help with amplifier circuit

mshh said:

the transistor is just a switch here so i think that npn and pnp should do the job. i want to use npn as it is available in my hand now.also it will be fine to know the difference . i did your circuit in proteus using opamp lm358 and bc557

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i tried lm324 and your transistor 2n3906 and it give logical correct results . i got this result when i replaced lm358 with lm324 , what is the reason for that?

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crutschow said:

Yes both NPNs and PNPs can be used as a switch but all the pin polarities are opposite. If you can figure out how to do that with your circuit requirements, have at it.

The LM324 and LM358 are basically the same circuit and should have the same simulation model so don't understand why there's a difference in your simulations.

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mshh said:

thank you for your help it gives now the same result but the maximum output is 4 volt when the supply voltage is 5 volt however the maximum should be 5 volt

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