Some time ago the use of Fast Recovery Epitaxial Diodes (FRED, e.g. Fairchild’s “Stealth” diodes) were popular here to minimize switching noise from the PSU in the audio system. Low reverse recovery current and extremely soft recovery apparently are features that did the trick.
I’d like to try in some projects, most notably a phono preamp and a power amplifier.
I wonder about the power ratings of these devices though. Clearly they were designed with quite different applications in mind, most notably hard switching, high frequency stuff like flyback diodes and other switching power supply applications. Not the kind of linear PSU that I’m thinking of.
Power ratings of these tend to be high (but appropriate for the intended application): starting at 300V or 600V and current ratings ranging from around 10 up to several tens of amps. Compared to these ratings, the actual power consumption in my projects are negligible, virtually zero. Especially in the phono preamp.
When choosing these devices for a linear PSU for audio applications: does the power rating matter at all? Or is it entirely irrelevant? Would it make no practical difference choosing a 30 amp unit over an 8 amp unit?
I’d like to try in some projects, most notably a phono preamp and a power amplifier.
I wonder about the power ratings of these devices though. Clearly they were designed with quite different applications in mind, most notably hard switching, high frequency stuff like flyback diodes and other switching power supply applications. Not the kind of linear PSU that I’m thinking of.
Power ratings of these tend to be high (but appropriate for the intended application): starting at 300V or 600V and current ratings ranging from around 10 up to several tens of amps. Compared to these ratings, the actual power consumption in my projects are negligible, virtually zero. Especially in the phono preamp.
When choosing these devices for a linear PSU for audio applications: does the power rating matter at all? Or is it entirely irrelevant? Would it make no practical difference choosing a 30 amp unit over an 8 amp unit?
Well thank you Andersonix.Very interesting. I find that one of the few disadvantages of living under a rock is that you also miss the good things that come to pass.
I will forget about my ancient diodes and build an ideal rectifier with the LT4320 controller. This here is a great example that follows the data sheet closely. Will draw and order something similar. Looks beautiful in LTSpice.
Still, my question remains relevant also for the active rectifier. The mosfets recommended by the member who built the board linked to above recommends a list of Toshiba and ONsemi mosfet. These are all devices built for typical power electronics applications - just like those ancient FRED diodes. My simulations run fine with some of the Toshibas. But the loads are tiny compared to what these devices are built for. I mean 100+ Amp at 75V... My phono preamp draws several tens of miliamps. I suppose it's safe to say that the mosfets will run coolly.
I will forget about my ancient diodes and build an ideal rectifier with the LT4320 controller. This here is a great example that follows the data sheet closely. Will draw and order something similar. Looks beautiful in LTSpice.
Still, my question remains relevant also for the active rectifier. The mosfets recommended by the member who built the board linked to above recommends a list of Toshiba and ONsemi mosfet. These are all devices built for typical power electronics applications - just like those ancient FRED diodes. My simulations run fine with some of the Toshibas. But the loads are tiny compared to what these devices are built for. I mean 100+ Amp at 75V... My phono preamp draws several tens of miliamps. I suppose it's safe to say that the mosfets will run coolly.