My question is very simple, i dont have much experience with electronics, and i am developing a project where i will use some operational amplifiers (TL081) and 1 instrumentation amplifier (INA118).

I'll need the TL081 to build voltage followers, and a Voltage-Controlled Current Source (Mirrored Modified Howland):

enter image description here

Source: http://iopscience.iop.org/article/10.1088/1742-6596/407/1/012030/pdf

The INA118 amplifies the input voltage from the two electrodes placed on the body. Similar to this project.

In these cases, do I need to use a DC supply voltage in my ICs TL081 and INA118? I was looking at projects that use applications similar to mine, and I did not see any comments about it.


  • 2
    \$\begingroup\$ The opamp and the instrumentation amp will both need a DC powersupply. Use batteries since you are attaching this to a human body. Amplifiers ALL need a powersupply to operate. Given your lack of basic knowledge, please reconsider carrying out your project - you may hurt yourself or someone else when connecting to people. \$\endgroup\$
    – JRE
    Commented Dec 19, 2016 at 21:41

1 Answer 1


Yes, you will need to provide power supplies to any op-amp or in-amp in your circuit if you want them to act like op-amps and in-amps.

You can see in the datasheet (INA118 shown) this is specified in the "recommended operating conditions" table: enter image description here

Most of the other specifications in the datasheet are only valid if you are operating the chip according to the recommended operating conditions.


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