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Audio and Video Talk
The Vintage Audio Section
Quad 303 restoration
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<blockquote data-quote="marantz123" data-source="post: 899338" data-attributes="member: 16849"><p>(240v - the volt drop rating of the led) / the current you would like..15mA will give you the resistance. Critical here is the power rating of the resistor. I calculated at 10mA, 240v, 3v led volt drop gives you 24k resistor at 2.5w resistor power rating. But...why not fit a neon lamp..its easier?</p><p></p><p>Calculated at 2mA, you can use a 118k resistor with a 0.5w or better a 1w ressie. Experiment..a bit for the lowest power..maybe 2mA-5mA will be bright enough. Also...resistor voltage rating is critical. Use metal film MRS25 if calc is 0.5w or below, or go with PR01 if 1w or less. This is the basic calc and design but rectifiers and capacitors can be used as well to improve the circuit.</p></blockquote><p></p>
[QUOTE="marantz123, post: 899338, member: 16849"] (240v - the volt drop rating of the led) / the current you would like..15mA will give you the resistance. Critical here is the power rating of the resistor. I calculated at 10mA, 240v, 3v led volt drop gives you 24k resistor at 2.5w resistor power rating. But...why not fit a neon lamp..its easier? Calculated at 2mA, you can use a 118k resistor with a 0.5w or better a 1w ressie. Experiment..a bit for the lowest power..maybe 2mA-5mA will be bright enough. Also...resistor voltage rating is critical. Use metal film MRS25 if calc is 0.5w or below, or go with PR01 if 1w or less. This is the basic calc and design but rectifiers and capacitors can be used as well to improve the circuit. [/QUOTE]
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Audio and Video Talk
The Vintage Audio Section
Quad 303 restoration
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