Op Amp Help

tom_pay said:

Hi Everyone,

I am trying to make a small amplifier for low-ish frequencies. 10 to 800 Hz.

I was planning to use a LM380 amplifier IC. However I have come across some problems.

1) What is the 'Bypass' pin? Do I need to put a capacitor on it?

2) What size AC coupling capacitor (on the input) should I use? Is there anything to govern this?

3) Can I put an AC input into the IC's input? The circuit only has single power supply (0 - 10v)

4) The IC has a fixed gain. I am only using the non-inverting input. What should I do with the inverting input? Do I let it float?

Thank you so much; in advanced. I'm sure that these questions are so simple and I'm just missing something. I'm so sorry.

Tom

Click to expand...

tom_pay said:

Hi Everyone,

I am trying to make a small amplifier for low-ish frequencies. 10 to 800 Hz.

I was planning to use a LM380 amplifier IC. However I have come across some problems.

1) What is the 'Bypass' pin? Do I need to put a capacitor on it?
Look at image1, it decoupling for the input stage, the value of the decoupling cap determines the power line noise freq/attenuation

2) What size AC coupling capacitor (on the input) should I use? Is there anything to govern this?
The input impedance is quoted a 150K, so if a input capacitor is used the required operating frequency range of the amp will set its value.

3) Can I put an AC input into the IC's input? The circuit only has single power supply (0 - 10v)
Yes, you require an input capacitor

4) The IC has a fixed gain. I am only using the non-inverting input. What should I do with the inverting input? Do I let it float?
The datasheet says it can be left disconnected


Thank you so much; in advanced. I'm sure that these questions are so simple and I'm just missing something. I'm so sorry.

Tom

Click to expand...