JPL 3.5 mm PCB - an open source, inexpensive, and easy to assemble 3.5 mm jack breakout board

Buying parts off Amazon can be a quick easy way to get something. But the tradeoff is twofold: Amazon products tend to be of low quality and relatively expensive.

Take the 3.5 mm jack. I use these a lot as many of my projects involve audio. There are a few options to buy them online, but none are fully satisfactory.

A single board from a reputable brand such as SparkFun will set you back $4.50. Adafruit's offering is $1.75/board. The Amazon boards which I used were $9.99/6 boards, or around $1.67/board

These boards aren't sophisticated. They are single-sided and have one component. Considering this, I decided that in the long run, it would make financial sense if I designed and manufactured my own boards at scale.

Board

Introducing the JPL 3.5 mm PCB - an open source and inexpensive 3.5 mm breakout while being even more functional than the mainstream boards.

The board uses the 'SHOU HAN PJ3F07-5P' plug. The plug is THT and easy to solder, and it has the neat feature of having pass through pins. The way they work is similar to how audio works on a laptop. When nothing is plugged in, the plug passes through the audio signals to the pass through pins, which are in turn connected to the laptop's speakers. When headphones are plugged in, the pass through connection is physically broken and the audio goes solely into the headphone jack.

The board is compact at 15x20 mm, and breaks out the signals to a .1" header footprint, making it breadboard friendly.

Cost

To calculate the predicted cost, I'll use the price for minimum quantity of each component, with the connector being sourced from LCSC and PCBWay in China. Keep in mind that the cost per board will diminish with higher volumes

All prices not including shipping

Component	Cost (USD)	Units
PJ3F07-5P (3.5 mm plug)	0.60 (0.06/unit)	10x (10 min)
PCB	5.00 (0.50/unit)*	10x (5 min)
Total	5.60 (0.56/unit)	10x

*PCB Quantities are priced somewhat arbitrarily at low quantities and with small boards. (ie 30 boards costs the same as 5x) Fab houses also give lots of coupons and deals which could even lead to you paying nothing on the first order. Be sure to do your research and play around with different quantities to make sure you are paying the best price.

Board	Cost/Board (USD)	Ext. Price (USD)
Sparkfun	4.50	4.50 (1x)
Adafruit	1.75	1.75 (1x)
Amazon (Treedix)	1.665	9.99 (4x)
JPL	0.56	5.60 (10x)

The JPL board comes out to be nearly 3x cheaper per unit than the Amazon board, which it very closely resembles and has equal functionality to.

Treedix board (left) vs. JPL board (right)

Conclusion

If you are interested in making the board for yourself, be sure to check out the Github repository for more technical information and necessary files. I've included all gerbers, KiCad project files, documentation, and 3D Models necessary.

I plan to revise this board in the future to include holes for fasteners and perhaps other features as well. Until then, the board functions super well as it is and even better than some of the commercial options at a better price!

Until next time.

Justinas