current transformers

[Craig]

Hi everyone.
COuld anyone help me with a problem I am having interfacing a current
transformer to a PC. I have a 50/5A curent transformer which, via a
ballast resistor produces the usuual variable AC Voltage on the
secondary. My problem is I need this AC converting to 0 to 2.5V DC to
power the PC interface and I am having great trouble coverting it. The
normal diodes/bridge rectifier don't seem to work. I suspect this could
be to do with losses in the diodes but my electronic know-how doesn't
streatch this far. Any help would be greatly appreciated.

 

[martin griffith]

Hi everyone.
COuld anyone help me with a problem I am having interfacing a current
transformer to a PC. I have a 50/5A curent transformer which, via a
ballast resistor produces the usuual variable AC Voltage on the
secondary. My problem is I need this AC converting to 0 to 2.5V DC to
power the PC interface and I am having great trouble coverting it. The
normal diodes/bridge rectifier don't seem to work. I suspect this could
be to do with losses in the diodes but my electronic know-how doesn't
streatch this far. Any help would be greatly appreciated.

try this
http://sound.westhost.com/appnotes/an001.htm
you will need a negative supply for the opamps, despite the output
only going positive.
You may need a reverse biased diode across the input of the ADC, 1n914
etc, to stop any -ve volts on powerup


martin

 

[Baron]

Hi everyone.
COuld anyone help me with a problem I am having interfacing a current
transformer to a PC. I have a 50/5A curent transformer which, via a
ballast resistor produces the usuual variable AC Voltage on the
secondary. My problem is I need this AC converting to 0 to 2.5V DC to
power the PC interface and I am having great trouble coverting it. The
normal diodes/bridge rectifier don't seem to work. I suspect this
could be to do with losses in the diodes but my electronic know-how
doesn't
streatch this far. Any help would be greatly appreciated.

What frequency range are we talking about ?
What are you doing to convert the output ?
What is the input impedance of the PC interface ?
A schematic would help ! Post it to
"alt.binaries.schematics.electronics"

 

[Phil Allison]

"Craig" <[email protected] wrote in message

Hi everyone.

** **** OFF - Google MORON !!

****, **** **** **** **** - OFFFFFFFFF






....... Phil

 

[neon]

you need to amplify the signal diodes drops will elininate your signal at low current it disconnect. not to mention linearity.

 

[martin griffith]

"Craig" <[email protected] wrote in message




** **** OFF - Google MORON !!

****, **** **** **** **** - OFFFFFFFFF






...... Phil

dont you mean
****, **** **** **** **** - OxFFFFFFFFF

martin

 

[Jamie]

Hi everyone.
COuld anyone help me with a problem I am having interfacing a current
transformer to a PC. I have a 50/5A curent transformer which, via a
ballast resistor produces the usuual variable AC Voltage on the
secondary. My problem is I need this AC converting to 0 to 2.5V DC to
power the PC interface and I am having great trouble coverting it. The
normal diodes/bridge rectifier don't seem to work. I suspect this could
be to do with losses in the diodes but my electronic know-how doesn't
streatch this far. Any help would be greatly appreciated.

you need a precision rectifier and op-amp etc..
didn't you ask for this before?
use a dual op-amp to for a full wave precision
rectifier. in order to get a nice 0 to 2.5 v how ever.,
you should employ a negative rail supply.
DC-DC converter is great for this from a single power
source.. or i suppose you could whip up a DC to DC from a
a 555 timer to get a - voltage regulated , i've done that
before how ever, you will find that a simple single chip
charge pump DC-DC dual rail us most likely less parts count.
unless you pull the trick i've seen before, use an RS-232
port and have output leg off for - voltage, and one on for
+ voltage. and use a min pic to convey the info via rs-232
serial.
just simply use a USB to rs-232 converter ... etc..

 

[John Popelish]

Hi everyone.
COuld anyone help me with a problem I am having interfacing a current
transformer to a PC. I have a 50/5A curent transformer which, via a
ballast resistor produces the usuual variable AC Voltage on the
secondary. My problem is I need this AC converting to 0 to 2.5V DC to
power the PC interface and I am having great trouble coverting it. The
normal diodes/bridge rectifier don't seem to work. I suspect this could
be to do with losses in the diodes but my electronic know-how doesn't
streatch this far. Any help would be greatly appreciated.

This topic was discussed in considerable detail last
September in a thread titled "Help interfacing Current
Transformers to ADC" A Google groups search should give you
a fair head start.

 

[Fred Bartoli]

martin griffith a écrit :
You're hexasperating...
And to do so he has to turn his par(i)ty bits to one more digit.