Volume control...?

blmn

Member
2001-02-01 2:43 am
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Hi,

The SGS-Thomson site (www.st.com) has datasheets and application notes of many IC power amps, from 1 to 50 watts.

Some of them have built-in gain controls and these controls are usually out of signal path circuits. It means less trouble with noise and other problems.

Regards
 
I once built a variable DC power supply. It uses a pot to adjust the output. So, I bet that would work for an amp. You simply use this to increase or decrease the power supply.

Anyone see a problem with that?

I can't remember what it used. It's a small transistor looking thing. Variac, triac... anyone know what I'm talking about? This was 12 years ago.
 
A potnetiometer is a three terminal resistor. Two terminals are across a fixed resistance, while the third is an adjustable connection anywhere along this fixed resistance. When you turn a knob on a pice of equipment, chances are you are turning a potnetiometer.

It is connected in a circuit like an adjustable voltage divider. Alternatively it can be used as an adjustable gain resistor in an opamp feedback.
 

grataku

Member
2000-12-31 9:31 am
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Hoffmayer,
you have little to be joking about, thespeakerguy was sincerely trying to be helpful. Personally, I think this website needs to crank-up it's level a couple of notches. A multiple choice admission questionnaire is in order in my opinion. If you don't know what a potentiometer is you probably shouldn't be building any audio stuff, if you think that is ok to shorten the output of your zen amp at startup in order to prevent transient noise you probably should not be building any audio stuff, either. That is for your safety and the safety of your loved ones, too.
It seems that some people are expecting to be spoon-fed the knowledge they need by asking the stupidest questions rather than trying to open a book and teach themself something.
 
grataku said:
Hoffmayer,
you have little to be joking about, thespeakerguy was sincerely trying to be helpful. Personally, I think this website needs to crank-up it's level a couple of notches. A multiple choice admission questionnaire is in order in my opinion. If you don't know what a potentiometer is you probably shouldn't be building any audio stuff, if you think that is ok to shorten the output of your zen amp at startup in order to prevent transient noise you probably should not be building any audio stuff, either. That is for your safety and the safety of your loved ones, too.
It seems that some people are expecting to be spoon-fed the knowledge they need by asking the stupidest questions rather than trying to open a book and teach themself something.

I didn't ask what the potentiometer was, but rather how is it used in this case... yes, the amp I'm building is my first one, it is done as part of my studies ( I need to do some project there... ) It's going to be based on IC's, and I asked, because after many hours of searching in the net and books at local library I still hadn't found way to build simple volume control ( I don't want tune/balance...etc...).

And I would like to thank Thespeakerguy for help... :)
 
Grataku and Hoffmeyer, you are both wrong!

This forum is not just for experts. If you want us all to be experts, go somewhere else.

I have learned more from the people here than in any book. You can't read about someone else's experience in a book!

It would take me hours to reverse engineer the Zen, but Vince knew what was wrong in seconds because he actually built one!

pixie
 

grataku

Member
2000-12-31 9:31 am
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Pixie,
you don't need to be an expert, I am no expert myself. What I would like to see is at least some kind of effort.
Don't take it the wrong way but, for instance, it took you 205934 posts just to get the zen to work and most, it seems, was just for moral support. If you spend a little bit less time whining and a little more time thinking and going over your work you could have saved yourself money and time.

Just my 0.000002
 
Yikes!

I think this is an excellent forum! Thanks to all who have helped me in areas where my knowledge is less than complete, and I hope that I have been able to help others with different areas where their knowledge is less than complete. This is still a very new forum (others that I visit have well over 14,000 members!) and as it grows and more people become aware of it, it is very likely that the experience and knowledge level of the members will diverge considerably!

There was once a time when all of us knew nothing about this topic, and someone took the time to help educate us. I'd like to see more tolerance for these differences... Perhaps we could create an "Advanced" thread, and maybe create some links to pages more with basic principles of electronics, definitions, etc to help people over the learning curve...
 
Good idea.

Good idea, Eric.
I think it would be useful for many people.
BTW, I know how a potentiometer works, but I don't know how to design my own class-A amplifier.
Who cares?, everybody say...Me!
I'd like to, but I haven't found a good COOKBOOK about...
I don't care about semiconductor's physics, I need something more 'practical' if you know what I mean...
Greetings.

PS I think this is a good forum.