Understanding your circuit - Page 1
Forum section: electronics / beginners

author: PR1OR
author_rank: Newbie
timestamp: September 26, 2022, 10:01:34 am
content: Hi All,Firstly Apologise for what is the most basic of questions here. I have very very basic education with electronic and therefore just need to understand the design process and how you calculate certain things.So i am working on a 3d printing project where i want to install a custom PCB.I know what my feature components are i.e USB-C, HDMI etc...But i don't know how i would work out what functional components i.e Resistors, Transistors, capacitors etc...If anyone is able to suggestion the thought process behind working it out i should be able to do it. I understand what each of the functional components does (and if i don't i think i can research that fairly easily) i just don't understand how i would out whats needed for each feature component.How i would assume i need to work this out would be to draw a basic circuit with the feature components with board input. then work out what each feature component input/output voltage/power/current is needed and put the components in to suit. Does this sound about right?Any help would be soo appreciated

author: jonovid
author_rank: Super Contributor
timestamp: September 26, 2022, 10:38:58 am
content: every conductor has potential. may your electrons get to move as intended.

author: PR1OR
author_rank: Newbie
timestamp: September 26, 2022, 10:58:42 am
content: sorry im alittle confused on what you mean?

author: Old Printer
author_rank: Frequent Contributor
timestamp: September 26, 2022, 01:52:52 pm
content: Firstly, a far more detailed description of all of the functions you are trying to make happen would be needed. Second, while it may be possible to assemble a few ready made sections, like a USB to serial converter, or a video board, if you want to design and build a system from the resistors and transistors on up you are in for a project that many call a profession.

author: rstofer
author_rank: Super Contributor
timestamp: September 26, 2022, 03:20:53 pm
content: Learn from somebody else. Just buy a complete control system and reverse engineer it. Or just use it the way it came. There is no way in the world you are going to create one for just $40 or $60https://www.amazon.com/Aokin-Printer-Controller-Arduino-Heatsink/dp/B07Q5R6YSKIt is likely that these motor drivers are too small if you are using larger motors but that's easily substituted with drivers from AutomationDirect or elsewhere.If you are building a large 3D printer, like my 3D mill, you will want a controller like SmoothStepper running from Mach3 software. Then 3 large motor drives and large motors and you're good to go.Search with Google, there are thousands of Arduino based 3D printer projects.Here's a larger setup from Amazon:https://www.amazon.com/Longruner-Arduino-Professional-Mechanical-LKB02/dp/B072N4FMRN

author: PR1OR
author_rank: Newbie
timestamp: September 26, 2022, 04:41:12 pm
content: so to add some context. this project isn't to build a 3d printer but to build a product using a 3d printer. The product is a glorified laptop dock but with (hopefully) more bells and whistles. I know and appreciate this isn't going to be cheap, especially at such a low volume (I'm currently just building this for myself). I like the idea of being able to fully design all parts of this, and potentially the entire production too however i realise this is even more ambiguous on an already very ambiguous project.3d printing project = a multi use charging system. I would (ideally) want to have 2 dedicated USB c lines with data transfer for my phone and watch, another dedicated USB C for my headphones. i will want a USB c output cable that can connect to my laptop, i assume this will also need data transfer as i would like it to both charger the laptop and also to send a display if one or both of the HDMI ports are in use. as i have just mentioned i would like 2 hdmi ports also. i would like to have 3 USB b with data transfer also but these don't have a specific use right now and 2 non dedicated USB c ports for charging only. To top everything off i want to install a laptop battery into the unit so it can run off both mains or battery power. Battery so it can just be used as a wireless charger with the potential to also charge my laptop if necessary and mains to charge the battery and connect to the monitors/phone/watch etc...... finally i want this unit to have a USB-c mains input. I have a USB c laptop charger which is 130W. This is my ideal solution but not my final solution.and i realise this is not just a profession but a highly skilled profession. So I'm not expecting this to be completely possible but i feel like one is better off scoping all desired features and reducing it down to what is possible. One reason is suspect everyone will tell me this isn't possible is because i'm struggling to find docks or USB extenders with lots of USBc's 2/3 seems to be standard. Im sure this has something to do with the power consumption but this is my 'discovery' phase into what is or isn't possible and why

author: james_s
author_rank: Super Contributor
timestamp: September 26, 2022, 08:04:43 pm
content: This is what engineering is, building solutions by putting together individual subsystems and components based on accumulated knowledge. You build an electronic circuit the same way you build something like a house for example. You start with the foundation, then you build the floor, then you build and erect the walls and so on. You know you'll need windows, and doors and you know the basic rooms like a kitchen, bathroom, bedroom, etc and you decide how many, how large and where to put them. Then the plumbing and electrical, then the interior furnishings. Start with an overall vision, then break it down into subsections, then design each subsection. For example if I'm designing a widget I will start by defining what the widget is, what it's supposed to do, and any other requirements. Then I might start by selecting a microcontroller that I think will be adequate for the task, then I place the stuff I know it will need like power supply decoupling and a clock source, then I work on the power supply block, then whatever peripherals it needs to control and interface with the outside world. Many of these subsections will be similar to what I have used in other designs. Others will be based on concepts I have learned or parts I will fine by searching for components meant to perform a specific task, say controlling a stepper motor, making noises or displaying text on a grid of LEDs.

