Electronics > Projects, Designs, and Technical Stuff
0-70V, 0-5A Lab Power Supply Design
Miyuki:
I have a lab supply what have classic output range 2x 36V 2A with specified 1mVpp ripple output and some fixed outputs +-15V with 2mV ripple at full load
It uses thyristor preregulator with linear post regulator
But it is huge beast and as new cost a fortune and there is not much what can be done smaller when want do it linear with mains transformer and reliable
schmitt trigger:
You don't need a custom transformer to achieve several raw DC voltages, just a dual secondary transformer and a bunch of relays:
Low range: secondaries in parallel, FW bridge rectifier
Mid range: secondaries in series, FW bridge rectifier
High range: secondaries in series, voltage doubler rectifier
I'll let you figure out the relay switching logic. Probably best achieved with a small microcontroller.
H713:
Ripple isn't a huge deal up at 70V, and I should have mentioned that it is much more of a concern in the 24V range where it will likely be used to test class-A mixing console circuits. Given that the 0-500V linear supply I built had ripple below 10mV under load, I feel that I should be able to get this significantly lower.
I should note that I have decided to build this rather than purchase a Sorensen or Xantrex PSU because going onto eBay and clicking "Buy" isn't much of a design exercise, is it?
Regarding noise from the Triac/SRC "dimmer" pre-regulator: I was going to use an LC network to try and filter out the worst of the high-frequency noise before the primary of the main transformer. That said, I will be looking more seriously into tap switching since it is a much simpler solution.
I can try a doubler circuit for the high range, but I suspect that the voltage sag under load will be problematic unless I use excessively large filter capacitors. I need to do a few calculations to see if it's going to be realistic. If it is, that solves the problem.
David Hess:
Since I try not to require regulated supplies for my audio power amplifiers, I use a conventional unregulated transformer/rectifier/capacitor power supply preceded by a variac for testing.
H713:
I should note that while the primary use for this will be audio power amplifiers, it will see use for testing other more sensitive circuits. As an example, class A mixing console circuits operating on +45V rails. It's still probably overkill, but I think it will be an interesting challenge to design.
Navigation
[0] Message Index
[#] Next page
[*] Previous page
Go to full version