Doubt regarding Noise in the system

[rama1001]

Hi,
I am new to circuit design. Although, I am designing CSA&SA(charge sensitive @ shaping amplifier) for our detector system to detect the radon gas emission. We soldered every thing and we observe the output that is bit noisy.
I learned some concepts in my course about groundong shield to reduce the noise but i don't knoe exactly after making proper grounds to the system the original noise was suppressed and results are clear.
I really did not undestand about grounding methods like how the noise will reduce if it is grounded properly and if not grounded, from where the noise is coming in and I also want how should we know the exact point to where it is going to ground. First how should we came to conclude that which is griund and how it works to reduce noise.

If i am making one more new system how i can decide where should it ground.

Thanks in advance for such a big help.

 

[sophiecentaur]

Hi rama1001
Is this your first amplifier design? It is impossible to answer your question unless you give us a clue about the actual design. If you are using a lot of gain in your circuit then your input stage may need an appropriate impedance - matched to your detector to minimise the effects of front end noise.
A circuit diagram could help either me or someone with a lot of circuit design experience. We need something to go on.

 

[rama1001]

Just leave about the real circuit and i need confirm my self about any system inorder to remove the noise. First point i did not understand about how the noise eleiminated by grounding. In generally, i need to know about how should anyone say, ground will cancel the noise and how can the desiner should think about where he may go for ground.

Quite general explanation i need about ground connections.

 

[sophiecentaur]

I should say that you are just asking for a quick fix rather than to learn something useful. There are thousands of sources of basic stuff on the basics of noise and interference. There is, in fact, no answer to your original question because you need to define your conditions better. What do you mean by "grounding" in this case? Are you referring to where to connect an Earth wire or something more sophisticated? Do you mean 'noise' or do you mean 'interference'? Which 'noise' are you referring to?

 

[rama1001]

right now i am unable to paste the circuit diagram. But tommarow i will paste here. In generally take any circuit, for instance in our CSA(charge sensitive preamplifier) design we grounded the source of a jfet amplifier. Really i don't know the basics about how we can go for grounding on exactly in that location. how the noise will flow through that ground. I did not get two points in any circuit. 1)while designing any system how you can decide which is going to ground(general circuit grounds). 2) how the noise will affect the system if it is not grounded and reduction of noise in the case proper grounding.

If the you are not able undestand my questions i will post another question with reference to any circuit by tommorow.

 

[sophiecentaur]

Your question is so general that it really makes no sense. You are talking about low noise circuit design and general noise theory and there isn't just and answer like "connect point A to ground and your noise will go away", which is what you seem to be wanting.
Why do so many people seem to think the answers must be simple? You will either have to learn something, be more specific or buy a suitable amplifier off the shelf.