Hi
I should develop a connection cable from a PC to a car control unit

can someone tell me if I can replace some components with others I already have?

in particular:
the transistors bc546 with c945c
the diode 1N4004 with 1N4007

I attach the outline
thank you

 

Hi
I should develop a connection cable from a PC to a car control unit

What control unit? What are you trying to control? What do you think you can change in the unit? Most cars have more than one "control unit". And I'm not sure if they can be changed, at least without the correct manufacturers protocol system.

 

a friend of mine asked me if I can create a cable from a PC to a methane plant control unit "e @ gas",

I already have some components, and I asked if they are compatible with those in the scheme

 

They will probably work. The transistors are not critical and the 1N4007 is just a higher voltage version of the iN4004.
Build it and connect its "engine rpm" to "lamda signal", power it from 12V, start up a serial terminal on your PC and see if what you type appears on the screen. make sure "local echo" is turned off on your terminal program otherwise you may think it is working when it is not.
This is a "loop back" test, sending the transmit data back to the receive data.
Note. Do not connect it to the car for this test, just to itself.

But just know that fiddling with a car computer can cause damage.