Chip amp on the cheap *PIC*

[jaudio]

http://www.diyaudio.com/forums/attachment.php?s=&postid=732722&stamp=1127864428


My 12.32 amp. This is the second cheapest amp I have built.

OPA549 4 Free samples
Case Free(Can buy for $1 goodwill)
Caps and Resistor $.60
Breadboard $1.50(MCM)
Screws $.99
Paint $3.00
RCA connectors $.80 (Jameco)
Binding Post $2.40(Partsexpress buyout)

[hongrn]

http://i2.photobucket.com/albums/y48/hongrn/1.jpg


I thought mine was cheap. Just got this LM4780 from hifidiy.net for $40. Guess yours is ultracheap!

[robertcottiers]

> I thought mine was cheap. Just got this
> LM4780 from hifidiy.net for $40. Guess yours
> is ultracheap!

Hongrn:It looks like a nice kit,good luck with it.BTW If you attach the ChipAmp to the heatsink without an insulating washer,the heatsink will be at V- potential,most people are not aware of this.

***The following is from the LM4780 datasheet*****

Note 14: The TA27A is a non-isolated package. The package’s metal back, and any heat sink to which it is mounted are connected to the V- potential when using
only thermal compound. If a mica washer is used in addition to thermal compound, èCS (case to sink) is increased, but the heat sink will be electrically isolated from
V-.

Regards Bob Cottiers

[trevorg]

> My 12.32 amp. This is the second cheapest
> amp I have built.

> OPA549 4 Free samples
> Case Free(Can buy for $1 goodwill)
> Caps and Resistor $.60
> Breadboard $1.50(MCM)
> Screws $.99
> Paint $3.00
> RCA connectors $.80 (Jameco)
> Binding Post $2.40(Partsexpress buyout)

Whats it do power wise?

[hongrn]

Thanks, Bob. Wow, I didn't even realize that they sold me the non-insulated chip. I read the datasheet on the LM4780 but didn't pay attention to note 14.

Hong

[jaudio]

> Whats it do power wise?

about 80watts per channel

[trevorg]

> My 12.32 amp. This is the second cheapest
> amp I have built.

> OPA549 4 Free samples
> Case Free(Can buy for $1 goodwill)
> Caps and Resistor $.60
> Breadboard $1.50(MCM)
> Screws $.99
> Paint $3.00
> RCA connectors $.80 (Jameco)
> Binding Post $2.40(Partsexpress buyout)

Where could i start to build one of these? I like.

[jaudio]

> I thought mine was cheap. Just got this
> LM4780 from hifidiy.net for $40. Guess yours
> is ultracheap!

It looks like a good set for the price. Is it $40 for a stereo pair? The filtering caps looks very intersting,I will have to look for more imformation.

[jaudio]

> Where could i start to build one of these? I
> like.
First order samples froml <A HREF="http://www.ti.com">www.ti.com</A>

Then look for any alumimun modem or harddrive case(check goodwill,salvation amry or your job. It should cost about $1.) Be sure to get all the cables that come with case

You could salvage filtering capacitors(from broken stereo)or order from <A HREF="http://www.apexjr.com">www.apexjr.com</A>(12,000uf caps 2/$1) but shipping will burst you budget.

All other parts from partsexpress for about $4

LED from doller store keychain flashlights $2

[jaudio]

> First order samples froml <A HREF="http://www.ti.com">www.ti.com</A> Then
> look for any alumimun modem or harddrive
> case(check goodwill,salvation amry or your
> job. It should cost about $1.) Be sure to
> get all the cables that come with case

> You could salvage filtering capacitors(from
> broken stereo)or order from <A HREF="http://www.apexjr.com">www.apexjr.com</A>
> (12,000uf caps 2/$1) but shipping will burst
> you budget.

> All other parts from partsexpress for about
> $4

> LED from doller store keychain flashlights
> $2
I forgot want you order from order OPA549 or OPA541 four pieces and least three DRV134

[robertcottiers]

> I thought mine was cheap. Just got this
> LM4780 from hifidiy.net for $40. Guess yours
> is ultracheap!

Hong:In case you have not purchased your transformer yet,PE has a buyout which would work well for your configuration.They are 25 volt CT,you will need two transformers,and you will not use the center tap wire.This will yield +/-35volts DC after capacitive filtering.PE does not spec a VA rating,but judging from the size of it it will power the chip amps....$5 apiece plus shipping = not bad.Just my 2 cents.

Regards Bob C.

heres the link:

<A HREF="http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=129-084">http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=129-084</A>

[hongrn]

> It looks like a good set for the price. Is
> it $40 for a stereo pair? The filtering caps
> looks very intersting,I will have to look
> for more imformation.

Yes, for the pair. They say you have the option of building a 2-channel amp at 120W/ch, or a 4-channel amp at 60W/ch.

