Voltmeter design _ Dc Metering Circuits

# But how do we c reat e t he nec essary proport ioning

This preview shows page 1. Sign up to view the full content.

This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: t ed. But how do we c reat e t he nec essary proport ioning c irc uit ? Well, if our int ent ion is t o allow t his met er movement t o measure a great er volt age t han it does now, what we http://www.allaboutcir cuits.com/vol_1/chpt_8/2.html 1/6 1/22/2014 Voltmeter desig n : Dc M eter ing Cir cuits need is a volt age divider c irc uit t o proport ion t he t ot al measured volt age int o a lesser f rac t ion ac ross t he met er movement 's c onnec t ion point s. Knowing t hat volt age divider c irc uit s are built f rom ser ies resist anc es, we'll c onnec t a resist or in series wit h t he met er movement (using t he movement 's own int ernal resist anc e as t he sec ond resist anc e in t he divider): T he series resist or is c alled a "mult iplier" resist or bec ause it mult iplies t he working range of t he met er movement as it proport ionat ely divides t he measured volt age ac ross it . Det ermining t he required mult iplier resist anc e value is an easy t ask if you're f amiliar wit h series c irc uit analysis. F or example, let 's det ermine t he nec essary mult iplier value t o make t his 1 mA, 500 Ω movement read exac t ly f ull- sc ale at an applied volt age of 10 volt s. T o do t his, we f irst need t o set up an E/I/R t able f or t he t wo series c omponent s: Knowing t hat t he movement will be at f ull- sc ale wit h 1 mA of c urrent going t hrough it , and t hat we want t his t o happen at an applied (t ot al series c irc uit ) volt age of 10 volt s, we c an f ill in t he t able as suc h: T here are a c ouple of ways t o det ermine t he resist anc e value of t he mu...
View Full Document

## This lab report was uploaded on 04/05/2014 for the course ECSE 291 taught by Professor N/a during the Winter '11 term at McGill.

Ask a homework question - tutors are online