Hi, I bought 3 bi-color LED bargraphs. I have hooked it up to a raspberry pi, using MCP23017 and using 470ohm resistors along with 3 PNPs. The circuits and program seems to work fine. However, some leds are fully lit and others are dim. When I swap out the bargraph LED, the same problems but different leds on the bargraph are dimmer or brighter. If I, replug the bargraph, same pattern of dim and bright. But different patterns with different bargraphs. Everything else is the same, but different results with different bargraphs.
So I am thinking are they defective? But I seem to be able to get those dimmly lit LED straight to battery of 3v.
any suggestions on if the bargraphs are defective or something wrong with my circuit components.?