New Beginner Project - Ipod Docking amp and speakers

[baggies01]

Hi,

This is my first post in this forum, i have been reading loads of threads over the last couple of weeks and i think im set on what i want to start my first dip in to diy audio with.

Ive got a need for an ipod docking set of speakers. My current plan is for a stereo gainclone amp, power supply and two full range drivers all put into an encloser that houses the lot. My plan is then to use an in cart ipod dock to connect the ipod and provide it with power so it can also be used to charge the ipod/not use the battery at the same time.

I have abit oif experience in electronics, done loads of soldering, point to point and on pcbs so im confident with any of that side of it. i have little experience with designing electronics, mainly only university stuff (mechanical engineering) simple circuits. i have no experience of designing or doing anything with audio though. Im happy using a kit but i want to do something a little different from just soldering a kit together and listening to the result, thats why i want to incorporate a speaker build and amp build into a neat ipod dock.

Im thinking of starting with the amp and im looking at the LM3886 chipamp but i dont really want to wait for 6weeks to get the kit sent from chipamp.com in USA. I thought i would buy the pcb's and then buy the components from farnell.com or equivalent.

im having problems finding the 0.1uF 63v -BC propylene capacitors (x6) without paying the £15 delivery from the US, does anyone know where i can pick these up in the UK?

I just wanted to setup this thread to start a bit of discussion about my proposed project and beginner projects in general.

[Ted205]

it sounds like a good idea to me. I'm wanting to do something with my amplifier. I dont think i would

In my experience you will end up getting stuff from the states through farnel and cpc at some point

I've had a quick search but i can't find the pinouts for the ipod have you found them ?

to make things simple have you thought about the lm4780 in stereo?

[baggies01]

thanks for the reply, i no what you mean, there are a lot of components and i dont wanna get the worng ones. How critical is it that i get the same ones as the kit???!!

[MJL21193]

Originally posted by baggies01


im having problems finding the 0.1uF 63v -BC propylene capacitors (x6) without paying the £15 delivery from the US, does anyone know where i can pick these up in the UK?

Hi,
Are these just bypass caps? If so, monolithic ceramic caps would be a better choice and cheaper/easier to get.

Originally posted by baggies01
How critical is it that i get the same ones as the kit???!!

Not critical. Read here. The circuit recommended by National (the manufacturer) is as good as it gets.

[baggies01]

another question, this is probably a general question. How do you decide what transormer to connect to the amp?

[AndrewT]

Hi,
use the 3886.
For 4ohm speaker use a 18Vac transformer.
For 8ohm speaker use a 22Vac or 25Vac transformer.

Since you're in the UK I suggest you stick with 8ohm.

Do you want or need stereo or would mono do?

Look at the national datasheet. Study it from start to finish.
Take notes of any parts you don't understand and ask what they mean.

Look at fig 2 and note the presence of optional components. They are not optional. They are mandatory for every newbie and most experienced builders as well.
Build an AC coupled version. It must have DC blocking caps on both the input and on the Negative FeedBack (NFB) lower leg.

Will your docking station need very deep bass performance or is size/portability more important?
Then choose the input filters appropriately for your intended use.

[baggies01]

thanks AndrewT, i want pretty good bass response from the unit, but i know you need a lot of capacity in the speakers for a sub. Im going to check out that data sheet but i probabily will have more questions soon.

Cheers.

Ps, what are some good full range speakers for this application?

[baggies01]

In the fig 2, what is the transistor? q 1 3904?

[baggies01]

AndrewT,

I want a stereo amp, i have been looking at the stereo amp pcb's from chipamp.com but i dont really wanna wait the 6 weeks delivery.

If i go for the circuit on the national website taht you showed me, what would i have to do to get stereo, use 2 amplifier circuits and 2 power supplies? or would only 1 power supply be ok?

I think i would rather do it using the national circuit.

cheers mike

[Sparky OR]

I'm no expert, but I made a fairly good portable player using a Velleman P4003 kit (TDA1521)for an easy stereo amp, the MCM aluminum cove speakers slide up and off so they can be spread out. It's not audiophile, but it has a good balanced sound with MP3's. The amp actually is seperate and removable as I have a little Magnavox SE tube amp (6BQ5/6EU7) amp that can slide in it's place.