op amp

The op amps on this circuit look correct but where the offsets usually are its labeled v+ and v- which do i use. i am using the 8 pin tlo81cp op amps ...thanksView attachment pirdetect.pdf

jboulton said:

The op amps on this circuit look correct but where the offsets usually are its labeled v+ and v- which do i use. i am using the 8 pin tlo81cp op amps ...thanksView attachment 24366

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hi,

When you say 'offset' do you mean the supply pins.?

I dont see any offsets.?

where the supply pins are labels on the schematic in reference to the op amps in all schematics that Ive seen referred too the offset n1 and n2 but in this schematic the side branches of the op amp symbols are labeled v+ and v- is that in reference to the supply pins or just the inputs needed to go to the offsetsView attachment op amp symbol.doc...thanx again

Connect all power supply pins.

The circuit diagram uses two dual op-amp ICs so only connects up two power supplies.

Why don't you use the TL084 which has four op-amps in the same package?

Offset trimming isn't required so using four TL081s is a waste of money.

jboulton said:

where the supply pins are labels on the schematic in reference to the op amps in all schematics that Ive seen referred too the offset n1 and n2 but in this schematic the side branches of the op amp symbols are labeled v+ and v- is that in reference to the supply pins or just the inputs needed to go to the offsetsView attachment 24367...thanx again

Click to expand...

hi,
The TS27L2C is a dual CMOS precision OPA.
Pin 8 goes to the +9V and pin 4 goes to the 0V line.

OK.?

It also has a quad version, the TS27L4C; I recommend using it over the dual one.
https://www.electro-tech-online.com/custompdfs/2008/12/2305.pdf

jboulton said:

The op amps on this circuit look correct but where the offsets usually are its labeled v+ and v- which do i use. i am using the 8 pin tlo81cp op amps

Click to expand...

v+ is the positive power supply pin 8 of the dual opamp and pin 4 is the negative power supply pin 4. The dual opamp is in an 8 pins package and does not have input offset adjust pins.

Since you are using single opamps then look on its datasheet to see which pin does what.

The TL081 is completely different from the opamps in the circuit and might not work.
The original opamps have inputs that work perfectly at 0V. The TL081 has inputs that have the phase-inversion problem when their voltage is within 3V of 0V.
The original opamps have outputs that go to 0V. The TL081 has an output that does not go to 0V but stops at +1.2V.