[SI-LIST] AW: question about voltage dividers
- From: "Havermann, Gert" <Gert.Havermann@xxxxxxxxxxx>
- To: "Roy M" <roymesi@xxxxxxxxx>, si-list@xxxxxxxxxxxxx
- Date: Wed, 4 Mar 2009 12:07:49 +0100
Roy,
The resistor values for Voltage dividers should be chosen in regards to the
expexted load.
E.G. if your load is 1k and you use the 3k and 1k resistors (as per your
example) and 1k is in parallel to the load, then the overall voltage ratio is
6:1 (because the load in parallel to R2 gives you 0.5k effective resistance).
If you use the 3M and 1M resistors, you parallel the 1M with the 1k load which
is approx 1k effective resitance, then the voltage ratio is 3000:1.
Ist all about the load. If you have an operational amp with very high input
resistor and no feedback loop, then 3M:1M might work.
BR
Gert
-----Ursprüngliche Nachricht-----
Von: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] Im
Auftrag von Roy M
Gesendet: Mittwoch, 4. März 2009 09:36
An: si-list@xxxxxxxxxxxxx
Betreff: [SI-LIST] question about voltage dividers
HI,
I have a general, rather basic, question concerning voltage dividers.
We all know that when it comes to voltage dividers, the *ratio* between the
resistors is what matters to the Vout value, and not the resistors'
*value*itself.
But if I know for instance, that the ratio is 1:3 (i.e, R1=3*R2), so I can
choose R1 to be 3k and R2 to be 1k, OR I can choose R1=3000k and R2=1000K or
(well, you got my idea...).
Now, I understand that a very low value means high power (cause there's alot of
current going to gnd) but what if I choose very high value? (like 1M and 3M),.
it doesn't sounds good, but I can't explain why..
Help anyone???
Thanks,
Roy
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
- » [SI-LIST] AW: question about voltage dividers - Havermann, Gert
