Microcircuit AD8422 is very noisy.

In addition, I put the circuit in a shielded iron case, and soldered the middle power point to the iron, the situation has not changed, the noise is still 800 millivolts.

Some recommended - put the positive and negative power supply tracks on opposite sides of the board, but on top of each other for magnetic coupling.

Should I run the power supply tracks on shielded wire?

Please help me to make a circuit with low noise, point out my mistakes.

Hi slava1 ,

Good day. Can you share the schematic so we can visualize your circuit further? Several factors could contribute to the measured noise, such as the supply noise and the resistor noise. I think what you are measuring here is the 0.1 to 10 Hz noise, which is similar to Figure 42.

Can you also provide the measurement of the output of the first AD8422? Thank you.

Regards,
Gilbeys

Привет,  ГЛАДИОН.

Схема питается от четырех аккумуляторов 18650 от биполярного источника питания со средней точкой.

На первом видео два чипа работают с усилением 100000x, увидел шум от пика до пика 627 милливольт. Иногда бывают большие игольчатые всплески, это шум от телефона, а также каждые 14 секунд вращается локатор, который тоже дает всплески.

У меня есть осциллограф с чувствительностью 10 милливольт, но иногда он показывает шум в 5 - 6 милливольт. А также всплески от работы телефона, когда я не снимал видео, их не было.

Третье видео, я так же снимаю работу первого усилителя с усилением 1000 крат, но держу камеру ближе, также вижу всплески от работы телефона, и показываю снятую вторую микросхему ad8422.

четвертое видео снова усилено в 100 000 раз.

Показываю, что чипы ad8422 я купил на digikey.

Показано, как выглядит микросхема ad8422.

I didn't understand from your graph what the noise should be at 100000x gain, so I don't know what to aim for.

Hi slava1 ,

Please share the schematic so that we can analyze it further. Thank you.

Regards,
Gilbeys

Hi GLADION, here is the schematic, all incoming resistors are unsoldered, only the 1000x gain resistor is soldered on

Hi slava1 ,

Do you have the circuit diagram for this instead of the actual? I'm planning to run it on LTSpice to simulate it and I need the circuit to figure it out.

Something similar to figure 64 would help a lot. Thank you.

Regards,
Gilbeys

Привет,  ГЛАДИОН.

Так схема в первом посте или она у вас не работает?

вот диаграмма

I tried measuring the noise on the first chip, where the gain is 1000 times, and the noise was 5 - 6 millivolts.

Привет,  ГЛАДИОН.  I'm writing because all the files with videos and pictures that I uploaded appeared.

It is possible to connect as I have connected according to the diagram, or I have a mistake somewhere?

Hi GLADION

I drew the diagram more nicely

Could you please simulate the circuit for noise?

Hi GLADION

The board is not made neatly, it is a test sample, I did not take everything into account, on this re-soldering more than once, supplemented, the circuit itself later I will do a better quality, and shielding.

Hi GLADION

I made a mistake when I drew the circuit, resistor R3 is connected to ground. I corrected the diagram and removed the wrong drawings.