Help - Partitor or zener

http://everycircuit.com/circuit/5243027172622336

It depends on what you'll be using it for. What's the input resistance supposed to be? 1Mohm? Notice how one is more sensitive to the resistance of the load?

@crake it's a nodeMCU, so I suppose high impedance pins. It's a digital signal from 5V to 3.3V (Ultrasonic sensor)

current consumtion? Constant or periodic active, importante for the current to know if its constant a simple resistor might do, if not a zener might be needed or more? Without this info @crake and i cant help you

Would you mind posting a link of the sensor? For digital stuff I'd probably just buy a level shifter. Wherever you got this from probably sells level shifters too.

Also, you say you're using arduino. Most are 5V while some are 3.3V. What arduino are you using?

i can only think of arduino UNO does use 5V

right, a detailed type nr to lookup a specification for your ultasonic sensor, would be nice. He could help you to read and can then recommend what you can do best.

I've used UNO, MEGA and Nano and all were 5V. My DUE is 3.3V. Last I checked Arduino was offering more 3.3V options but not sure how many

I think it needs a clarification, arduino is a big big hugh field, nobody can overview. If you say arduino you mean an environment, not a chip. Sorry, if i said arduino, i mean atmel, i started being unprecise. And the only old enough chip from atmel for an arduino environment is atmega for UNO. As far i remember while writing this commment, only this only chip uses 5V. All others from atmel are newer and work with lower voltages 3.3V or 3V. Due is SAM and an ARM core this chip is build in license of ARM and can come from any manufactur, sure it is not for 5V it below. UNO is atmel old atmega chip 5V, MEGA atmel and which chip also old atmega, no must be something newer right? Mostlikely below 5V. Nano, chip idk, but also a newer one then atmega from UNO. The boards around might have a 5V pin sure for compatibility reasons. But if the chip needs that i dont think so, only UNO is powered atmega chip with +5V ! with 3V it does not work.

Yep, I know what you mean now. I haven’t looked at the datasheet for the atmega2560 in a while but I’m pretty sure it can operate as low as 1.8V. Never pushed it that low though. Now days I prefer using the pic18f14k22 for quick and small stuff. Don’t really use arduino much anymore. Maybe boggiano could check his circuit and let us know what he is using lol

we speculate and speculate ..... blah blah.... and he needs HELP, but is silent. I love that. Actually @crake, im afraid we can forget that topic, for my taste hes to slow or lazy or ignorant or idk.... unbookmarked

The ultrasonic sensor is the classic one (HC-SR04) and its output it is 5V. The signal must be read from a NodeMCU and I know it wants 3.3V. I suppose inout pins at high impedence (so I used 1MOhm). The board will be supply from the socket wall and I can get 5V from the board to supply the sensor. Make sense ? I know about level converters but I was thinking about partitor vs zener in a academic way! Just for fun! :) Thanks