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lf351 pins to use?

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grendal

New Member
I was given this circuit and there is a lf351 ic chip that is shown as a triangle, I'm not sure how to use the chip or what's connected to where, I was never taught how to read this type of schematic. Anyone know what pins I should use? schematic is below.

:confused:
 

audioguru

Well-Known Member
Most Helpful Member
The LF351 opamp is old and is not made anymore. Similar opamps are available.
Ordinary opamps cannot drive low impedance headphones.

I usually go to datasheet sites but looking for LF351 in Google links to its datasheet that shows its pin numbers and a picture of its layout.
 

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grendal

New Member
I have the pin out but I guess what I'm trying to ask is what pins in the schematic are in use? The schematics I'm familiar with for ics are like this one.



it tells you wich pin goes where. In the schematic I'm having trouble with, there is 4 connections, but wich 4? It has 8 pins. pin 2 is the negative input, pin 3 is the positive input, pin 6 is output, pin 7 is positive voltage in, pin 4 is ground....so pins 1 and 5 is the balance and 8 is nc....so 1,5 and 8 float in this circuit?
 

Papabravo

Well-Known Member
The data sheet has all the information that you require. The pin numbers assigned to the output, the non-inverting input marked with a plus sign, and the non-inverting input marked with a minus sign are unabiguous. In much the same way that logic circuits are designed, modern CAD packages automatically hook the power supply pins to the appropriate voltages. It is a level of detail that is not needed once you look at the datasheet. So I guess what I am saying is look at the datasheet, then come back with more questions. Did I mention you need to look at the datasheet.
 

grendal

New Member
The LF351 opamp is old and is not made anymore. Similar opamps are available.
Ordinary opamps cannot drive low impedance headphones.

I usually go to datasheet sites but looking for LF351 in Google links to its datasheet that shows its pin numbers and a picture of its layout.
any advice for a modern cheap replacement to the lf351?
 

audioguru

Well-Known Member
Most Helpful Member
I think the circuit is supposed to give a hum when a nearby cell phone is ringing?
Then it uses the strong UHF or microwave signal transmitted to overload the input of the opamp.

I don't know if other similar opamps like the TL071 will overload the same.
The TL071 opamp has the same pin numbers.
 

grendal

New Member
it's supposed to produce a hum when in the presence of electro magnetic fields, humming louder and louder as you draw closer. Not sure if it works not yet built it, so I'd want something with a low overload...
 
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