LT1963 - Pre Regulation

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
Hi there,

After reading the linear-audio test about different powersupply's, i'd like to test the LT1963 in my preamp.

The preamp needs +18v and -18v. Rotel puts in 7818/7918 as standard regulators.
And the input voltage on the 78/79 is around 22volt.

The LT1963 has a maximum input of 20v.
Is it wise to use the 7818 as a pre regulator and after that let the LT1963 regulating around 17v?

Or are there any other better solutions?
 
Use diodes in series to drop out 2v or so? //Maybe use mosfet, one common type mosfet should dropout enough voltage.
How do you plan to regulate negative rail then?
Is the trafo with dual secondaries? If it is, use the regulator you wanted to with both rails, something like in attached schematic. (Don't pay attention to missing elements and using LM317 macro.)
 

Attachments

  • NONAME.JPG
    NONAME.JPG
    37.1 KB · Views: 1,092
Last edited:
LT3015 is negative reg. I am working on 317/337 to drop enough voltage to safely provide the appropriate Vin to 1963/3015

That setup works really well. I'm using it on this project

http://www.diyaudio.com/forums/head...ersion-o2-desktop-amp-oda-18.html#post3566463 (schematic is first picture, power supply section at the top)

with the 317/337 pre-regulators set up to produce +/-18.5Vdc, then the LT1963A/LT3015 produce +/-16Vdc (and +/-7Vdc, two switch positions) as the final regulators.

The LT LDO's only need around 0.5Vdc drop, so for the OP's circuit he could do the same and set the pre-regs at 18.5Vdc. That would still leave 3.5V across the LM's, which is probably about the minimum. I usually try for at least 5V across them to hit all the datasheet ripple specs.
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.