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i want to build this circuit to power some speakers for my pc but there is a few points i would like help with
where would i put a volume control in this circuit
i need a psu for it ,i have a transformer with an output of 17v that i can
use.
A stereo volume control can be connected to the inputs of that amp.
Its absolute max supply voltage is 18V, so a 17VDC supply would probably be too high when the amp is not playing loudly. It is made for cars with a 14.4V supply, and it can provide 4W to 5W to each 4 ohm speaker. With 8 ohm speakers its outputs are only 2.5W to 3W each.
Oh yeah, if your transformer is 17VAC, then it will give a rectified and filtered DC output of 22V when fully loaded and higher when it has a little load. Way too high for your amp.
It is apparent from the schematic that all the micro-fahrad values
are written uF,
except that one.
Which is written mF, and i think that one micro fahrad is a bit
small to put in series with a speaker.
I dunno.
Why should that one be different ?
Is it one micro-fahrad ?
Hi John,
It is for a car amp with only 4W to 5W output per channel into 4 ohms, probably for those little 3.5" speakers at the front. The 1000uF (1mF) output cap reduces the power at 40Hz to half, but the little speakers can't go lower than about 120Hz anyway.
My computer speakers are 3". Their 4 ohms are driven by a bridged amp for each one which drives them to 12W each from a big, heavy 12VDC wall-wart AC adapter. Since their amps are bridged, they don't have output coupling caps reducing the bass and they rock!
My computer speakers actually move toward me for each beat of the music. The puffing from their vent at their rear propels them. :lol:
It is apparent from the schematic that all the micro-fahrad values
are written uF,
except that one.
Which is written mF, and i think that one micro fahrad is a bit
small to put in series with a speaker.
I dunno.
Why should that one be different ?
Is it one micro-fahrad ?
As aibelectronics said, it's clearly labelled 'm', which means 'milli' and is a perfectly valid prefix for a capacitor, although it is true that it's very rare to see it used. So 1mF (m=10^-3) is 1000uF (u=10^-6), it could also be labelled 0.001F as well, all three are the same thing.
Your PC clearly has a decent audio side.
Mine i'm afraid has packed up.
I think this may be my fault, i vaguely recollect fiddling with the
settings a long time back, and now it won't play properly.
Thanks for pointing out that an mF is actually a thousand uF,
which puts that capacitor back into my concept of acceptable for the
job it is doing.
So its actually not one micro-fahrad, its 1000 uF.
I never met the term until about 1980's then i forgot about it,
there have been a few alterations here and there that i still get
wrong from time to time. But mF is getting used much more lately so
i don't think that will catch me again.
Now i spose i should try to get my PC sounds working properly again.
Regards, John
Note,
Ive just seen Nigel's post,
I don't type very fast, one finger ... cheers Nigel.
Hi John,
My pc speakers came with my new pc. I couldn't believe their heavy weight for their small size so (of course) I peeked inside. The little 3" speakers have a nice rubber surround and a huge magnet. I don't recognise the logo on the power amp ICs, they are Chinese.
They look something like these:
They look very nice, they look quite beefy for their size.
As to my sound problem, ive had a think, and its never worked right
since i installed Win98se in favour of WinME which i didn't like much.
Actually i'm not sure it worked properly when it was WinME.
If you have any advice about the sound settings, i would be grateful
especially if it makes my sounds work again. I did some more fiddling
around a few days ago, and then i was able to play MID files, but
then i tried to get it to play MP3 files after fiddling about some
more, now it wont play more than the first three and a half seconds of
WAV files. Nothing else at all.
So i've picked a short 'ding' for my mail notification.
Its very annoying.
Mainly cos i don't know what i'm doing.
Hi John,
I don't know about your pc's sound settings 'cause my old 486 pc ran Win98 perfectly and now my new pc has WinXT.
I was very lucky. My son bought a laptop from E-bay. It was previously owned by a dj and had GB's of the latest MP3's on it. I copied them to my pc.
Recently my son and I were lucky again. He found a guy who was giving away unrepaired products from an audio-video chain of stores. Stereos, cell phones, wireless phones, CD burners, and portable MP3 players c/w earphones and batteries.
I took most but concentrated on an MP3 player with a 6GB hard drive and there was 4 of them and an owner's manual. Two were smashed, one has a hard drive that makes noises like it is broken and the 4th was intermittent.
The 4th's problem was because it was built with a faulty control pushbutton switch. I removed it and the thingy works just fine. I removed a switch from one of the others and replaced it (surface-mount switches aren't fun to de-solder and they were also glued down) and now I have a portable MP3 player that holds about 1000 songs. I upgraded its firmware from the internet and got its latest 2005 control software for my pc.
It sure isn't a tiny and lightweight ipod-Nano since it is the size of a CD player and weights 320 grams, and its Ni-MH battery (it came with it) lasts only 4 hours per charge, but hey, it was free! :lol:
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