I've always used the plastic package transistors for low current stuff. And I was under the assumption that the metal case version, such as the TO-18, allowed more collector current...because the metal case could radiate heat better or have a heat sink clamped to it.
But when I look up an example that I might use - 2N2907A - I see that the plastic TO-92 version has a higher collector current spec than the TO-18 metal case version. This seems odd to me.
Okay, so maybe the metal case provides shielding. But unless the metal case is grounded, does it really provide any shielding? Doesn't it need to be connected to ground in order to shunt the interference somewhere?
But when I look up an example that I might use - 2N2907A - I see that the plastic TO-92 version has a higher collector current spec than the TO-18 metal case version. This seems odd to me.
Okay, so maybe the metal case provides shielding. But unless the metal case is grounded, does it really provide any shielding? Doesn't it need to be connected to ground in order to shunt the interference somewhere?