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Old 26th October 2012, 08:37 PM   #11
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reflow- scrounge parts from discarded electronics. We have all done it. Dont hurt yourself.
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Old 26th October 2012, 10:05 PM   #12
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I have a question...
I'm wondering if I should ditch my home built amplifier and buy a simple car subwoofer amplifier from walmart..
should I really simply buy one from walmart? or should i stick to my home built amp?
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Old 26th October 2012, 10:44 PM   #13
sreten is offline sreten  United Kingdom
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Quote:
Originally Posted by realflow100 View Post
I have a question...
I'm wondering if I should ditch my home built amplifier and buy a simple
car subwoofer amplifier from walmart..should I really simply buy one
from walmart? or should i stick to my home built amp?
Hi,

The answer so far is, Yes, simply because you so far have simply
no idea what you are talking about, and simply refuse to take on
board any of the simple theory alluded to and explained to you.

Buy it, and then work out why it is so much better, and why your
battery lasts so much longer and why it is so much more powerful.

rgds, sreten.
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Last edited by sreten; 26th October 2012 at 10:49 PM.
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Old 26th October 2012, 10:58 PM   #14
adason is offline adason  United States
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...just do not ditch your day job
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Old 27th October 2012, 12:00 AM   #15
kevinkr is offline kevinkr  United States
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Guys, let's tone down the snarky comments directed at the obviously inexperienced OP a bit OK? I don't think I need to spell out who this is addressed to..
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Old 27th October 2012, 10:47 AM   #16
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I'm not sure exaclty if the battery would last any much longer... because car amps drain lots more power much more quickly and im thinking huge amounts of power..... and if it drains so much power it could cause almost a short on the battery if it drains loads of power....
is this correct? or would it not drain as much as my home made amplifier? (my home made amp doesnt drain too much power at all.... it can even run off a single salt water home made battery although not that loud but it works)
do i need slightly more than exactly 12 volts? possibly 12.5 volts to keep the voltage more constant.
and should i buy a capacitor for the amp too? im thinking i would need one to keep the voltage from dropping below 12 volts
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Old 27th October 2012, 07:03 PM   #17
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Assuming that you didn't change the design (which was vaguely described in other threads), you're using a class A design which draws a lot of current at idle. Common car audio amps are either class AB or class B and draw very little current at idle.

A capacitor on the power side of the amp will do nothing to keep the voltage above 12v.

The maximum current draw will be determined by the power produced by the amp. For common car audio amps, the current at low power is minimal. The current at full power depends on several things. All else being equal, the full power current draw will be determined on the rail voltage supplied to the output transistors and the speaker load.

If you really want to learn to design amplifiers, you first need to learn about electronics. This will take some effort on your part. The basic car audio electronics website (link below) will help you if you read it carefully from top to bottom. After you have read and understand most of that, you can move onto websites or books that go into more detail for proper amplifier design.

You can continue to try to make an amplifier but you'll likely never build that will be as the cheapest amp that you can buy on ebay or walmart. Amplifier design requires a good understanding of the basics.

Think of it this way... Lets say that you gave someone all of the materials to build a house but that person didn't even know precisely what a house was... and then you gave the same materials to a contractor. Which one do you think would produce better results?
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Old 27th October 2012, 07:49 PM   #18
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i'm not saying the capacitor is going to keep the voltage above 12 volts but keep it from going below 12 volts or at least keep it from going under 11.9 volts so my amp doesn't turn off when the bass hits and drops the voltage coming from the power supply
i'm only going to be using a 12 volt DC adapter with only 2 amps. since I don't have a car battery on hand.
I'm not going to change my amplifier or modify it anymore but instead i'm just going to walmart to buy a decent one instead.

and one of my 2200uF capacitors accidentally split open when i was putting it into a little plastic case and it dripped stuff on my hand! EW!
I washed my hands off really quickly with lots and lots of water
is it poision or acid? is it going to make me sick or burn my hands? i cleaned it up with tissue paper and washed my hands again.
is it dangerous? what is it?
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Old 27th October 2012, 08:05 PM   #19
sreten is offline sreten  United Kingdom
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Hi,

A supply decoupling capacitor is never a bad idea on a circuit board.

Please stop talking nonsense. Your amplifier draws constant current
all the time irrespective of the output level or input level or no signal.
For that current level it produces very poor maximum output power.

Its very much the wrong way of going about building an amplifier
for battery power than maximises battery life and output power.

rgds, sreten.

Having checked out Walmarts online site, look at :
http://www.parts-express.com/brand/lepai/471
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Last edited by sreten; 27th October 2012 at 08:15 PM.
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Old 27th October 2012, 08:10 PM   #20
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I'm talking about using the capacitor for the car subwoofer amplifier that im going to buy from walmart! like a sony xplode or rockford fosgate or whatever I find at walmart..
not for my terrible home made amp D:
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