Hi !
I have a SP14 preamp and I noticed that the chemical capacitor after the diode bridge was connected on + to a resistance with a small coil on it. It's a RL circuit.
This resistance is not on the diagram of the SP14 but I noticed it on a schematic of the Audio research LS5.
Does anyone know what exactly is the coil resistance and what is his interest?
thanks
I have a SP14 preamp and I noticed that the chemical capacitor after the diode bridge was connected on + to a resistance with a small coil on it. It's a RL circuit.
This resistance is not on the diagram of the SP14 but I noticed it on a schematic of the Audio research LS5.
Does anyone know what exactly is the coil resistance and what is his interest?
thanks
Inrush current limiter. You'll either need to look up the ESR in the inductor's datasheet, measure it, or make reasonable guesses from context. Its contribution to the source impedance to the load is likely minor or negligible compared to R81 and I'd be surprised if it does much that's meaningful to the supply's line interactions after startup.
This is a patented circuit to improve the capacitor's impedance.
Patent US5036292 - Decoupled electrolytic capacitor - Google Patents
At high frequencies the output impedance of the cap bank is that of the capacitor's ESLs in parallel, including layout. Adding more inductance to one of them increases the impedance per Kirchoff's laws as usual, which is not significant in supplying the regulator normal operation with four smaller caps paralleled closer in (particularly in a circuit like this with a 100 ohm series resistor). It is significant at startup for managing the power pulled through the trafo.
DA is negligible in this; you can see for yourself if you like by sweeping the parallel resistances in Spice.
DA is negligible in this; you can see for yourself if you like by sweeping the parallel resistances in Spice.
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