I need transistor T221 on a Motronic 1.3. I cannot get info on which type it is......Don? It is up against a relay on the board so even if you have an ECU, you would be hard pressed on seeing the part no.
Who could forget Sidney Darlington...Not sure if T221 is the High Voltage Ignition Coil Driver, in that case I read it can be a SGS/Thompson BU931P NPN Power Darlington.
https://ethw.org/Sidney_DarlingtonAlways a tinkerer, Darlington in the 1950s spent a weekend at home playing with a new gadget, the transistor. Trying to get more gain from an amplifier the size of a kernel of corn, he found a way to combine two or more transistors in one chip, an idea that became the Darlington type of Compound Chip and pointed the way toward integrated circuits. He patented the idea and lived to see the Darlington chip become required study for electrical engineering students everywhere. Darlington also made advances in radar, inventing the pulse compression ("chirp") radar in 1947. This approach, using several frequencies to lower the demands for high peak power, made possible the antiballistic missile defense system.
I purchased the ecu on ebay, but it is completely different than the s38 one I have. I was hoping for the main realy circuit to be the same so I can identify the Trans that I need. Unfortunately the one in question is unreadable and although it is a t0-92 design, I do not know which one of the 4 or 5 that BMW seems to use in the ECU. It is possibly a 548C or 558B. Both are cheap and easy to get, but not sure which one. I do know that it is in the main relay section of the board, but thats it.
Update...found a small chip of plastic on the shop floor and it was the piece that had the first 2 digits that were needed to figure out exactly which trans was needed. Thanks for the help with this all.