of two inputs.
After a nice discussion with many people, I came up with a schematic

I have a friend that has an old TV set and wants to see videos using a
CD video player. Since the TV doesn't have a video input, the signal
must be converted toRF.
Can't I use the modulator on the VCR and tune the TV to channel 3/4 ?

Any good online tutorials on orcad layout for 10.3i version?
thanks

I have a bunch of x y flatbed recorders and I want a simple rising
volatge to simulate passing time on the x axes. I can work from a
diagram and know some basics. HP made this in a small package.... HP
17108A.... anybody have one?

A recent post highlighted the possibility that the new pope has an opinion
about music.
How many guesses will it take you to name the Pope alive at the time of this
particular song? Bid me a number of words from the start of the song.