50Hz/ 60Hz noise filter

[humhum]

Please help my
ı need 50/60hz noise or notch filter for ZAHORİ (ivconic) device.

[Esteban]

This is a good filter. Other figure the same filter with pins of the IC.

Regards

Esteban

[ivconic]

Yes, i agree with Esteban.
Well done Esteban!

[Unregistered]

i need shematic transmit tm808,

tm808

[ivconic]

Unregistered!? Why dont you register and use search option, instead poping up here, in wrong topic and spoiling subject???
Ok...here is answer to your question...damn!

https://www.geotech1.com/thuntings/showthread.php?t=12324&highlight=tm808

Happy now?

[Aziz]

For small signals, it might be usefull to reduce the 1 M resistor and increase the capacitor instead. 1 M resistors have a big thermal noise.

For the cut-off frequency take the following formula:
fc=1 / (2*PI*R*C) [Hz]

Taking R=1M and C=3.3nF:
fc=1 / (2*PI * 1.0e+6 * 3.3e-9) = 48.23 Hz


Aziz

[ivconic]

Aziz you got the point. However, sampling frequency at Zahori is adjustable in wide range, so...it should be hard task to establish proper filter to cover all the range there..hmmm? Dont have a clue?
So as i noticed, there is one "sweet" spot at 2M2 pot. where Zahori starts to work very clean.
Never tried to examine that more...sheesh! Lazy me!

[Esteban]

For small signals, it might be usefull to reduce the 1 M resistor and increase the capacitor instead. 1 M resistors have a big thermal noise.

For the cut-off frequency take the following formula:
fc=1 / (2*PI*R*C) [Hz]

Taking R=1M and C=3.3nF:
fc=1 / (2*PI * 1.0e+6 * 3.3e-9) = 48.23 Hz


Aziz

Yes, but with 1% film resistor noise will be reduce.

Regards

Esteban

[Aziz]

Hi all,

yes, 1% metal film resistors have lower noise characteristics. Ban all your 5% resistors from your metal detector!

See additional (thermal noise):
http://en.wikipedia.org/wiki/Thermal_noise

The lower the resistance, the lower the noise!

Aziz

[Esteban]

Hi all,

yes, 1% metal film resistors have lower noise characteristics. Ban all your 5% resistors from your metal detector!

See additional (thermal noise):
http://en.wikipedia.org/wiki/Thermal_noise

The lower the resistance, the lower the noise!

Aziz

I have metal detector circuit all 1% resistors! (except 2).

Regards

Esteban

[humhum]

Esteban Thenks very much for filter .

[Max]

I have metal detector circuit all 1% resistors! (except 2).

Regards

Esteban

Let me guess ... you added the other 2... 1/2w carbon 20% tol kind!

Reminds me to something else...

No... no... I know you don't make "such" enhancements... just you keep them reserved for pistols...

Kind regards,
Max

[Aziz]

Let me guess ... you added the other 2... 1/2w carbon 20% tol kind!

Reminds me to something else...

No... no... I know you don't make "such" enhancements... just you keep them reserved for pistols...

Kind regards,
Max

For LRL detectors, you need some noisy resistors. The detection is dependent of the coincidence (noise).

Ok, I am a bad guy!

Aziz

[Esteban]

Let me guess ... you added the other 2... 1/2w carbon 20% tol kind!

Reminds me to something else...

No... no... I know you don't make "such" enhancements... just you keep them reserved for pistols...

Kind regards,
Max

Hi
I post list of materials of Wilson VLF 710, almost all are 1% and some very rare values. Is in reference to this detector the theme of 1% resistors in detectors. You can see very clear images in the zip file below.

And see the list here:

https://www.geotech1.com/thuntings/showthread.php?t=14255&page=4

P.S. I don't use 1% in pistol, except resistor in emitter of oscillator transistor... sometimes

Regards

Esteban

[Esteban]

For LRL detectors, you need some noisy resistors. The detection is dependent of the coincidence (noise).

Ok, I am a bad guy!

Aziz

Don't worry. A fraction of noise can be good if you consider open base system.

Regards