strange noise preamp 2 stage

[Wahyu]

Hi All, i have problem strange noise at 2 stage preamp
at pin 1 normal signal, but at pin 7 noise appears,

i use IC LM4562

Schematic;


Pin 1;



Pin 7;


what problem i have, need help for this problem,

Thank,

Wahyu.

[kt315]

if it is bara you must open thread in bara subforum. if idx - in idx. WHAT is IT?

[Wahyu]

hello kt315

thank for reply, i will find at baracuda,
i just new design for PI

Wahyu.

[eclipse]

looks like the preamp from Td3x from Dooley, do you trust your oscilloscope readings?

[Wahyu]

yea this from TD3X i just try to modified for next stage, integrator, etc

mmmmm,,, not realy trust, i use Hantek 20Mhz usb pc, maybe noise from my device.

Thank for reply eclipse.

Wahyu.

[homefire]

I think your just seeing the Noise Amplified by the two Gain Blocks.

HF

[DOOLEY]

AGREED,
looks like noise amplified.

also looks like coil under damped, bit of a dip there after the spike.

notice there is also noise BEFORE TX on time.

could be oscilloscope,

are shielded cables being used on coil and scope ??

[green]

Looks like your scope probe is x10 and scope common is on -supply instead of +4volts(common). Not familiar with your scope so maybe I'm looking at it wrong. Assuming the not labeled resistor on pin 6 is 1k the noise on pin 7 would be 34x pin 1.

[kt315]

AGREED,
looks like noise amplified.

also looks like coil under damped, bit of a dip there after the spike.

notice there is also noise BEFORE TX on time.

could be oscilloscope,

are shielded cables being used on coil and scope ??

there is long story told by Eric Foster (long text) how he did find up the source of the noise in his detector.
he found that! it was modern energy saver lamps in his room. LOL!
simply guys you do not wish to read Technology Forum where Eric is moderator and this is your problem.

[DOOLEY]

I AGREE KT315,

i was so annoyed with my over bench fluorescent lights giving of lots of noise i
upgraded to modern day LED strip lighting !!!

little did i know that the power supply for the the new lights would ALSO give of lots
of EMI !!!
LOL.

there still better though than the old fluorescent lights.

[kt315]

http://www.findmall.com/search.php?3...atch_threads=0

[6666]

http://www.findmall.com/search.php?3...atch_threads=0

The link does not work for me.

[kt315]

The link does not work for me.

because you have to wait a time, just as it is SEARCH running link. wait and take patience.

[6666]

because you have to wait a time, just as it is SEARCH running link. wait and take patience.

Ok I waited 2 minutes then got result.

[Wahyu]

Hello All, thank for advice, solve my probe scope x10 switch to x1, noise disapear

Wahyu.