Hi Guys,
I've been looking at a few data sheets, and it seems to me that it's possible to use switching FETs for amplifier output stages:
1: most FETs are designed for switching anyway
2: Switching FETs are much cheaper; I can get MTP3055 for around AUD 2 each, got some IRF740 free out of a junked power supply (so why did I pay AUD 18 each for a fancy Hitachi pair???)
3: If it's for a guitar amp, most Guitar hero wannabes are going using distortion anyway, so the amp doesn't need to be audiophool clean (an audiophool would use BJTs anyway)
Looking at the data sheets, it seems that the switching fets have higher cutoff voltages than the Hitachis, but surely this is just a matter of having the appropriate bias voltage? (I'm looking at the transfer charachteristics graph)
(I'm assuming also that the devices have acceptible Ciss & Rds)
Shoot me down in flames or enlighten me if you think I'm barking up the wrong kettle of fish. I'm going to try an output stage using the switching FETs first, then try it with the Hitachis (too chicken to risk $36).
Cheers, Pete McK
I've been looking at a few data sheets, and it seems to me that it's possible to use switching FETs for amplifier output stages:
1: most FETs are designed for switching anyway
2: Switching FETs are much cheaper; I can get MTP3055 for around AUD 2 each, got some IRF740 free out of a junked power supply (so why did I pay AUD 18 each for a fancy Hitachi pair???)
3: If it's for a guitar amp, most Guitar hero wannabes are going using distortion anyway, so the amp doesn't need to be audiophool clean (an audiophool would use BJTs anyway)
Looking at the data sheets, it seems that the switching fets have higher cutoff voltages than the Hitachis, but surely this is just a matter of having the appropriate bias voltage? (I'm looking at the transfer charachteristics graph)
(I'm assuming also that the devices have acceptible Ciss & Rds)
Shoot me down in flames or enlighten me if you think I'm barking up the wrong kettle of fish. I'm going to try an output stage using the switching FETs first, then try it with the Hitachis (too chicken to risk $36).
Cheers, Pete McK