#zeners:
'12V' 'D3'
'15V' 'D3'
#diodes:
'BAV21' 'D3'
#Tranzorbs:
'P6KE33A' 'D5'
# transistors:
'BC237' 'TO92'
'BC307' 'TO92'
'2N4401' 'TO92-INVERT'
'2N4403' 'TO92-INVERT'