how do i fully open a bjt transistor and how to calculate the saturate?

if i fully open the bc337 base so it start act like a switch. so what is the value that should be looking for.
I am trying to know the current voltage from the datasheet, which i can give to supply.

Rule of thumb, collector current max 10x base current.

In most datasheets the gain is not mentioned for DC.

Haigler1M:
if i fully open the bc337 base so it start act like a switch. so what is the value that should be looking for.
I am trying to know the current voltage from the datasheet, which i can give to supply.

In English for electrical circuits "open" means off, not on. A water tap is on (flow) if opened, but an open circuit
is broken (no flow). So always use 'on' and 'off' for electronics to avoid confusion.

5% to 10% of the collector current is needed to fully saturate a BJT, which gives the most efficient
switching (least heat wasted in device). The dc current gain is nothing to do with saturation, that only
applies to the active/linear region of operation, where the collector is more positive than the base (for
an NPN).