It's easier to buy transistors of the desired A/B/C range and layout for the minimum gain. In practice it's sufficient to have the highest gain class in stock. A proper layout for hfe=50 will work with 250 as well.
It's easier to buy transistors of the desired A/B/C range and layout for the minimum gain. In practice it's sufficient to have the highest gain class in stock. A proper layout for hfe=50 will work with 250 as well.