First PCB design - advice needed - Page 1
Forum section: electronics / projects

author: RennenedeBanane
author_rank: Newbie
timestamp: December 14, 2017, 11:04:00 pm
content: Hey there,I just finished my first PCB design, so be indulgently with meI'd like to know what's there that can be improved. I'm sure I made a ton of beginner's errors.Thank you.

author: hermit
author_rank: Frequent Contributor
timestamp: December 15, 2017, 05:01:23 pm
content: First beginners error is not posting the schematic and telling us what you want to accomplish with it.

author: wraper
author_rank: Unknown
timestamp: December 15, 2017, 05:14:52 pm
content: You use extremely small pads for some large components. And it seems C10 and C11 would be impossible to mount with such hole size and distance if silkscreen represents actual cap diameter.

author: ocset
author_rank: Super Contributor
timestamp: December 16, 2017, 03:43:34 pm
content: Here is a document on laying out pcbs with smps on themAlso, the time old favorite by the author of this website, Dave Jones himselfhttp://www.alternatezone.com/electronics/files/PCBDesignTutorialRevA.pdf

author: knapik
author_rank: Regular Contributor
timestamp: December 17, 2017, 10:01:37 am
content: I believe your green highlighted components means that they're colliding with another component. Have you run a design rule check?

author: RennenedeBanane
author_rank: Newbie
timestamp: December 26, 2017, 03:10:04 pm
content: Hello,sorry that I left you without any reply, but Christmas was coming and what's the point of contemplative christmas time without any stress?Quote from: hermit on December 15, 2017, 05:01:23 pmYes, my bad. I attached screenshots of the block diagram and each schematic. I hope, that's helpful. The purpose is a universal soldering station, e.g. a station which can control several soldering irons from different manufacturers.Quote from: wraper on December 15, 2017, 05:14:52 pmI got the pad size for each copmonent from the data sheets. So if I made no error with centimeter and inches, it should work. Or do they seem that small?The silkscreen of C10 and C11 should represent the actual size. So why does it seem impossible to mount them? I have not that much of actual soldering experience, so I' honestly not sure why it shouldn't work.Quote from: treez on December 16, 2017, 03:43:34 pmThank you, I will read it.Quote from: knapik on December 17, 2017, 10:01:37 amYes, there are components where Altium thinks they collide. For example the display, which goes over the entire PCB, but will be mounted on spacers. The problem is currently that I cannot set the rules matching the PCB mill, because my university couldn't say which mill I can use for making the PCB. But if I made no error while creating the components, there should be enough room for each component.

author: TomS_
author_rank: Frequent Contributor
timestamp: December 27, 2017, 12:13:52 am
content: Quote from: RennenedeBanane on December 26, 2017, 03:10:04 pmIn my experience, which isnt necessarily industry experience, a capacitor that big would tend to have a bigger pitch. Perhaps if you can supply the manufacturer and part number someone will cross check. But Ive never tried to design something with so much capacitance, so you might take my words with a grain of sand.

author: wraper
author_rank: Unknown
timestamp: December 27, 2017, 12:31:35 am
content: LOL what, 1N4148?

author: wraper
author_rank: Unknown
timestamp: December 27, 2017, 12:38:58 am
content: How this is supposed to work? PCB layout is the least of your problems.

author: RennenedeBanane
author_rank: Newbie
timestamp: January 10, 2018, 10:38:02 pm
content: Hey guys, thanks for your help so far. I had a talk with my supervising professor and it seems like I have to redo the PCB. But anyway, first to the things you mentioned:Quote from: TomS_ on December 27, 2017, 12:13:52 amdata.tinkertubes.de/TDK_Alu_Elko_Snap_In_B41252.pdfThis is the data sheet for the capacitors C10 and C11.It seems a bit unclear if this size of capacitors has three pins (Quote from the datasheet: "Snap-in capacitors are also available with 3 terminals", so I thought they are available with two and three pins. Also the supplier had a picture showing two pinshttp://fi.farnell.com/epcos/b41252b7109m000/cap-alu-elec-10000uf-35v-snap/dp/2750101). If you want to take the time, I'd be glad to hear your opinion.Quote from: wraper on December 27, 2017, 12:31:35 amOk, I get your point. Thanks for pointing out, I don't want to release the magic smoke. I recalculated the current in the rectifier and chose this diode instead:http://fi.farnell.com/on-semiconductor/sb5100/diode-schottky-5a-100v-do-201/dp/1467531.It's a Schottky, because it was the cheapest I found which fitted the requirements.Quote from: wraper on December 27, 2017, 12:38:58 amI hope I didn't make a complete fool out of myself. The complete topic of hardware design is new to me and I heard of transistors only in theory. But I think I found out why it wouldn't work. I attached a new version which hopefully does work.To make sure I understood it: The problem was that the microcontroler couldn't provide enough voltage in order to make the transistor conduct. With the new setting, the 24V drops at the heating element and the transistor can conduct, since the base voltage can now be higher than the emitter voltage.