As a future project I'm working on a very small holemounted super regulator with 115/230 volts in and +- 15 volt out. There will be no problem to change the voltage down to 3.3 volts.
If you want to take a peek at the schematics, see below.http://sjostromaudio.com/hifi_files/jsr/jsr06r0schema_p1.pdfhttp://sjostromaudio.com/hifi_files/jsr/jsr06r0schema_p2.pdfhttp://sjostromaudio.com/hifi_files/jsr/jsr06r0schema_p3.pdf
The design goal is a ready unit for drivning a preamp or similar, 230 volt in and ultra low noise stabilized voltage out. The power supply will be very easy to build. It's possible that I will be able to offer ready built units but I won't promise anything.
An another goal is to make the unit a small as possible with chosen parts.
Of course will the pcb look like all my other designs, very high industrial quality with thick copper and groundplane.
The schematic is ready but not the pcb layout. When the pcb is made I want one to three beta builders. A good job will be rewarded.
I'll expect that I will have the pcb manufactured sometime in the second half of 2005.
1 Regulator section identical to my JSR03 and JSR05 but they are snubberized*1) but both the preregulator and the series pass transistor will be on the same heatsink.
2 Option for LM431 or LM385, LM329 or simlilar types of voltage references.
3 Option for DIL08 or SO08 opamps
4 Expected output current max 200 mA (not verified yet how much which is possible).
5 The rectification can be done with an ordinary rectifier bridge or with fast recovery diodes in TO220 package or other types which will fit.
6 The charge currents are limited with a small resistance, reducing harmonics in the rectified DC voltage.
7 The smoothing caps may be ordinary ones or 10 mm snap-in high performance types.
8 The transformer is a 10 VA low profile type with 2 x 115 volt primairies which can be connected for 115 or 230 volts AC
9 The transformer is protected against transients with a varistor VDR.
The PCB will have WAGO connectors and there will be an option for rather thick wires also soldered directly into the board.
*1) A combination of 100 uF in parallel with 100 nF creates two resonances', one peak and one dip. If you insert a small resistance in this circuit you can remove or at least reduce the peak. The peak occurs at a couple of MHz.