im trying to explore the operation of the chip in zener regulated F>V circuit with 250mVpp @ 1khz,12V Vcc as prescirbed in the datasheet.my threshold levels are rated +-50mVpp so im quite sure that proper output Voh(8.3) and Vol(2.3) shoudl be produced at pin 2 or 3... my R1 is 100k C1 is 20nF and C2 is 1uF and a 10k transistor output(pin5)...
my problem is:
1.my reading at pin 2 is 580 mVdc max 2.my reading at pin 3 is 520mVdc max -> shouldnt it be equal to ic x R1 = 185uA x 100k = 18.5V where my ic or I2=I3 is rated to be about 185uA @ 25degree celsius as based from the datasheet graph 3.my reading at pin 5 is 420mVdc max -> the output voltage which says Vout = 66Hz/volt is nowhere to be attained. changing the input frequency from my function gen. doesnt alter the Vout in anyway...why? 4.my application is in metal detedector. i have a lc tuned oscillator and i want to use the frequency change as my indicator of metal presence as opposed to "mixing"...or dou you have any other way to do this? meaning a simple switch in which when a certain threshold frequency is attained, it outputs a certain voltge level?thanks! help please!
datasheet is here: