TECHFORUM
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92 January 2009
>>> QUESTIONS
Three-Phase Power —
Rotary Phase Converters
Is there a simple design guide
available for calculating proper capacitor
sizes used in the construction of rotary
phase converters that use ordinary three-phase motors as the rotary transformer?
#1091 Jack Kleiss
Cloverdale, IN
Three-Phase Power
Does anyone know of a simple,
inexpensive, but very accurate, way to
monitor three-phase current in brushless motor circuits? The method should
require, at most, one channel of ADC.
#1092 Jack Kleiss
Cloverdale, IN
Video Adapter
I would like to feed the modulated
video output from my DVD player to
a SVGA video monitor. Other than
stripping the modulation from the
signal, I'm not sure what to do next.
#1093 Gary Johnson
Camarillo, CA
Svideo Luminance
I have a DVD player with Svideo
out; I need to build a simple circuit to
use the luminance pins to trigger a relay
as soon as luminance is black.
#1094 Karpis
Los Angeles, CA
One Minute (or More) Timer
I need a way to reliably trigger a
555 from a loss of input signal. I've tried
several schemes involving capacitor
discharge when the input disappears
but they have not proven to be reliable.
Keeping the input high apparently
doesn't let the device time out, so it
needs to be a positive going pulse.
#1095 David Schoepf
Marianna, FL
Logic Analyzer
I have a LEADER Model 300
DMM/scope with logic analyzer. I
need help/info to build an interface
circuit that would allow me to use the
eight channel logic analyzer.
#1096 Jeff Clark
Sardinia, OH
SSR
I would like to know how to
calculate input resistance and design
with a solid-state relay used as a switch.
#1097 Cesar Romero
Leonia, NJ
Humidity Sensor
I am looking for a small humidity sensor circuit powered by 120V that can trigger a relay based on an adjustable
humidity level. My ultimate goal is to
wire it into a bathroom fan and have the
relay trigger an X10 command via an
X-10/Insteon I/O module. The X10 command would turn the fan on or off based
on the humidity in the room and the
