Group order of non-inverted LM3875 pc boards? Anyone interested?

[BrianGT]

Re: I see

you did not put me in the wiki list ?

that's ok, i'll keep making them the way I am used to, however, too bad for me, I would have thought the thing would have gotten cheaper when as expressed in my earlier message I would have been on the list for 4 ....

J-P

I posted a link to the WIKI list:
http://www.diyaudio.com/wiki/index.php?page=NI+GC+PCB+Group+Order

Please add your entry to the Wiki.

--
Brian

 

[BrianGT]

I am estimating $50 or less for all the parts, pcbs for 2 channels and the power supply (8 x MUR860 and 2 x 4.7uF caps), including packing and shipping. (this is for panasonic caps, not BG. I am considering omitting the BG caps from this order, since I can't seem to find good quantity discounts anyway. In addition, most of the interest for this order seems to be for the Panasonic FC caps.)

I'd be interested in a few boards, caps and resistors. What is the final price looking like?

See my above post. If you want to express interest in the group order, add your name to the Wiki, along with the amount of items that you want.
http://www.diyaudio.com/wiki/index.php?page=NI+GC+PCB+Group+Order

I will give it a few more days to generate interest, then I will work on getting some definate prices. One more addition to the above price list above, is the LM3875, which will add another $8-10 to the order if you don't already have some of these chips.

--
Brian

 

[BrianGT]

Should't there be an option to actually also get the 3875s also, or is everyone going to use sampling?

UVODEE: I think you are supposed to put yourself on the wiki list.
That way your future is in your own hands!!!

Mark,

Good point. I had forgotten about this item, because I initially didn't plan on an entire kit. I do NOT advise exploiting National Semiconductor's sample program for this project. Especially since it is quite a reasonably priced chip.

--
Brian

 

[BrianGT]

Here is my initial layout of the power supply pcb. It is the same size as the gainclone pcb.

My current idea is to put 1 of these boards and 2 channels of the gainclone board one a single pcb.

--
Brian

 

[BrianGT]

schematic for power supply board.

--
Brian

 

[Variac]

Hey Brian, at this point why don't you make it a complete kit pleeeease?

Power Supply:
You could just lump the power supply items together

add the small supply cap to any of the cap choices, i.e. if the big caps are Panasonic they include a Panasonic small cap
If BG, then include a small BG

Maybe you really don't need 2 panasonic cap choices.

Maybe each resistor pack includes the amp chip.

This could be a record buy!!!

 

[Chris Marshall]

Hi Guys

I'm new at this diy thing and this looks a great way to get started.

Brian, are you happy to ship to the UK? If so I'll put my name down on the Wiki.

regards

Chris

 

[BrianGT]

I added a LM3875 category to the table, along with a category for your Geographic Location. I made the LM3875 category the same as the Rpack category. Please check over your information again, and add your Geographic location to the table.

--
Brian

 

[BrianGT]

Hey Brian, at this point why don't you make it a complete kit pleeeease?

Power Supply:
You could just lump the power supply items together

add the small supply cap to any of the cap choices, i.e. if the big caps are Panasonic they include a Panasonic small cap
If BG, then include a small BG

Maybe you really don't need 2 panasonic cap choices.

Maybe each resistor pack includes the amp chip.

Mark,

I am getting close to lumping together everything as a kit. If I can't find a volume discount on the BG caps, I will not offer them as part of this order. I will give this order a week to see how the numbers work out, then I will work out pricing.

--
Brian

 

[KT]

Count me in

I'd be interested in several of the boards. Enough to make a couple of 5 channel home theatre amps or so.

Best,
KT

 

[BrianGT]

Information on Wiki

Here is the link to the Wiki, for those missed it:
http://www.diyaudio.com/wiki/index.php?page=NI+GC+PCB+Group+Order

Please fill out the table. I attached the current view of the table.

Most likely, 2 channels will be combined with a single power supply board, on one pcb, so please keep # of channels to an even number.

Also, please fill in your geographical location, and verify the numbers listed in the sheet.

--
Brian

 

[jean-paul]

What about a single hole in the middle of the board, to relieve stress on the solder joints? With the current positioning of the capacitors, and board dimensions, there is no easy way to put holes on the sides of the boards.

--
Brian

A single hole is OK but when the board would be slightly wider there is room fo a 3 mm hole at the left and at the right.

Never mind, a single mounting hole is better than none at all....

 

[BrianGT]

A single hole is OK but when the board would be slightly wider there is room fo a 3 mm hole at the left and at the right.

Never mind, a single mounting hole is better than none at all....

What about placing the single hole here:

If not.. where would would you recommend placing it, with it not interfering with the layout.

The blue traces are the traces on the bottom of the pcb.

--
Brian

 

[tiroth]

I just updated the totals.

 

[Peter Daniel]

I am interested in 4 boards ( or more ) but I would like to have 3 mm mounting holes at both sides to support the board in the case.

The following comment is meant as positive input:

It seems the amp will be "hanging" at only one screw this way. The weight of the caps will cause mechanical stress at the solder joints possibly causing premature failure. Also the risk of short circuits with "loose" PCB's is higher than with well mounted boards.

This is a very good observation and I also thought about it. Instead of using holes in the board for support, I'd rather use a block on the caps and atach it to the heatsink. This will provide enough support for everything.

 

[Peter Daniel]

Black Gates can be ordered directly from Japan, with at least 30% discount.

 

[BrianGT]

This is a very good observation and I also thought about it. Instead of using holes in the board for support, I'd rather use a block on the caps and atach it to the heatsink. This will provide enough support for everything.

Sounds like a much better idea, but, do you know an easy way to get these manufactured? Would wood be fine for this, or is the white plastic stuff you used on your earlier amps better?

If someone wants to look into this, and get some made, they could be included in with the order if people are interested.

--
Brian

 

[BrianGT]

Black Gates can be ordered directly from Japan, with at least 30% discount.

Sounds like a good idea, but how are the lead times? I once ordered a box of Elna capacitors, and it took me 2 months to get them.

--
Brian

 

[Peter Daniel]

It usually takes 2 weeks and is sent by air mail.

Mounting block can be made out of delrin. It's almost as easy to work with as MDF. If there is enough interest, I could produce them, as I already have experience with that

 

[jlh28]

^expressing interest

That is all