KD5ZXG Regular Member
 Joined: 21/01/2022 Location: United StatesPosts: 53 |
Posted: 07:21am 21 Jan 2022 |
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1N4148 clipping diodes have lower dynamic resistance than matches 75 ohm cable. It gives a good voltage, but maybe also standing waves and echos.
180 over 150 divider calculates better match to 75 w similar voltage at the far end. 270 for Green's MSB, 270 + 270 = 540 for Green's LSB, all together over 150.
I've calculated even closer values if you have a stash of E96 series.

Fair warning: I've only simulated, not yet tested these values. My Pico won't output higher than 3V when driving an LED, which may not be a safe assumption it would output the same when VGA DAC is the load.
I cut one end off an old VGA cable only to have trouble getting solder to wet the ground braids. Aluminum or stainless I don't know? But it's most annoying to have ruined a cable I now maybe can't use. Edited 2022-01-21 17:44 by KD5ZXG |