what is the functionality of following circuit? It's a LM324 opamp and a sin or ramp signal get into it's inverting input and non-inverting input grounded. It's power is 12 and -12 and output of op amp with a 10k resistor connected to transistor (2n6660) ?
Assuming this is the whole circuit, we can conclude from the lack of feedback that it is used as a comparator.
The input is connected to the negative input, with ground on the positive. If the input is positive, the output will be as negative as the OP-amp can make it. If the input is negative, the OP-amp output will be as positive as it can make it.
This signal turns an transistor on or off, but we can't say much more about that.
It is possible that the output is connected with a larger feedback loop back to the input, in which case this could have a different function. Without the whole circuit it's hard to tell.