technobly / VEXTREME

VEXTREME - Vectrex Multicart
GNU General Public License v3.0
61 stars 12 forks source link

RGB LEDs causing faint buzzing bees noise due to power supply modulation #46

Closed technobly closed 4 years ago

technobly commented 4 years ago

Bug Report

Expected Behavior

For the most part, but totally silent.

Observed Behavior

The LEDs on VEXTREME v0.2 tend to oscillate/modulate at evil frequencies 666hz when the brightness is limited based on the color value 0x0 ~ 0xFF for each R,G,B. When it's not 0xFF, you'll hear this extra buzz.

If you have a no-buzz Vectrex, it will be more obvious. You can't have all 10 LEDs on at full brightness. It's too much current for the Vectrex.

Hardware filtering seems like an obvious solution, but it turns out that software is a better one.

Steps to Reproduce

Use a v0.2 VEXTREME to run the Test Cart rev.4 and set it to Deflection test. When the vectors turn off, you'll notice that there is this evil buzzing of bees.