NPN Transistor failure

Hello,
as per attached photo,
i got this simple schematic sketch.
i got GPS and Wireless module connected to arduino,
and i got another circuit for on-off latching switching,
this circuit out put feeds into the base of NPN transistor to turn the whole system,

the problem is when hc12 starts, it draws 200mA of current which causes short drop in voltage, this drop restart arduino each time !
i used 2n2222 npn transistor,
i tried changing it to Mosfet IRFZ34N and worked fine.
can somebody explain why NPN didnt work for me ?!

Hi,
Please post a circuit diagrams showing ALL connections including how you are powering the HC12.
A copy of your circuit, in CAD or a picture of a hand drawn circuit in jpg, png?

Also please post your code.
With the NPN, did you have a base resistor between the Arduino and the NPN base?

What model Arduino are you using?

Thanks.. Tom.. :smiley: :+1: :coffee: :australia:

The obvious solution would be to add a sizeable capacitor. Still, as in reply#2. A full schematic, including where you are getting the power from.

What is the value of the base resistor, and can that "latch IC" provide it
Required base current should be 5-10% of collector current for the transistor to switch properly,
so in this case at least 10mA.

Yep, mosfets only need gate voltage, not gate current.
Leo..