- #1
likephysics
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I am trying to drive a NPN transistor with a LM324 op amp. The darn transistor does not turn on when driven by an op amp.
This is basically a current limit circuit. Instead of using a large value sense resistor, I used a small resistor(0.1 ohm) and used an op amp to sense and increase the voltage to turn ON the NPN(2N2222) transistor when the current limit is reached.
The op amp I am using is LM324. From the datasheet, it's more than capable of souring enough output current to turn ON the 2222. Not sure why it's not working.
pdf attached.
This is basically a current limit circuit. Instead of using a large value sense resistor, I used a small resistor(0.1 ohm) and used an op amp to sense and increase the voltage to turn ON the NPN(2N2222) transistor when the current limit is reached.
The op amp I am using is LM324. From the datasheet, it's more than capable of souring enough output current to turn ON the 2222. Not sure why it's not working.
pdf attached.