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.
current transformers
Nov 05, 2006
7 Replies
try this
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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
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"
Baron:
"Craig" Hi everyone.
** F*ck OFF - Google MORON !!F*ck, f*ck f*ck f*ck f*ck - OFFFFFFFFF
...... Phil
dont you mean
martin
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..
"I\'m never wrong, once i thought i was, but was mistaken"
Real Programmers Do things like this.
http://webpages.charter.net/jamie_5
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.
martin griffith a écrit :
You're hexasperating... And to do so he has to turn his par(i)ty bits to one more digit.
Thanks,
Fred.
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