I am building some power supplies... Specifically a +/- 15VDC and most likely a thirty something. I have ordered some regaltors... fixed 15+ and fixed 15- and a pair of variables in + and - also.
Is there some regualtor out there that can do both the positive and the negative?
What are your favorite regulators?
Is there some regualtor out there that can do both the positive and the negative?
What are your favorite regulators?
When I designed power supplies back in the 70's there were lots of linear regulators available. Motorola had a chip that did +/- 15V that could be expanded for additional current. Today they're only interested in low voltage stuff for cell phones and PC's.
You won't find much except 3 terminal devices for 15V. Fixed LM7815 / 7915 or variable LM317 / 337 etc.
My favorite is still the venerable LM723 adjustable with series pass transistors.
You won't find much except 3 terminal devices for 15V. Fixed LM7815 / 7915 or variable LM317 / 337 etc.
My favorite is still the venerable LM723 adjustable with series pass transistors.
Do you mean to say that IN/OUT/Grnd on a three pin regulator are relative?
My question refers to Pedja's or Monster's regulated supply.
pedja's supply
Monster's
So the LT1083 and LM338 will regulate negative voltage if supplied with negative voltage????
My current project is using some 7815/7915 regulators. Why should one bother with complementary parts when it could be handled with a single part on both sides?
My question refers to Pedja's or Monster's regulated supply.
pedja's supply
Monster's
So the LT1083 and LM338 will regulate negative voltage if supplied with negative voltage????
My current project is using some 7815/7915 regulators. Why should one bother with complementary parts when it could be handled with a single part on both sides?
Don't be silly. Think of a positive regulator/rectifier/transformer as a black box with two output terminals. Which one you ground is up to you so you can have either positive or neg output.
In the above setup you need two rectifiers and two independent transformer secondaries. It will be quite obvious if you actually look at Pedja's circuit in your link.
But it does. In many situations you have to use a centre-tapped transformer. And you save a bridge rectifier.
It seems though that in practice the complementary regulators are not quite identical - the positive often perform better than the negative. In such situations using a positive regulator for both rails is better.
using positive reg. for negative supply
Hi fellas,
I bought a pair of LT1086 positive adjustable regs. on the advice of some net page claiming it wraps rings around the old 317. The data sheet from LT actually shows how a full range supply can be built by using just positive regs. Here is one design which I adapted from the data sheet. I plan to use it for chip pre amp and head phone amp, and a spare for tone control (shock horror!), hence three outputs. The rails are +/- 18v from a 2x18v transformer. The only thing I might add is AC filter before the bridge.
Hope this helps.
KK
Hi fellas,
I bought a pair of LT1086 positive adjustable regs. on the advice of some net page claiming it wraps rings around the old 317. The data sheet from LT actually shows how a full range supply can be built by using just positive regs. Here is one design which I adapted from the data sheet. I plan to use it for chip pre amp and head phone amp, and a spare for tone control (shock horror!), hence three outputs. The rails are +/- 18v from a 2x18v transformer. The only thing I might add is AC filter before the bridge.
Hope this helps.
KK
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