How many modules can Arduino UNO R3 support?

How many modules can Arduino UNO R3 support? I see this board have only 2 power pins (3.3 and 5V). If I would like to install more than 2 module. Can I deploy external power supply and connect only signal pin with analog or digital pin on UNO R3?

U cas use a small breadbord to make room for extra connections. There is also an the extra gnd and 5V on the 6pin header on your board.
Read the datasheet to see surrent considerations.
Its ok to use an additional 5V supply (with common gnd) to supply power to extarnal components.

knut_ny:
U cas use a small breadbord to make room for extra connections. There is also an the extra gnd and 5V on the 6pin header on your board.
Read the datasheet to see surrent considerations.
Its ok to use an additional 5V supply (with common gnd) to supply power to extarnal components.

I already connected UNO R3 and 2 channel relay module with Breadboard MB102+Power supply. I powered 2 channel relay module by power supply from MB102 and plug 2 signal pin from the relay module to UNO R3 directly. But It this module can't work . what wrong with them?

wichbu:
I already connected UNO R3 and 2 channel relay module with Breadboard MB102+Power supply. I powered 2 channel relay module by power supply from MB102 and plug 2 signal pin from the relay module to UNO R3 directly. But It this module can’t work . what wrong with them?

Sorry, but i left my crystal ball at work.

Which relay module ?

// Per.

wichbu:
I already connected UNO R3 and 2 channel relay module with Breadboard MB102+Power supply. I powered 2 channel relay module by power supply from MB102 and plug 2 signal pin from the relay module to UNO R3 directly. But It this module can't work . what wrong with them?

Maybe you forgot to connect GND of Arduino with GND of the breadboard , it will not work without grounds being connected together..
Electricity always needs a wire for the signal to flow to your circuit and a ground connection for the current to flow back . So it is a closed circuit.

cartoonist:

wichbu:
I already connected UNO R3 and 2 channel relay module with Breadboard MB102+Power supply. I powered 2 channel relay module by power supply from MB102 and plug 2 signal pin from the relay module to UNO R3 directly. But It this module can't work . what wrong with them?

Maybe you forgot to connect GND of Arduino with GND of the breadboard , it will not work without grounds being connected together..
Electricity always needs a wire for the signal to flow to your circuit and a ground connection for the current to flow back . So it is a closed circuit.

I plug vcc to + and gnd to - on mb102. I plug signal directly to digital pin on UNO r3 as well. Anything wrong with my config?