Does Rotary encoders work WITHOUT being connected to Vcc?

[K-rnivoro]

I bought some rotary encoders soldered to a small PCB who have a Pin connected to Vcc.
On the PCB are two 10K resistors connecting Vcc to CLK and DAT respectively. I guess they are pull-up resistors.
According the diagram at the Control Surface page, there is no need for Vcc connection of the encoder, however if I disconnect the Vcc (actually 3.3V from the Pi) the encoder stops working.
I'd prefer to buy "non PCB soldered encoders" because are smaller, but I'm not sure if it is a particular thing of this PCB soldered encoders, or every encoder have to be connected to Vcc through resistors.

[opjose]

AFAIK the encoders on the boards use a voltage divider requiring the VCC to produce the pulses.

The encoders by themselves don't require VCC.

I haven't tried this on a PI, but I recently built a Flight Sim panel using a USB interface board.

I ran across the same issue using the encoders with boards, and resorted to using the encoders without boards for the USB interface.
The interface only required ground and signal connections in each direction. If I only connected ground and one side of the encoder I would see pulses at the connected pin.

Note that like the PI the USB board I was using pulled the input pin high through resistors for the "off" state.

[K-rnivoro]

So, the VCC is needed. Then the diagram of the Control Surface page can be misleading because it shows only the Encoder pins, like Vcc (and the resistors) wouldn't be mandatory.

[opjose]

The VCC is not needed if you are using a board less rotary encoder. The diagram is ok.

The encoder only makes or breaks connections as it is turned. The CLK signal is misleading because it typically is not an actual clock, but rather the other side of the switched inputs... in other words CLK is one direction while DAT is the other...

See: https://thecustomizewindows.com/2017/07/rotary-encoder-dummies-arduino-raspberry-pi/

Note OUT-A and OUT-B those are momentarily grounded as the encoder is turned.

The board versions use a voltage divider which is why the VCC line is needed for those.

[K-rnivoro]

Thanks for enligthenment.