author: MrAl
author_rank: Super Contributor
timestamp: September 26, 2022, 09:55:36 pm
content: Quote from: PR1OR on September 26, 2022, 10:01:34 amHello,Before you can design anything you first need to master analysis. You basically learn to analyze the crap out of everything under the sun, then you can start to design.The reason for this is you need to gain experience on what is good practice and what works and what doesnt work, and what lasts long and what doesnt, and how to get signals to do what you want them to do, and actuators to do what you want them to do. So it takes time to learn how to design you dont just start designing stuff.Sorry about that, but that's the way a lot of things are. You learn a lot of stuff then you can start thinking about how to create new things that maybe nobody else ever did or just repeat some designs that have already been done.So if you have the time you can learn, but if you are in a hurry you are better off buying some ready made solution.

author: EPAIII
author_rank: Super Contributor
timestamp: September 27, 2022, 06:15:14 am
content: How do I say this?Start by making a list of the things you want this circuit to do. Be specific. Not just a port for this and a port for that, but specifically what those ports connect to and what they do. How fast? What signals? What feedback? Signal levels. Timing. Specifics. How do the tasks on the list interact with each other? Does it need operator control? How? Probably more questions on EACH and EVERY function on the list.Then start with ONE of the items on that list. Perhaps the one that looks like the most central. One that others may lean on (share the functions of) but which does not lean on any others. In other words, one that can stand alone.Now, do some reading. How do others design circuits for this function? What chips do they use? Can you find any examples (schematics) of the circuits they used? Are there any chips that are designed to perform part or all of the needed processing? Download the spec. sheets for those chips. Look for application notes on designing with those chips. They will have suggested schematics with component values already in them. No joke, that is how many devices are designed: JUST COPY THE APPLICATION NOTES. OK, modify them as needed. But a lot is just copying. The engineers who designed the chips did the hard part. Build this part of your device on a breadboard. This allows you to change things as problems become apparent. And test it to see if it does what you want.OK, now after a month or two of work if you are lucky, you have ONE function of the circuit working. Now repeat the process for the next item on your list. And integrate it with the first circuit. And test them together. Perhaps another month.And then add the third item from your list. Repeat as needed until you have a working device on the breadboard.Now you need to design the PCB. You will need a program for that. It will develop what are called the gerber files. They are computer files that describe the features of the PCB. These are sent to a PCB fabricator who makes the board. This can be a few days or a few weeks, depending on things like board complexity and price.When you get the PCB back, you need to assemble the parts on it. And test it. If it works, good. If there are problems, back to the design process to resolve them.

author: PR1OR
author_rank: Newbie
timestamp: September 27, 2022, 07:49:44 am
content: Thanks everyone for your comments i will be using them all to help me in this process! as i imagine it would be a long task but this isn't about a 'quick fix' I'm looking forward to learning which is always a good start hahaThanks again for all your help

author: MrAl
author_rank: Super Contributor
timestamp: September 27, 2022, 01:51:32 pm
content: Quote from: PR1OR on September 27, 2022, 07:49:44 amHi,Learn Ohm's Law, then go from there.

author: rstofer
author_rank: Super Contributor
timestamp: September 27, 2022, 03:10:51 pm
content: Quote from: PR1OR on September 26, 2022, 04:41:12 pmIt does sound like a USB hub. This one meets a couple of the requirementshttps://www.amazon.com/dp/B096KHCSRK?pd_rd_i=B096KHCSRKThese little adapters convert USB-A to USB-Chttps://www.amazon.com/dp/B085VT1VJTYou can tear it apart to find out which proprietary chipset they are using. You might not be able to buy the chips but it will be interesting to see.If you want the fastest USB datarate (and you probably do), the PCB layout alone is likely a post-graduate project.The Microsoft Surface devices have a docking station that does a lot of this stuff but it is pretty much tied to the Surface in that a proprietary cable connection is used at the tablet end. And it's nowhere near meeting the connectivity requirements.

author: Bud
author_rank: Super Contributor
timestamp: September 27, 2022, 05:15:32 pm
content: Do you already know how to write code for USB and HDMI?

author: Terry Bites
author_rank: Super Contributor
timestamp: September 27, 2022, 05:52:31 pm
content: It’s very hard to say in this specific instance. I'm guessing you want to set up motor control parameters, position sensors, current limiting etc.If you have a specific query I'm sure one of us will help.Experience counts, you don't need a formal education. In the world of linear, power and control ics, most manufactures will give you nice simple design equations and calculator tools. Look up the data sheets for your devices. See reference designs they provide. Its made as easy as possible so they can flog their product to you.Read Horowitz and Hill from cover to cover a few times. You'll wise up soon enough (with no hard maths). Its online as a pdf for free. But its best to buy the book, the real thing not a cheap knock off. Put it next to your preferred book of God.Learn some basic analog and discrete logic, then you're ready to interface micros to the outer world.

author: james_s
author_rank: Super Contributor
timestamp: September 27, 2022, 08:16:03 pm
content: I don't want to discourage you, but it sounds like you are a beginner and the project you want to build is quite advanced. You might want to tackle a few simpler more beginner friendly projects before taking on something this complex. Become familiar with the basic building blocks, PCB layout, software coding, debugging, etc and go from there.

author: magic
author_rank: Super Contributor
timestamp: September 28, 2022, 09:29:59 am
content: Quote from: PR1OR on September 26, 2022, 04:41:12 pmI suppose you might be able to assemble something from off the shelf PCBs and cables (USB C hub, HDMI converters) stuffed into a custom enclosure. But designing boards for USB 3.0 and HDMI signals sounds like quite a nightmare. You may even have difficulties buying any sort of HDMI chips in the first place.