1.0Circuit Globehttps://circuitglobe.comArchana Thttps://circuitglobe.com/author/authorrich600338<blockquote class="wp-embedded-content" data-secret="6S8RRFT6X1"><a href="https://circuitglobe.com/vacuum-tube-voltmeter-vtvm.html">Vacuum Tube Voltmeter (VTVM)</a></blockquote><iframe sandbox="allow-scripts" security="restricted" src="https://circuitglobe.com/vacuum-tube-voltmeter-vtvm.html/embed#?secret=6S8RRFT6X1" width="600" height="338" title="“Vacuum Tube Voltmeter (VTVM)” — Circuit Globe" data-secret="6S8RRFT6X1" frameborder="0" marginwidth="0" marginheight="0" scrolling="no" class="wp-embedded-content"></iframe><script> /*! This file is auto-generated */ !function(c,d){"use strict";var e=!1,o=!1;if(d.querySelector)if(c.addEventListener)e=!0;if(c.wp=c.wp||{},c.wp.receiveEmbedMessage);else if(c.wp.receiveEmbedMessage=function(e){var t=e.data;if(!t);else if(!(t.secret||t.message||t.value));else if(/[^a-zA-Z0-9]/.test(t.secret));else{for(var r,s,a,i=d.querySelectorAll('iframe[data-secret="'+t.secret+'"]'),n=d.querySelectorAll('blockquote[data-secret="'+t.secret+'"]'),o=new RegExp("^https?:$","i"),l=0;l<n.length;l++)n[l].style.display="none";for(l=0;l<i.length;l++)if(r=i[l],e.source!==r.contentWindow);else{if(r.removeAttribute("style"),"height"===t.message){if(1e3<(s=parseInt(t.value,10)))s=1e3;else if(~~s<200)s=200;r.height=s}if("link"===t.message)if(s=d.createElement("a"),a=d.createElement("a"),s.href=r.getAttribute("src"),a.href=t.value,!o.test(a.protocol));else if(a.host===s.host)if(d.activeElement===r)c.top.location.href=t.value}}},e)c.addEventListener("message",c.wp.receiveEmbedMessage,!1),d.addEventListener("DOMContentLoaded",t,!1),c.addEventListener("load",t,!1);function t(){if(o);else{o=!0;for(var e,t,r,s=-1!==navigator.appVersion.indexOf("MSIE 10"),a=!!navigator.userAgent.match(/Trident.*rv:11\./),i=d.querySelectorAll("iframe.wp-embedded-content"),n=0;n<i.length;n++){if(!(r=(t=i[n]).getAttribute("data-secret")))r=Math.random().toString(36).substr(2,10),t.src+="#?secret="+r,t.setAttribute("data-secret",r);if(s||a)(e=t.cloneNode(!0)).removeAttribute("security"),t.parentNode.replaceChild(e,t);t.contentWindow.postMessage({message:"ready",secret:r},"*")}}}}(window,document); </script> The voltmeter which uses the vacuum tube for amplifying the measurand AC and DC voltage is known as the vacuum tube voltmeter (VTM). The VTM is used for measuring the voltage of direct, RMS and peak voltage of the network.https://circuitglobe.com/wp-content/uploads/2017/09/vacuum-tube-voltmeter.jpg