…but BD140 it is a pnp transistor, and in circuit apears as npn.
Even more, as a pnp it will always allow current to led, no matter what trimmer R6.(R6 WILL BE USELESS BECAUSE Q1 WILL ACT AS A DIODE) I’m sure you could use BD135 which is a npn, as the BC547. Ferther more,almost all the current from Q1 passes throu Q2 (BC547) so i think it is an idea to use BC547 as Q1 too.
AGAIN THANKS FOR YOUR IMPRESIVE WEBSITE – KEEP UP THE GOOD WORK!!!
GREETINGS FROM GREECE!!!