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What is switching in regard to a power supply?

Mar 10th 2012, 22:00

tscott

Joined: Mar 5th 2012, 02:13
Total Topics: 0
Total Posts: 0
Researching power supplies and see "switching" power supplies.

What is meant by "switching".
Mar 11th 2012, 02:04

AA6E

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
A switching supply generally rectifies the incoming AC (allowing a wide range of input voltage and frequency) and uses the rectified DC voltage to operate an efficient oscillator (usually in the 20 kHz range) using transistors operating in the switching mode (on-off). The 20 kHz voltage runs through a transformer, rectifier and regulator circuits to produce the desired final DC output. Efficiency can be very high because of the switching mode, and weight is low because of the small size transformer. One downside is possible excessive output noise at the 20 kHz switching frequency and harmonics up through the HF bands.

HTH
Martin AA6E
ARRL Technical Advisor
Mar 11th 2012, 03:17

tscott

Joined: Mar 5th 2012, 02:13
Total Topics: 0
Total Posts: 0
Thanksfor the reply. You mention "harmonics up through the HF bands". Is this not a real issue for VHF and UHF then? That will be my application.
Mar 11th 2012, 19:42

AA6E

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Interference is possible at higher frequencies, but the signal strength normally decreases a lot. At 100 MHz, you're talking about the 5000th harmonic of the switch rate. Many switchers are quite useable in the HF range and higher. Check the product reviews or be sure you can return the unit if it causes trouble.

73 Martin AA6E
May 12th 2013, 17:41

K4PP

Joined: Jun 26th 2008, 13:28
Total Topics: 0
Total Posts: 0
I had found this video a while ago with it's details describing a switching supply. This OM really explains it well.
http://www.youtube.com/watch?v=rkApRg5VWnc&feature=related

Paul, K4PP

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