need to contruct a 2.1

[bollywoodguyy]

i am a newbie

i need to construct a simple and cheap amplifier for my mp3/vcd player

i am looking at 2 speaker system with one subwoofer.

please guide me.

[dhaen]

Hi Bollywoodguyy,

I'm moving this post to the Chip Amps forum.
There are well regarded designs there that will probably be the most straightforward. Eg Gainclone.
Also there are people there who'll advise.

[soundNERD]

For the satellites, use 2 LM1875 or 1 LM1876. For the sub, use 1 LM3886 or if it is an 8-ohm speaker use an LM3875.

Heres the information on these chips:

http://www.national.com/parametric/0,,811,00.html

[bollywoodguyy]

thanks for the pointer

after buying the amplifier how do i make the connection ?

i bought a capacitor. there are two wires coming out of it (one long and one short). i am looking at a design of circuit and capacitor is shown as |( . which wire (long/short) to connect to which end :- | or (

please excuse my novice questions

[bollywoodguyy]

i did some reading at

http://www.iguanalabs.com/Begtut.htm

it was very helpfull for some basics of electricity

i found a website with a guide to build a amplifier

http://www.reprise.com/host/circuits/lm386.asp

i then went to national.com and downloaded the specification for LM386 with the pin out description (and even bought one from local store)

and pointers into how to calculate the values of the resistors, capacitors using any chip similar to the LM386 ?



I went out today and bought few leds, few resistors, a pot, few capacitors, a multimeter and a soldering rod (25W).

damm...i even fried the soldering rod after 1 hour of use. guess i will need a new one. LOL

i am 16 yrs and this is my first project with electronics people at diyaudio hv been very helpful

[soundNERD]

Hey, a couple of months ago I was asking the same questions, so no problem. What is the value of the capacitor? And what voltage is it rated at?

You are going to need a few capacitors to do this, and a few resistors too. You will also need a transformer (to power it), a rectifier (to turn the AC to DC, some wire and a heatsink.

I would suggest going to www.national.com and ordering some free samples of the chips, rather than buying them.

What are you going to use? the 3886 and 2 1875 or the 3886 and 1 1876? I would also suggest the 3886 and 1 1876. Another idea would be to use an LM3875 for the sub since you wouldn't have to worry about resistors to bring it out of mute mode.

How do you plan to wire it? With a custom made PCB, perfboard, a generic board designed for any circuit, or point to point (no board, just soldering parts directly to the pins)?

The capacitor, as long as it is shaped like a can, should have a row of + or a row of - indicating which is + and which is -. The | in the |( symbol is the positive side, and the ( is the negative side.

As far as a schematic, go with the ones on the datasheet.

Let me know what you decide, and I hope I didn't just confuse you more about the gainclone.

-Mike

[li_gangyi]

a quick question on the 3875 sub...I've tried those in inverted mode...and parelled inverted mode...the subs distorts in mid volumes...izzit because of the slow slew rate of the LM chips or am I missing something?? I jused a low-pass filter at the front end...with a "noirmal" amp...like the p3A...it works ok and gives good bass...but on a GC it distorts like hell...even on low volumes it does it a little...any suggestions to fix it?? oh yes...the sub is 8ohms...

[bollywoodguyy]

thanks again.

Hey, a couple of months ago I was asking the same questions, so no problem. What is the value of the capacitor? And what voltage is it rated at?

220UF @ 25V

actually i bought a few cap and resistor yesterday (but my pervious post was n still is under moderation and this post is also)according to the guide at

http://www.reprise.com/host/circuits/lm386.asp

only thing i cant get is 0.05UF cap over here

You are going to need a few capacitors to do this, and a few resistors too. You will also need a transformer (to power it), a rectifier (to turn the AC to DC, some wire and a heatsink.

i have a old computer speaker adapter - 9V / 1 AMP i will be using that for now

next project most probably will be a power supply (2 - 25V) but i cant find any guide on net ( i live in asia, we dont have 110V VAC which most of the guides assume. we have 240VAC)

I would suggest going to www.national.com and ordering some free samples of the chips, rather than buying them.

I am not in USA ..

[QUOTE]What are you going to use? the 3886 and 2 1875 or the 3886 and 1 1876? I would also suggest the 3886 and 1 1876. Another idea would be to use an LM3875 for the sub since you wouldn't have to worry about resistors to bring it out of mute mode.[QUOTE]

right now i am using a LM386

this is m first project so its ok. maybe next time i will get the good ones

How do you plan to wire it? With a custom made PCB, perfboard, a generic board designed for any circuit, or point to point (no board, just soldering parts directly to the pins)?

i have no experience in soldering. so i am trying to get a breadboard. i searched every local shop but couldnt find one. so i bought a perfboard (the one with lots of holes in it)

i fried my solder tool. here is how i did it. i heated it up , then i touched the tip with the solder wire till there was a lump of molten metal hanging...then drop it over the joint n pray it works. LOL anywayz the solder rod died after 2-3 drops i made.

then i hit the net and searched for solder guide. after reading how it actaully done i laughed my *** off on how i was trying to do it

anyway i am stuck unless i get a breadboard or soldering rod n the 0.05UF cap

The capacitor, as long as it is shaped like a can, should have a row of + or a row of - indicating which is + and which is -. The | in the |( symbol is the positive side, and the ( is the negative side.

Thx m8

As far as a schematic, go with the ones on the datasheet.

i will let you know when i complete the first project. u have been of gr8 help

[JOE DIRT®]

in response to your post li....beef up the power supply as you did not state what you are using

[guitargully]

The capacitor, as long as it is shaped like a can, should have a row of + or a row of - indicating which is + and which is -. The | in the |( symbol is the positive side, and the ( is the negative side.

That would be a polaized capacitor then? if it's a regular one it can go in either way right? the "l" and "(" dont matter as long as there's no "+" by one of them?