Can u use a tip 50 instead of tip 102 or 122?
NO - A TIP50 is a standard (single) transistor and both TIP102 and TIP122 are Darlington transistors (two transistors built into the one case).
The gain of a TIP50 won't be anywhere bear enough to replace a 102 or 122.
Ok thanks, just saw 25 for $5 and thought it would be a bargain if I could
