# 24V dual regulated power supply

I want to build a 0 - 24V dual( + & - ) regulated power supply. My problem is that I am not sure which transformer to use. The purpose of the power supply is as lab power-supply.

I intend on using the LM317 and LM337 as regulators with all necessary filters and such. Just not sure about the transformer. The Primary Voltage is 230V @ 50 Hz.

Any suggestions?

Edit: Schematic

• Schematic?????? – Leon Heller Mar 7 '13 at 15:30
• This is a really tall order for a linear regulator. First, you're not going to get 0-24V. The LM317 regulates down to 1.2V. Second, assuming your transformer and its filtering gives you 2V headroom, at the minimum voltage and max current, $P=VI=(26-1.2V)(1A)=24.8W$ Getting rid of that much heat is going to be a challenge. – Matt Young Mar 7 '13 at 16:16
• @MattYoung That wasn't his question. Also, look at the datasheet carefully. The LM317 can't drop 1A down by 20 something volts. The canonical rating is power dissipation. – Chintalagiri Shashank Mar 7 '13 at 17:36
• @ChintalagiriShashank I am simply pointing out a problem that I see from experience. – Matt Young Mar 7 '13 at 18:00
• @LeonHeller updated schematic. – Eujean Snyman Mar 7 '13 at 18:40