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Electronics => Beginners => Topic started by: Chris Wilson on February 06, 2022, 12:05:24 pm

Title: Questions re building a 5V linear power supply
Post by: Chris Wilson on February 06, 2022, 12:05:24 pm

I would like to build a small very electrically quiet  power supply to run several (perhaps 4) KiwiSDR receivers. They draw a maximum instantaneous current of 2 Amps each, but idle at far less. I can't see any 5V voltage regulators that would handle more than 2 Amps, so if I used an adequately rated transformer could I use several  5V at 2 Amp regulators on the same secondary winding and have multiple output sockets? Or would I be better with one regulator and a big pass transistor? Thanks.

Title: Re: Questions re building a 5V linear power supply
Post by: Zero999 on February 06, 2022, 12:42:25 pm

There are many:
L78S05
LM350
LM338

I'd go for switched mode with loads of filtering.

Title: Re: Questions re building a 5V linear power supply
Post by: mariush on February 06, 2022, 12:47:00 pm

Plenty of linear regulators that can do 2A  ...
For example a very common one is LM1085 and other *1085 (made by other companies), it can do 3A : https://www.digikey.com/en/products/filter/pmic-voltage-regulators-linear/699?s=N4IgTCBcDaIIwAYAcBWEBdAvkA (https://www.digikey.com/en/products/filter/pmic-voltage-regulators-linear/699?s=N4IgTCBcDaIIwAYAcBWEBdAvkA)
*1084 is rated for 5A : https://www.digikey.com/en/products/filter/pmic-voltage-regulators-linear/699?s=N4IgjCBcoLQExVAYygFwE4FcCmAaEA9lANogCsIAugL7X4KSlgAMAHACxX4BsiIAlgBMoIGCwj4ADqhEh8qAJ6TsIgIYBnFLSA (https://www.digikey.com/en/products/filter/pmic-voltage-regulators-linear/699?s=N4IgjCBcoLQExVAYygFwE4FcCmAaEA9lANogCsIAugL7X4KSlgAMAHACxX4BsiIAlgBMoIGCwj4ADqhEh8qAJ6TsIgIYBnFLSA)

Another good one is MIC29310, MIC29301  ... and you have adjustable regulators that do more than 2A : https://www.digikey.com/short/zn72rhmw (https://www.digikey.com/short/zn72rhmw)

Another option would be to use a step-down / buck dc-dc converter - you can buy such converters ready made from eBay for 1-2$ or you could make your own with a chip, an inductor, maybe a diode and a bunch of small ceramic capacitors and resistors.
If you get synchronous rect. chips the diode may not even be needed... .see for example AP62300, look at datasheet as you have shematic on first page for 5v output : https://www.digikey.com/en/products/detail/diodes-incorporated/AP62300TWU-7/12702558 (https://www.digikey.com/en/products/detail/diodes-incorporated/AP62300TWU-7/12702558)

It will also be 90% efficient so you could use a 12v adapter and not worry about dissipating half of the power as heat in a linear regulator

Title: Re: Questions re building a 5V linear power supply
Post by: ledtester on February 06, 2022, 12:51:14 pm

I would suggest looking at getting a commercial unit such as this one:

Power-One HN5-9/OVP-A Power Supply 5VDC 9A w/ OVP 100/120/220/230/240V
https://www.ebay.com/itm/154600988372 (https://www.ebay.com/itm/154600988372)

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