What the different between those AMP

Hi guys

What the different between
LF412ACN/NOPB and LF412CN/NOPB ?

Shown in the link below

**broken link removed**

I want to get a LF412 test on breadboard

Hope you guys can help me
Thanks

chenjk09 said:

Hi guys

What the different between
LF412ACN/NOPB and LF412CN/NOPB ?

Shown in the link below

**broken link removed**

I want to get a LF412 test on breadboard

Hope you guys can help me
Thanks

Click to expand...

hi,
looking at the d/s, the LF412A has a 'better' specification than the LF412.
Lower offset, higher working voltage and the d/s says the LF412A is 100% tested for performance compared to the LF412 which is only batch sampled.

The section depends on the circuit you are building, what is it.?

ericgibbs said:

hi,
looking at the d/s, the LF412A has a 'better' specification than the LF412.
Lower offset, higher working voltage and the d/s says the LF412A is 100% tested for performance compared to the LF412 which is only batch sampled.

The section depends on the circuit you are building, what is it.?

Click to expand...

Hi,

Thanks for your reply..
I want to build an ECG Front End
base on the web site shown below
**broken link removed**
so LF412ACN/NOPB has a 'Better' specification

Check with you base on the web site it has LF412A/LF412B
I only need 1 LF412ACN for LF412A and LF412B correct?
So total i only need 2 LF412ACN/NOPB correct?
base on data shown below
https://www.electro-tech-online.com/custompdfs/2012/01/lf412-n.pdf
It has base on page 2
I'm correct???

An Instrumentation amplifier IC is used for the front end of an ECG circuit because its amplifiers and circuit resistors are extremely well-matched for very good common-mode interference rejection. Here is an example using an AD620A instrumentation amplifier IC:

chenjk09 said:

Hi,

Thanks for your reply..
I want to build an ECG Front End

Click to expand...

hi,
Use an Instrumentation amplifier for the ECG front end.

You need a high CMMR for an ECG in order to cancel out unwanted signals.

audioguru said:

An Instrumentation amplifier IC is used for the front end of an ECG circuit because its amplifiers and circuit resistors are extremely well-matched for very good common-mode interference rejection. Here is an example using an AD620A instrumentation amplifier IC:

Click to expand...

Hi,

Base on the link shown below it also use AD620
**broken link removed**

If base on your circuit what the value for C1, capacitor value, High pass filter circuit and built patient/circuit protection/isolation ?

ericgibbs said:

hi,
Use an Instrumentation amplifier for the ECG front end.

You need a high CMMR for an ECG in order to cancel out unwanted signals.

Click to expand...

Hi

Base on the web site shown below it has Instrumentation amplifier
**broken link removed**

chenjk09 said:

If base on your circuit what the value for C1, capacitor value?

Click to expand...

It is a lowpass shelving filter. Calculate the capacitor value for whatever cutoff frequency you want.

High pass filter circuit?

Click to expand...

Make it yourself with whatever parts you want to use.

built patient/circuit protection/isolation?

Click to expand...

Use a battery to power the circuit so that it has isolation from the mains to avoid electrocuting the patient if something shorts.

Ad620

audioguru said:

It is a lowpass shelving filter. Calculate the capacitor value for whatever cutoff frequency you want.


Make it yourself with whatever parts you want to use.


Use a battery to power the circuit so that it has isolation from the mains to avoid electrocuting the patient if something shorts.

Click to expand...

Hi,

I want to build an ECG Front End system.

Base on Data Sheet of AD620 Figure 36.

I have highlighted in red square (Q1 – Q5) those items that I need clarifications.

For
Q1 Using battery it will solve ‘PATIENT/CIRCUIT PROTECTION/ISOLATION’
Q2 How to calculation for C1
Q3 ??
Q4 ??
Q5 ??

Appreciate if you can advise.

Thanks

I answered most of your questions but I won't design the circuit for you.
Q1- Some ECG circuits use a 390k high voltage resistor to isolate each connection to the patient. The schematic shows that the circuit is powered by two 3V batteries and the highpass filter input coupling capacitor isolates the patient from electricity in the computer.
Q2- C1 is calculated with R1 and R4 to form a lowpass filter.
Q3- The batteries help isolate the patient from electricity.
Q4- The highpass filter is simply calculated as a coupling capacitor that feeds a resistance.
Q5- An opamp uses only two resistors to set its gain. A gain of only 143 times is easy.