Folks...digikey has a UK subsidiary....or at least a UK website....
http://dkc1.digikey.com/uk/digihome.html
http://dkc1.digikey.com/uk/digihome.html
Many modern mosfets have a continous breakdown voltage of 30V....
Of course you don't want to even approach that.
22V secondarys (quite common), should give roughly 28V across your reservoirs...(ripple troughs!)
Allow for 15V gate drive, and drop the rest across your zener regulator and gate drive circuit.....
Of course you don't want to even approach that.
22V secondarys (quite common), should give roughly 28V across your reservoirs...(ripple troughs!)
Allow for 15V gate drive, and drop the rest across your zener regulator and gate drive circuit.....
Upupa Epops said:To Mike : 25 V AC give cca 35 V DC - do you know any mosfet, which have breakdown voltage of Vgs over 20 V ? You don't need for this circuit regulated voltage, only rectifier + filtration.
Remember transformer regulation can be as bad as 30%...!!
This has to be accomodated...
I would say minimum 18V rms secondarys...
Hi mikeks,
I didn't say tough to build. Just more complexity since the detection circuits are the same. Anyhow, I'm positive it'll work as advertised.
Any though to leaving the front end energized to eliminate turn on and off thumps? Just an idea. Esp. if you have a regulated, separate supply for the front end. I would expect that from a design with this much forethought.
Build on McDuff!
-Chris
I didn't say tough to build. Just more complexity since the detection circuits are the same. Anyhow, I'm positive it'll work as advertised.
Any though to leaving the front end energized to eliminate turn on and off thumps? Just an idea. Esp. if you have a regulated, separate supply for the front end. I would expect that from a design with this much forethought.
Build on McDuff!
-Chris
I will disagree on two points.
Firstly, there are no great current transients in the front end. Therefore no line sag and no lost in headroom.
Secondly, dynamic supply shifts can cause small operating point shifts. High frequency noise is another nasty we like to block. Before you start with current sources, I use them too and have made some mighty quiet preamps and front ends. Each of them improved with supply regulation and lead dress.
Please understand I'm not trying to be a critic. It's just my practical experience differs from yours apparently. With most of us chasing the last bit of performance on barely audible issues, I believe this qualifies.
Another point. You will not find a single piece of good electronic test equipment made without attention paid to the supply and it's regulators. Why should an audio amplifier deserve any less? Or should we just copy the analog stages of test equipment and call those superior to what we are building?
-Chris
Firstly, there are no great current transients in the front end. Therefore no line sag and no lost in headroom.
Secondly, dynamic supply shifts can cause small operating point shifts. High frequency noise is another nasty we like to block. Before you start with current sources, I use them too and have made some mighty quiet preamps and front ends. Each of them improved with supply regulation and lead dress.
Please understand I'm not trying to be a critic. It's just my practical experience differs from yours apparently. With most of us chasing the last bit of performance on barely audible issues, I believe this qualifies.
Another point. You will not find a single piece of good electronic test equipment made without attention paid to the supply and it's regulators. Why should an audio amplifier deserve any less? Or should we just copy the analog stages of test equipment and call those superior to what we are building?
-Chris
anatech said:
More to do with voltage transients...an unregulated supply can give vastly greater voltage swing,...on a transient basis, beyond its nominal voltage....than a regulated supply....
Hence the increase in dynamic headroom...
anatech said:
On the contrary, current sources should never be entirely relied upon for good psrr...
This is because their effectiveness declines pro rata with frequency, due to their internal parasitic reactances...
The active loads must therefore be complemented with good old fashioned C-R filtering...
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