Simple Switching Circuit

Thread Starter


Joined Jul 19, 2016
I have that model for a circuit used for IGBTs firing

I want to energize A then B from microcontroller in a frequency about 50kHZ. with about 10 mA
I want microcontroller pin not to be loaded with more than 1 mA.
firstly I have intended to use "transistor as a switch" but I can not use it with common collector because the ground is common, so I have use it as common emmtier. but the problem is the output current is not greater than 3mA even if using Vcc for transistor with 12V and higher current gain models (2n2222, bc247...)
Also I can not use optocoupler as circuit frequency is high (about 50kHZ)
I am searching for a solution. Thanks in advance



Joined Nov 30, 2010
what if there is any problems with R1 and loose connection to Vcc, can there is any unexpected operation of PNP transistor??
Lacking R1 will allow Q2 to be enabled more easily if there is any leakage through Q1.
Lacking Vcc will stop Q2 from activating.
If you have these problems, repair them.
Anyone who posts a schematic expects you to assemble it correctly. If you leave parts badly connected, it is nobody's fault but your own.