A linear voltage regulator is very quiet. That's just a bipolar transistor passing the current with adjustable base voltage. I use them on my HB power supplies for the same reason. No square switching, no RFI.
73, Ron AC7AC -----Original Message----- From: Elecraft [mailto:[email protected]] On Behalf Of Bill Frantz Sent: Friday, January 6, 2017 6:07 PM To: [email protected] Subject: Re: [Elecraft] Dimmable LED desk lamp for operating position recommendation needed To avoid color shifts with dimming, most LED dimmers use Pulse Width Modulation (PWM). PWM has the potential to generate RFI, so be careful. The LEDs themselves should be very quiet. Using LEDs with resistors to limit the current should also be quiet. A system that switches LEDs for brightness control would be a safe solution, but I don't know of any commercial systems which do this. On the other hand, I have not noticed a problem with the LED dimmers in my house, so perhaps most of the problem is in the wall-wart power supply. 73 Bill AE6JV On 1/6/17 at 3:50 AM, [email protected] (Marc Veeneman via Elecraft) wrote: >I mounted (dual side adhesive tape) an LED strip to the underside of an >equipment shelf. The strip came with a 12v switcher that I ignored. I >use my 12 volt supply. The strip was, I think, 24 inches long and has >a dimmer that can be inserted in the power lead. No RFI. Plenty >bright. Mine came from Amazon but there are many to choose from these >days; you can even select color temperature when you order. ----------------------------------------------------------------------- Bill Frantz | Truth and love must prevail | Periwinkle (408)356-8506 | over lies and hate. | 16345 Englewood Ave www.pwpconsult.com | - Vaclav Havel | Los Gatos, CA 95032 ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
