[sdiy] Mark Godfrey Pitch To FREQ woes (bad NTE?)

[Dan Snazelle]

I was very excited last night to try and build the mark godfrey pitch to voltage converter. it looked simple.

so i order an NTE995 which is supposed to be a direct replacment for the 14 pin lm2917m (it has a few NC pins and an extra opamp in and comp In, no BIG differences other than pin layout)

so i figured out the pin out

1=1
2=2
3=3
4=3 sort of
5=4
6=nc
7=nc

8=5
9=6
10=7
11==8 sort of
12=8 gnd
13=nc
14=nc


now i then followed marks schematic to a T. vcc on pin 9 (6) and gnd on 12 and maybe 11.

to make a long story short, i got it going, and uh-oh, the chip got hot. and nothing worked.

real hot.

i tried poring over the datasheets for both the 995 AND the lm2917 and could find nothing i needed to do differently except tie pins 11 and 12 together and pins 3 and 4 together.

heck, i even tried disconnecting it and powering it with a battery, still got hot.

is this just a case of a bum NTE chip ruining  my long awaited fun? or did i miss something fundamentally different between the two chips and in the process bust up the chip?

mouser calls it a direct replacement. (its really a 2917m)

what to do :(

aaron lanterman-btw, how does this circuit work? i have heard pretty well.

thanks all!

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