Electronics Forum / Design / August 2005

Hi - I need to find some fairly large inductors. They need to be able
to handle around 5A (10A would be better) and have a inductance of
about 5mH (20mH would be better). Does such a thing even exist? Would
it be just terribly huge/expensive? I couldn't find such a beast in the

For stepper motors, PWM is the way to go if I don't want to make a
heater/driver combo.
But what is the optimum frequency for PWM, and what would be the ideal
'scope curves from a current sink MOSFET output when hooked up to the motor?

I need to digitize an array of signals (24) with minimum 8-bit
resolution, with <  2ms conversion time.  Signals are single-ended 0 to
5V.  I am trying to keep costs low, therefore I am trying to avoid
multiple A/Ds and/or complex multiplexing situations.

Anyone know of any (simple?)circuit that will do a unity gain variable degree
phase shift between 0-180 degrees? Frequency range is 0.1 to 100Hz.

hi,everybody. I have some questions about hight precesion constant
current source.My goal is 1uA whose error is blow 0.01%. In my circuit
I used a op-amp,p-mosfet and 5V voltage reference. But the result is so
bad,the error is almost 1%. Could somebody give me some hints? Thanks

I am a 14 year old trying to make a small tesla coil for fun. I would
be pleased with sparks at least 6 inches long. I have already made a
homemade capacitor, 10kv 40 nf, which I plan on adding to. I am
wondering if a glass cylindrical jar I have, 10 inches tall 2.5 inches

I have a PVC tube half an inch wide, 18 1/2 inches long that wound with
copper wire before reasearching it. I want to know if I could make a
small tesla coil with it with out seeting the frequency impossibly
high. I calculated it to have about 1628 coils of wire on it. Once I

"CNET reports that researchers from the University of Arizona and other
universities have concluded that the Arctic will likely see ice-free summers
within a century due to the increasing rate of global warming.  The melting
will raise ocean levels worldwide, flooding coastal ...

A few days ago i posted a subject about tesla coils. One person was
talking about a ring oscillator that work at the resonant frequency of
my coil, no matter what it is. here's what he wrote:
Maybe you can be really crude and use CMOS gates to build a ring

I am using a MC14060BCP as a oscillator and counter. A 3.XXXMhz crystal
is being connected to pin 10 and 11 with RC circuit. However, I need a
switch that once I simply press the button, it goes to 3.XXXMhz
crystal. If I press the same button for 5 second, it can be switched to

i got a quote for 1 pcb prototype for $657 (1day), $525 (3day) $289 (1
week), a run of 25 (the amount I need) for $416 (1 week), tempting to
skip the prototype eh?

I thought some of you at sci-electronics would find this a bit
interesting, all history cites relating to when was the first television
broadcast in Berlin, often say "1935" were point at which broadcasts
began, but I found an article dated July, 1935 which someone kindly

The dividers and the phase detector of my experimental frequency synthesizer
are implemented in a 15ns Altera MAX7000S CPLD.  I've tried different
multiplication factors (kN) to see how the close-in phase noise varies.  At
a 1 KHz offset, I get:

... is newly available for free download.
It is on a universal .BMP Format Bitmap Image Manipulator and is
accessed via http://www.tinaja.com/glib/unibmpm1.pdf
Companion utilities available as http://www.tinaja.com/psutils/unibmm01.psl

I'd like to make something that seems quite simple but not sure the
best avenue. I basically want to take 64 LEDs and position them in an
8x8 matrix and have them powered by a plug adapter. I'd probably use an
AC adapter. Is this as simple as wiring in series or parallel with