[Heath] Off Topic Switching Power Supply

[Bill Guyger]

If you Google regulated power supply circuits or 3 amp regulated supplies you'll find schematics that show how to use an external pass transistor to boost the current capability of 78xx regulators. You might want to search LM723 regulator data sheets, they are a universal regulator as are LM317's. The 317 is especially useful since you can make variable voltage supplies very easily. FWIW all the Astron linear supplies are LM723 based.

Don't worry with the hassles of filtering a laptop type supply when it's so easy to do a linear that is inherently quite. Although I must say that the more complex (expensive) switching supplies can be pretty quiet, and pack a lot of current capability into a small box, but for your charging purpose there's no reason to do more than gin up a simple 723 or 317 based circuit.

Bill AD5OL

Sent from my iPhone

> On Nov 1, 2015, at 10:11 PM, Ron <kd6edv at gmail.com> wrote:
> 
> I built an 18vdc 1.5 amp power supply using a transformer, bridge rectifier and a 7818 regulator. Works fine, but I need to go to 3 amps. I have been trying laptop switching power supplies that put out 3 amps that produce noise on my hf rig. If I unplug the laptop power supply, the noise goes away. The power supply is used for charging batteries through a solar charger.
> 
> Questions: what is the difference between a regular power supply and a switching power supply? Can I filter out the noise on a switching power supply?
> 
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