[jaudio]

http://www.diyaudio.com/forums/attachment.php?s=&postid=732724&stamp=1127864535


picture of the back of amp

[jonpike]

> Note 14: The TA27A is a non-isolated
> package. The package’s metal back, and any
> heat sink to which it is mounted are
> connected to the V- potential when using
> only thermal compound. If a mica washer is
> used in addition to thermal compound, èCS
> (case to sink) is increased, but the heat
> sink will be electrically isolated from
> V-.

> Regards Bob Cottiers

Yes, nice kit, looks like good quality caps, as well! They've got a few other interesting ones on their site, too. Hmmm.. been thinking of putting together a chip amp, was going to check back with BrianGT's chipamp boards and kits effort, and here we are with another nice option...

A note on the heat sink situation... you do have to electricaly isolate your heat sinks, but the advantage of this package is you do have the lower thermal impedence to it, nothing but metal on metal. (and your high quality heat sink compound, of course) This will let you stay cooler/burn more watts, without problems.. I'd probably pick the non insulated type given the choice..

And, a question... how's the documentation? I tried to find any on their site, was wondering what transformer reccomendations they gave... voltage and wattage.

[cjd]

> Thanks, Bob. Wow, I didn't even realize that
> they sold me the non-insulated chip.

They don't *make* an insulated LM4780!

C

[cjd]

> A note on the heat sink situation... you do
> have to electricaly isolate your heat sinks,
> but the advantage of this package is you do
> have the lower thermal impedence to it,
> nothing but metal on metal.

This *is* a possibility, but it means your heat sink is at V- and that's bad news for *any* type of accident that may happen. You know, drop a screwdriver that connects the HS to chassis... ;)

My choice would be to use a copper heat spreader bonded to the chip, and insulate the heat spreader with a thin mica or silpat or something similar.

:)

Just be careful and make darn sure it's isolated properly.

C

[colby]

> My 12.32 amp. This is the second cheapest
> amp I have built.

> OPA549 4 Free samples
> Case Free(Can buy for $1 goodwill)
> Caps and Resistor $.60
> Breadboard $1.50(MCM)
> Screws $.99
> Paint $3.00
> RCA connectors $.80 (Jameco)
> Binding Post $2.40(Partsexpress buyout)

What about the power supply?

Am I the only one who can't see the pics?

[jaudio]

> What about the power supply?

> Am I the only one who can't see the pics?

Here is a picture.

[jaudio]

http://www.diyaudio.com/forums/attachment.php?s=&postid=639093&stamp=1115719976


> What about the power supply?

> Am I the only one who can't see the pics?

Here a picture

[bill]

[jaudio]

http://www.diyaudio.com/forums/attachment.php?s=&postid=639090&stamp=1115719776


I dont know why you cant see the picture but I will post a different picture. Hopefully you will be able to see it.

[nef]

We can't view it because the picture is hosted on another forum as an attachment. I think we have to register at that forum in order to view it.

[jaudio]

> We can't view it because the picture is
> hosted on another forum as an attachment. I
> think we have to register at that forum in
> order to view it.

Is there any way to post picture directly,with using a link?

[nef]

Not from that forum. You need your own hosting or a free image host. Try this: <A HREF="http://www.imageshack.us/">http://www.imageshack.us/</A>

> Is there any way to post picture
> directly,with using a link?

[jaudio]

> Not from that forum. You need your own
> hosting or a free image host. Try this:
> <A HREF="http://www.imageshack.us/">http://www.imageshack.us/</A>

Sorry I tried to use imageshock but I could not get the picture to link. So that is another thing that I have to learn. I think it is about #10 on my list,so it will months before I get to it. Again my apologies

[nef]

http://img240.imageshack.us/img240/1364/p1010004s7pw.jpg


You had it, the link was pasted down wrong thats all. Had some extra characters that made it not show. Got the email with your reply to the message with links so I looked at them. Heres the proper link that needed to be copied.

<A HREF="http://img240.imageshack.us/img240/1364/p1010004s7pw.jpg">http://img240.imageshack.us/img240/1364/p1010004s7pw.jpg</A>

I copied this link into the "Optional Image URL" field.

Have any questions just email me, i'll try and get you all sorted out. Its the best I can do to repay the forum back for the help its given me.

> Sorry I tried to use imageshock but I could
> not get the picture to link. So that is
> another thing that I have to learn. I think
> it is about #10 on my list,so it will months
> before I get to it. Again my apologies

[jaudio]

http://img240.imageshack.us/img240/901/p10100037zx.jpg


another try

[jaudio]

http://img160.imageshack.us/img160/2591/p10100080ss.jpg


A picture of the front. The front is still not quite finished.

Thanks alot Nef