Re: Variable power control

Jerry Gaffke

Yes, a switcher is much more efficient than a linear regulator,
but amps of current getting switched at one mhz or so can create hash you hear in the receiver if 
not properly filtered and shielded.   I can receive well using a desktop 12v brick meant for use with a monitor, 
it is also a switching power supply, so it may be possible to use that ebay buck converter.

Another possibility is to normally power from 12dc, and enable a boost converter to generate 24v
only when transitting. Many switcher chips have an enable pin, though I don't see an enable 
talked about on most of the board level products available on the web.

Much of the rig power during receive is going to the Nano and display and si5351.  
Could cut that significantly with a 12 to 3.3v buck switcher (using 3.3v display and processor)
if you could get it clean enough.

Jerry, KE7ER

On Tue, Jan 2, 2018 at 01:47 pm, Jack Purdum wrote:
Why can I have a 24V supply and use this:    ebay # 152837387238
to drop the voltage to 5V? It seems that less power goes up in heat using one of these, so why won't these work?

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