Tuesday, December 13, 2011

A Small Part Quest

It is the journey or the quest, and not the destination, that keeps life interesting.

Server years ago I started a goal or strategy for my self, by attempting to build my projects as small as possible, using the smallest parts that I could find. But, one particular part has been problematic, that is, I have a problem with the size of the available "1/8 inch stereo jacks".

My early projects contained stereo jacks from Radio Shack or other sources, they were big, clunky and were mostly the panel mount style, they have a large foot print when mounted on a PCB. Some jacks have built-in switches, which is nice but I seldom use.

My quest has been to find a much smaller - 1/8 inch (3.5 mm) stereo jack.

EBay - USB Sound Card
I noticed there are two very nice small stereo jacks used in the very small USB sound cards, which are available from eBay. These small USB sound cards can be purchased for as little as $0.75 each. I have been using these sound card with headphones on my desktop computers.

Because I had purchased several extra USB sound cards, I decided to try to salvage the stereo jacks for one of my small projects. With a lot of time and work, I finished with two slightly mangled jacks.

The Desired Stereo  Jack
found in USB Sound Cards
The difficulty was the small spacing between jacks on the sound card made it extremely difficult to; cut-out, de-solder, or remove the six through hole leads from their small circuit board. The non-lead solder makes the task just that much more difficult.

The image suggests it is a SMD, but the installed jacks in the USB Sound Card are through hole, with small vertical pins. Once removed, I generally cut the pins very short to set-on and solder to SMD pads.

Project Using
Salvaged Stereo Jack
Here is one of my previous projects, using a salvaged part. It is a very small 30m FSK and CW Transmitter, all mounted on the side of a 9 Volt battery.

I liked the obtained salvaged part, because of its very small foot print. I decided to try to obtain new similar parts from the normal suppliers.

But, all I had was my contrived description of what I wanted. Searches through Mouser and other suppliers did not provide help. They had larger parts, and I settled for the smallest part they had, I purchased several.

Mouser Stereo Jack
PN 161-4034-E at
$0.75 in lots of 100
In the drawing, the Mouser parts looks small, but it is actually about 50%  larger than desired. The part used by the USB Sound card must be available from some vendor. But I did not have a part number to help with the research. I searched my standard/normal Local and Chinese suppliers. Again, lack of a part number, made it difficult.

For about a year, several projects were created and laid up with the much larger Mouser parts.

Only recently, did I inadvertently come across a part number of the desired small part on a published product schematic/drawing, it is - PN MJ4435-R.

Now I had something to find. My favorite part search engine is FindChip, which indicated the part was available from Newark at $2.76 each. Dang, I am not willing to pay that much for the jack, when I could salvage two from a $0.75 USB Sound card.

So, back to the drawing board and lay up of PCBs with the larger Mouser part, or I would have to continue to spend time salvaging parts from USB sound cards.

Recently I created a small project that I am thinking of selling. For it, I want the best parts available. The size of the board is smaller than the available stereo jack from Mouser. I will have to bite-the-bullet and purchase the part from Newark at $2.76 each. That, of course, makes my product just that much more expensive. I attempted to placed an order for 10 parts, but then . . .

The BAD News is; there is a $20 surcharge on the order as this part is supplied and shipped direct from a non-US factory. And, there is an additional sales tax on top of that (all of this could make these little parts very expensive).

But, the GOOD News is; during checkout, I noticed that the price is $2.76 for a package of 5 parts !! ( a detail that I missed before). That will make the individual parts much cheaper than expected.

It is more than I wanted to spend (for my initial product parts order), but instead of 10, I ordered 100 stereo jacks from Newark, just to keep the individual price as low as possible. My cost for the stereo jack will be about $0.85 each.

It could be argued that the Mouser part (number 161-4034-E) at the same price is of better quality, but there is a lot to be said for simpler (which I think is a more elegant design) of the MJ4435-J part, which exposes its complexity on the outside and hides nothing on the inside.  I would think the simplicity and unique design of MJ4435-J parts should sell in the US for around $0.40 ea. Especially as two are sold with each USB Sound card that sells for very little money.

So with all of that, and if all goes well, you my soon find an interesting little product, available here, with a very small stereo jack.

So, the quest goes on, for yet, ever smaller parts and small projects.


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