Hi dcb, "the man itself"
It's just that (with the datasheets in hand) it's not very clear what the zener is going to do when provided with a low current. Is it going to stay at 5.1 V? 3 V? or 0 V? An ideal zener would keep the 5.1 V, but what about a real one? It seems (to me) that the datasheet is "silent" about this point.
Well, if the experience tells that it works, it's OK, so no more to say...
I wasn't pretending to criticise or offend (of course!), I just wanted to understand the circuit.
By the way, great work!
Many thanks!
Quote:
Originally Posted by dcb
From my understanding, the zeners operate low on the "knee" at low currents, holding the voltage below 5.1 volts. It was tested and the injector'vss signals at the pin looked fine with an oscilloscope, as far as I can tell. The Zener is cheap, simple, and effective at forward and reverse voltage protection, and fairly common "normative?" practice.
If it aint broke why fix it? I tried a transistor circuit originally, didn't work the first time, and I want as many folks as possible to be able to get it working the first time. There's no reason an experienced person cannot embellish the interface or even the power supply or??? But my philosophy is simpler is better, especially with months of testing in many vehicles behind it and in lieu of a non-theoretical problem. |