[RFI] Low Voltage Lighting Questions

[Jim Brown]

On 3/30/2018 10:54 AM, Jim Stahl via RFI wrote:
> Is 12 volts DC a common or standard low voltage level? What is the approximate DC current per bulb, i.e. if I were to replace the RFI generating switching supply with a linear supply, how big of a supply would normally be needed?

I can answer part of this. I'm lighting my shack with five strips of 
LEDs powered from the shack's 12V system (a float-charged Costco deep 
discharge battery). Together they draw about 1.2A I have two of these 
strips mounted behind me on a room divider to illuminate my computer 
desk for reading print. They're fed by a linear wart rated 12V/500mA, 
and the wart is barely warm to the touch.

https://www.wiredco.com/LED_Strip_Light_12_Volts_SMT_Cool_White_20_p/ledbar1.htm

https://www.wiredco.com/LED_Lighting_Low_Voltage_s/1874.htm

This company has been at west coast hamfests for at least 5 years. In 
general, their electronics stuff is crap (noisy SMPS, a USB FM modulator 
that spews noise sidebands, crummy knock-off connectors and patch 
cables), but the lighting that doesn't include power supplies is very nice.

And this observation. Depending on how dimming is accomplished, it could 
also be adding noise to what the SMPS is producing. My guess is that 
you'll need ferrite chokes on wiring between the PSU and the AC line. 
The good news is that the current is quite low, especially on the 120V 
side, so small conductors on small cores can be used. If you're going to 
build something to fit inside an existing fixture, be sure to use wire 
with insulation rated for use on AC mains.

If you would like some design help with chokes, shoot me a private email 
and we can talk about it.

73, Jim K9YC