I am trying to understand why connecting, say, an Arduino digital pin 4 to a 2N4401
pin 2 as well as 5V
PSU to 2N4401
pin 1 and Arduino VCC
to 2N4401
pin 3, won't keep power.
When shorting pin 1 and pin 3 on the 2N4401
the MCU is powered on and in-software pin 4 is set to pinMode
OUTPUT
and HIGH
which should allow the 2N4401
to let power flow to the MCU for as long as power is available even when the short circuit between 2N4401
pin 1 and 3 is cut.
Instead what happens when the short between pin 1 and 3 is cut, the MCU is turned off instantly.
It's as if the transistor isn't reacting to the pin 4 MCU signal at all.
Could anyone explain why this is happening?
I'm sure I lack a lot of knowledge here and I want to know how I could utilize a 2N4401
to make a SW shutdown system.
Why 2N4401
? Why not a MOSFET?
MOSFET's circuits that do SW shutdown are available, but no transistor base SW shutdown circuits are to be found anywhere, and the 2N4401
is all that I have right now.
Update
void setup(){
pinMode(4, OUTPUT);
}
void loop(){
digitalWrite(4, HIGH);
delay(3000);
digitalWrite(4, LOW);
}
loop
function - you probably need anotherdelay
after thedigitalWrite(4, LOW)
otherwise it will immediately writeHIGH
again on the next loop - so you won't really see the effect of theLOW
as it will be too short. A proper schematic is necessary to see which way you have the transistor connected.HIGH
tells the transistor to allow electricity to flow to the board, right? So my question is why would a delay afterLOW
be needed whenLOW
would turn it off, which is what I want?