{"version":"1.0","provider_name":"The Circuit Design Blog","provider_url":"https:\/\/www.tina.com\/blog","author_name":"Michael Koltai","author_url":"https:\/\/www.tina.com\/blog\/author\/michael\/","title":"Capacitance Bridge","type":"rich","width":600,"height":338,"html":"<blockquote class=\"wp-embedded-content\" data-secret=\"qOxmxKDKpk\"><a href=\"https:\/\/www.tina.com\/blog\/capacitance-bridge\/\">Capacitance Bridge<\/a><\/blockquote><iframe sandbox=\"allow-scripts\" security=\"restricted\" src=\"https:\/\/www.tina.com\/blog\/capacitance-bridge\/embed\/#?secret=qOxmxKDKpk\" width=\"600\" height=\"338\" title=\"&#8220;Capacitance Bridge&#8221; &#8212; The Circuit Design Blog\" data-secret=\"qOxmxKDKpk\" frameborder=\"0\" marginwidth=\"0\" marginheight=\"0\" scrolling=\"no\" class=\"wp-embedded-content\"><\/iframe><script>\n\/*! This file is auto-generated *\/\n!function(d,l){\"use strict\";l.querySelector&&d.addEventListener&&\"undefined\"!=typeof URL&&(d.wp=d.wp||{},d.wp.receiveEmbedMessage||(d.wp.receiveEmbedMessage=function(e){var t=e.data;if((t||t.secret||t.message||t.value)&&!\/[^a-zA-Z0-9]\/.test(t.secret)){for(var s,r,n,a=l.querySelectorAll('iframe[data-secret=\"'+t.secret+'\"]'),o=l.querySelectorAll('blockquote[data-secret=\"'+t.secret+'\"]'),c=new RegExp(\"^https?:$\",\"i\"),i=0;i<o.length;i++)o[i].style.display=\"none\";for(i=0;i<a.length;i++)s=a[i],e.source===s.contentWindow&&(s.removeAttribute(\"style\"),\"height\"===t.message?(1e3<(r=parseInt(t.value,10))?r=1e3:~~r<200&&(r=200),s.height=r):\"link\"===t.message&&(r=new URL(s.getAttribute(\"src\")),n=new URL(t.value),c.test(n.protocol))&&n.host===r.host&&l.activeElement===s&&(d.top.location.href=t.value))}},d.addEventListener(\"message\",d.wp.receiveEmbedMessage,!1),l.addEventListener(\"DOMContentLoaded\",function(){for(var e,t,s=l.querySelectorAll(\"iframe.wp-embedded-content\"),r=0;r<s.length;r++)(t=(e=s[r]).getAttribute(\"data-secret\"))||(t=Math.random().toString(36).substring(2,12),e.src+=\"#?secret=\"+t,e.setAttribute(\"data-secret\",t)),e.contentWindow.postMessage({message:\"ready\",secret:t},\"*\")},!1)))}(window,document);\n\/\/# sourceURL=https:\/\/www.tina.com\/blog\/wp-includes\/js\/wp-embed.min.js\n<\/script>\n","description":"This circuit is a capacitance bridge; it detects the matching between a reference capacitance C1 and an unknown capacitance, Cx. It uses an instrumentation amplifier in an unusual topology-- a sine wave drives the two input op amps' non- inverting inputs (ordinarily the IA inputs) and the internal 25k feedback resistor of each op amp forces that sine wave to appear at the op amp's inverting inputs (ordinarily the IA gain resistor connections).","thumbnail_url":"https:\/\/www.tina.com\/blog\/wp-content\/uploads\/2015\/03\/Capacitance-Bridge-blog.png","thumbnail_width":413,"thumbnail_height":266}