HP41C with Rp Pico attached

[Tinue]

(12-02-2023 11:53 AM)blackjetrock Wrote:  The 125 can shift down as it runs off the 3V3 and is tolerant to 5V, I don't think you can shift up from 3V3 with that device? Or are you running off 5V and putting a 3V3 signal in?

I have used the 125 to drive an LED strip, which needs 5V input, from a Raspberry Pi. VCC of the 125 was 5V, and this was then also the output voltage. I later found out that the LED strip is happy with the 3.3V as well, and dropped the 125.

For now, I am using a simple circuit with two resistors and a transistor, which works fine. But it really looks like this is not necessary, and I can simply connect the input of the C4103A directly to the Pico. I already checked the other way round: The C4103A seems to be fine with the 3.3V input from the Pico, and produces a clean signal.

Thanks again, and sorry for misusing this thread. I'll shut up now ;-)