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Audio and Video Talk
Valves / Vacuum Tubes
testing tube voltage in circuit
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<blockquote data-quote="handsome" data-source="post: 1027170" data-attributes="member: 772"><p>All capacitors are just two conducting metal (invariably aluminum) plates separated by an insulator (called a dielectric). The amount of capacitance is determined by the size of the plates, the distance between them and the properties of the insulator. So dielectric properties aside, a capacitor's capacitance is down to physical size and relative position of it's plates. So be wary therefore, of judging a capacitor's age/quality on just it's measured capacitance value alone. Since an ideal capacitor would have zero resistance (not impedance) and inductance (but real world materials have resistance, the need to roll the rather large plates and insulator up into a smaller package adds inductance as do the leads whilst- </p><p>rather more arcane effects like dissipation factor are due to the insulator's material properties), a capacitor's effective series resistance or ESR can be a good indicator of a capacitor's viability. This is especially true for electrolytic capacitors as they have wet dielectrics which can and do evaporate as opposed to those expensive paper and oil buggers (yes yous Jensen, AudioNote, Jupiter et al) just always go leaky on me.....</p><p>.</p></blockquote><p></p>
[QUOTE="handsome, post: 1027170, member: 772"] All capacitors are just two conducting metal (invariably aluminum) plates separated by an insulator (called a dielectric). The amount of capacitance is determined by the size of the plates, the distance between them and the properties of the insulator. So dielectric properties aside, a capacitor's capacitance is down to physical size and relative position of it's plates. So be wary therefore, of judging a capacitor's age/quality on just it's measured capacitance value alone. Since an ideal capacitor would have zero resistance (not impedance) and inductance (but real world materials have resistance, the need to roll the rather large plates and insulator up into a smaller package adds inductance as do the leads whilst- rather more arcane effects like dissipation factor are due to the insulator's material properties), a capacitor's effective series resistance or ESR can be a good indicator of a capacitor's viability. This is especially true for electrolytic capacitors as they have wet dielectrics which can and do evaporate as opposed to those expensive paper and oil buggers (yes yous Jensen, AudioNote, Jupiter et al) just always go leaky on me..... . [/QUOTE]
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Audio and Video Talk
Valves / Vacuum Tubes
testing tube voltage in circuit
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