Circuit and PCB design - Page 1
Forum section: electronics / beginners

author: Eosander
author_rank: Newbie
timestamp: February 10, 2018, 10:09:13 pm
content: It's been an awful lot of years since I studied electronics. Nevertheless I have made an attempt to design a circuit needed for my model boat.Basics: It's an On-Off circuit, controlled by a magnet (the Reed-contacts and the Bistable relay) first phase activates a 5VDC supply to the receiver, second phase, after a time delay of approx 4 seconds, activates the main relay for 12VDC to the consumers.I have attached a couple of pdf documents, to which I'd appreciate some feedback.Although some parts are in Swedish, I am convinced that the people, familiar with this kind of stuff will understand the sole purpose of it.One pdf is the circuit diagram, and the other is my attempt to a PCB layout, on which the yellow one is the component side, and the black/grey one is the soldering side.Comments appreciated.Found an error in the PCB layout todaySo now I have replaced it with a picture.

author: phil from seattle
author_rank: Super Contributor
timestamp: February 11, 2018, 05:56:43 am
content: It's generally better to just post images. People are generally suspicious of PDFs.Why the heat sink?

author: Eosander
author_rank: Newbie
timestamp: February 11, 2018, 08:56:55 am
content: I made them pdf, since I thought that format is available for most people.I chose to put a heat sink, in case the 5VDC-consumption becomes high,and according to the TI description of the LM2676, it becomes more stable with cooling.

author: soubitos
author_rank: Frequent Contributor
timestamp: February 11, 2018, 09:04:03 am
content: What is the current requirement on the 5v rail generated with the LM2676?

author: Eosander
author_rank: Newbie
timestamp: February 11, 2018, 09:25:12 am
content: I have no figures yet; The plan is a 7-channel receiver for the functions needed on the model, here inccluding a couple of power servos.The 5VDC is to be used for the radio, as well as necessary illumination of the ship - here I have plans on using LED:s.The LM2676 is said to have a maximum rating of 3A, which should be enough.

author: tooki
author_rank: Super Contributor
timestamp: February 12, 2018, 12:52:34 pm
content: Quote from: Eosander on February 11, 2018, 08:56:55 amYeah, I certainly do not agree that “people are generally suspicious of PDFs”.That said, because of how the forum software handles PDFs, they’re super annoying on iOS, because it wants them to download into a PDF viewer app, rather than displaying them in Safari. So images like JPEG, PNG, and GIF are nice for us who like to browse on iPad, since they just show up without fuss. (The forum admins don’t seem to care about this, they similarly have ignored repeated requests to add the .jpeg file extension, which is what iOS uses when uploading images.)

author: phil from seattle
author_rank: Super Contributor
timestamp: February 13, 2018, 02:07:26 am
content: There are pdf exploits.One of many pages about this topic.

author: tooki
author_rank: Super Contributor
timestamp: February 13, 2018, 02:42:15 am
content: Quote from: phil from seattle on February 13, 2018, 02:07:26 amThe existence of exploits isn't under dispute. What I dispute, vehemently, is your claim that "People are generally suspicious of PDFs."No, they aren't.One might argue that theyshouldbe, but they certainly are not.Somepeople (a tiny percentage) are suspicious, but not a majority as you are claiming.

author: Eosander
author_rank: Newbie
timestamp: February 25, 2018, 07:53:31 pm
content: Thank you for maintaining focus on the subject, I'd be sad if someone discussed something off-topic in this thread.

author: Brumby
author_rank: Unknown
timestamp: February 26, 2018, 02:30:06 am
content: New thread:Are PDFs dangerous?https://www.eevblog.com/forum/beginners/are-pdfs-dangerous/

author: rsjsouza
author_rank: Super Contributor
timestamp: February 26, 2018, 02:37:21 am
content: One question: did you run your circuit using the Webench? It may give you some ideas about the influence of different setpoints of your input voltage, output current and it may give some component values that are more optimized for your boundary conditions.