Heart Keychain - Page 1
Forum section: electronics / projects

author: ColdKeyboard
author_rank: Contributor
timestamp: November 13, 2017, 04:40:03 am
content: I've recently published a post aboutDIY Heart shaped keychainthat I've created to be gifted to my friends and family.It's extremely simple design and it takes couple of hours to make but it make a great present. A lot of people loved the idea of gifting somethingthat is unique, cool and "hand-made".Holidays season is fast approaching and after that Valentine's day (it looks far away but consider that PCB fab houses close in January and also it takes 3-4 weeks to get your design to your doors... it's not that far away).Anyways, here is how it looks and alsolink to original post.p.s. Note that firmware is not the greatest one. It works, but you might want to improve it to get more battery life as well as pick your parts so they are optimized for low-power design.I would love to hear your thoughts

author: Ian.M
author_rank: Super Contributor
timestamp: November 13, 2017, 07:39:19 am
content: There's no way that will survive in a pocket with keys. It has better odds in a handbag, if the owner is obsessively tidy.The MCU's too close to the attachment hole, SMD parts will get knocked off, and the hole is so close to the board edge that the FR4 will almost certainly get chewed up by the keyring. Add a 3D printed ABS plastic back and it will survive a bit better, but not well, as the LED 'eyes' are still very vulnerable.

author: jaycee
author_rank: Regular Contributor
timestamp: November 13, 2017, 11:58:47 am
content: Another alternative.. pot it with some clear compound

author: ColdKeyboard
author_rank: Contributor
timestamp: November 16, 2017, 03:33:01 am
content: Thank you for suggestions, I'll definitely consider those if I opt for another revision.Right now I have gifted about 8 or 9 PCBs in total. So most of them are in use for about 6 months, and surprisingly they all work fine without any issues.Also what surprises me that only on one pcb silkscreen got small scratches, rest of them are as good as new.

author: Ian.M
author_rank: Super Contributor
timestamp: November 16, 2017, 06:11:31 am
content: One large improvement woud be to skew the battery holder footprint enough to move the ring hole to the other lobe. That would vastly reduce stresses on the circuit round the MCU. Put some Kapton tape over the MCU and associated components then solder a tin plate screening can over them to provide physical protection, and it would be about as robust as you could make it without completely revising the concept.Note that due to the large exposed battery+ contact, the board should *NOT* use a conventional groundplane to reduce the risk of a shortcircuit. Instead the plane should be battery+, which will be just as effective for decoupling to.

author: ColdKeyboard
author_rank: Contributor
timestamp: November 18, 2017, 01:03:08 am
content: Quote from: Ian.M on November 16, 2017, 06:11:31 amThanks, that sounds like a great idea. Now the goal of this project wasn't to give a finished project that someone will do copy&paste and have something ready for packaging and mass production. It was about me goofing around and tryingto find a way to gift something unique to people I love, and opening it to community shares my idea and let's anyone work on it and improve it and most of all getting the satisfaction of seeing that my idea inspired someone to get their feet wet with electronicsor to do something awesome.