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Audio and Video Talk
The Vintage Audio Section
LF a power supply for a Nagra 4.2 RtoR tape deck
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<blockquote data-quote="Ampdog" data-source="post: 272104" data-attributes="member: 144"><p>Careful with lamp loads, Mafioso. They draw high current until working at full voltage/brilliance. It could easily be some 5A at cold.</p><p></p><p>I think your supply has a problem starting up, but sadly cannot advise you there. You will have to go the way of a (fixed) load resistor (minimum 75 ohms), perhaps a series of resistors totalling say 10W minimum. One you can vary from a high resistance to lower until the operating load is reached.</p><p></p><p>The point about the capacitor it feeds into is also relevant; again a low start-up impedance as the capacitor charges. Perhaps the existing supply has enough internal filtering capacity. But here you must be careful. Not a high value is needed to achieve proper ripple filtering, but depending on the power supply design, it may scoff at the Nagra's filter capacitor which is there for good reservoir action down to say 30 Hz. </p></blockquote><p></p>
[QUOTE="Ampdog, post: 272104, member: 144"] Careful with lamp loads, Mafioso. They draw high current until working at full voltage/brilliance. It could easily be some 5A at cold. I think your supply has a problem starting up, but sadly cannot advise you there. You will have to go the way of a (fixed) load resistor (minimum 75 ohms), perhaps a series of resistors totalling say 10W minimum. One you can vary from a high resistance to lower until the operating load is reached. The point about the capacitor it feeds into is also relevant; again a low start-up impedance as the capacitor charges. Perhaps the existing supply has enough internal filtering capacity. But here you must be careful. Not a high value is needed to achieve proper ripple filtering, but depending on the power supply design, it may scoff at the Nagra's filter capacitor which is there for good reservoir action down to say 30 Hz. [/QUOTE]
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Audio and Video Talk
The Vintage Audio Section
LF a power supply for a Nagra 4.2 RtoR tape deck
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