please dont rip this site

Current Sensing

Bob Blick says:

All you need is seven resistors(six if you have a great collection) and an opamp to do high-side current measurement. If your opamp is a rail-to-rail output type, you can run it on the same supply as your [processor] (5 volts):
Note: I give myself an "0x41" in ascii art!

        0.1R
24in-*--\/\/\/\--*---24out
     |           |
     \           \
     / 1M    1M  /
     \           \
     |           |     10M
     |           *----/\/\/\/----|
     |           |    |\         |
     |           *----|-\        |
     |           |    |  >-------*----  5v=5A
     *-------------*--|+/
     |           | |  |/
     \           \ \
     / 100K  100K/ / 10M
     \           \ \
     |           | |
  ---*-----------*-*-- ground

The voltage dividers(1Meg,100K) lose 11 to 1, but the opamp gain is set at 110, net gain is 10. The opamp's inputs are sitting at about 2.4 volts, so they are quite happy. Use one of them new-fangled Microchip-brand opamps and you're sitting pretty. Expect a little offset error using a circuit with this much gain.

Roman Black says:

Here's a simple suggestion, run two simple resistor dividers from each side of the resistor to GND. These can feed 2 ADC inputs on the [computer]. So instead of measureing 0.5v across the resistor you are measuring 24v and 23.5v both with reference to ground, this is very low parts count and will work fine. Just subtract them in software.

Resolution will be a bit lower, and it uses two ADC inputs, not one. But it might do what you need. :o)

Comments:


file: /Techref/io/sensor/amps.htm, 2KB, , updated: 2005/6/22 18:01, local time: 2024/3/28 04:14,
TOP NEW HELP FIND: 
54.173.229.84:LOG IN

 ©2024 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?
Please DO link to this page! Digg it! / MAKE!

<A HREF="http://techref.massmind.org/techref/io/sensor/amps.htm"> Current Sensors</A>

After you find an appropriate page, you are invited to your to this massmind site! (posts will be visible only to you before review) Just type a nice message (short messages are blocked as spam) in the box and press the Post button. (HTML welcomed, but not the <A tag: Instead, use the link box to link to another page. A tutorial is available Members can login to post directly, become page editors, and be credited for their posts.


Link? Put it here: 
if you want a response, please enter your email address: 
Attn spammers: All posts are reviewed before being made visible to anyone other than the poster.
Did you find what you needed?

 

Welcome to massmind.org!

 

Welcome to techref.massmind.org!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

  .