Electronics Forum / Design / January 2006

I'm looking into a small scale hydro project just to get my feet wet
with renewable energy.  Does anyone have any ideas to share on how to
design an efficient alternator in the 100 to 250 watt range?  I know I
can use motors etc, but I'm interested in knowing how to get the

We are looking for engineering assistance developing a ARM SoC PCB for
a commercial product.
Ideal candidate will be US based, Chicago area a big plus.
Demonstrated experience in pcb design with ARM SoC's, with some

This post contains two related questions.
A few months back, I implemented a prototype ADC (analog) interace
circuit and used a 2 pole sallen-key filter using a Burr Brown opa237
opamp.  Based on my ADC sample freq relative to the cutoff freq a 2

Is there a pot that has a taper in the shape of 1/X if X is greater than
zero and less than 1. I guess you'd call it reciprocal taper.
bg

I have to modify an old circuit, i have to reduce the circuit but i am
finding buffers(Voltage followers) being using after gain section and
before comparator section using Opams. Can these buffers be removed?
Why are buffers used?

It's a need to know sort of thing.
DNA

I messing around reviewing the basics and I came up with some idea about
using a voltage divider to run a load and negative resistance to cancel out
the loading effects... the idea follows
R1

I need to make a controll board for 3 R/C servos by regular
potentiomenters.
The problem I have - I do not know nothing about electronics and how
they work!

Have any one ever used a DS1307 RTC ?
give me the technical tips in handling it and also coding hints to
interface it with Aduc841 microconverter.
Help please.

I'm considering a general purpose 'dimmer'. (more on-off ATM, but the
functionality could be added later).
The power control device would be a 400V FET (that I happen to have
a bag of that a pick and place machine ate half of the drain wire)

Today's Dilbert is pretty good:
http://www.dilbert.com/comics/dilbert/archive/dilbert-20060130.html

I was just sitting here whiling away a Friday afternoon, with the weather
more amenable to having a picnic, and happened to think of some of the
first integrated circuits (ICs) I ever heard of - they were from Motorola,
and ran off 3.6Vdc Vcc, and they were either RTL or DTL, or ...

http://www.sfgate.com/columnists/asmussen/
John

I got a stepper motor translater/driver from allegro (SLA7051M).  I
hooked up the circuit as shown in the data sheet and interfaced it with
a microcontroller to feed the control signals. At first my clock (step)
signal frequency was too high, so i stepped it down A LOT.  Then I was

I'm looking for DTMF decoder chips and I am having a lot of trouble
finding any.
Some of the part numbers I have searched are TDK's SSI-220, or G8870
Any available DTMF decoder will do the job.  Does anyone know a place