Hi Andy,
"I am not so sure about that. Doing that would make the resistor between pins 11 and 12 unnecessary because it would be shorted out. I think they meant pin 12 to not be grounded in the Tach circuit. The use of the ground symbol inside the IC for pin 12 is misleading, I think. I like to think of it as on-chip VSS. Maybe I should use VEE since it is a bipolar circuit.
The detailed chip schematic in Figure 2 unfortunately uses the ground symbol everywhere, basically to indicate that they are all the same net ... which happens to be connected to ground in MOST but not all applications circuits. Like I say, it's misleading"
Yes, I agree. The ground symbols inside the IC were really meant to indicate an internal net that usually connects to an external ground.
"What exactly do you mean by the "new" LM2917 component?"
I meant the "modified version" of the Fig 2. schematic. I have block a symbol and working application circuit
I'd like another pair of eyes to review.
HT
