Electronics > Beginners
How woud an experienced person "know" how to build the circuit?
Raj:
Well.
I have to say,these days ,there's no fun in making electronics.Computer does most of the stuff for you and the stuff you do these days is just buy parts and get them together on a board and program it.
Back in the analogue and semi digital days, You would have to spend weeks diagnosing and fixing problems and since every device was a a different thing unlike today's smartphone which is literally everything fitted into a single unit, the demand for electronics engineers was pretty high.These days ,its more like either you are soc making Phd guy or nothing.
Now people like us have to spend more time thinking about how we can create new kinds of bulls#!ts like dongles,supporting peripherals that no one really needs (like gaming gear),internet of things,blockchains etc just t get a little bit of money from consumers.\
Either that,or you work in the industry of making industrial gear/research gear.
Beamin:
--- Quote from: german77 on June 27, 2018, 01:48:47 am ---
A good example should be the microSupply that Dave made. You start from a small and simple circuit then start adding complexity until everything works as you like.
--- End quote ---
Episode # 221 lab power supply?
Does taking an ATX supply and adding a 5W resistor count? It has negative voltages and its free!
Can you take multiple ATX power supplies and put them in parallel to make more current? Or is the power supplie's overload circuitry too complex or finicky to do this?
I have built one power supply using a LM part but there wasn't so much to figure that out. I did figure out why the bridge rectifier connects the - sides to the + out though.
While on subject how can you send logic level signals from an arduino to another device (like a relay board with it's own power supply and MCU) when they don't share a common ground? I thought they would have to be joined together or use the same power supply to do this. Can you really just send one +5V lead to anothers I/O and have it work? I see things that look like this but it doesn'tmake sense like connecting one side of a battery.
T3sl4co1l:
FWIW:
Notice that design works in permutation space. That is:
1. We have some variable set of components.
2. Components have pins.
3. The list of connections between pins goes potentially as (pins)! (that's the factorial operator). In a real design, the connections will be sparse, so the size of the space is on the order of, say, 4 choose 100 (that's the 'choose' operator).
Needless to say, the space is large, so you cannot memorize solutions.
That's fortunate for us engineers, who get paid to solve for points in that space. ;D
We of course narrow down that space considerably, by applying electrical rules (any number of inputs can be connected together, and must connect to only one output; outputs cannot connect together), and using building blocks (amps, gates, current and voltage sources and sinks, switches, filters, etc.) to bring order to the mess (say, reducing a problem of 4 choose 100, to more like 3 choose 20 -- which is still pretty big to attack by brute force, mind you).
BTW, a "space" is a set of coordinates over some range. A linear space might be, for example, an array of numbers. 3D space is defined by three axes, numbered over +/-infinity. A permutation space is more specialized, but nonetheless is still just a set of coordinates. If you assign a numbered net to each pin, then all pins that have the same number are connected together on that same net; if different pins connect to that net (even if it's the same number of pins), it's a different circuit. So, different permutations are different circuits, and we have a permutation space. A permutation space is different because it's exclusive: you can't have one pin connecting to two nets at the same time, that's silly, it's just one net all shorted together. That just reduces to a simpler case.
So, any design approaches, algorithms, compiler designs, all that stuff -- anything that applies to a permutation space, can potentially apply to electronic design.
I don't know if that helps, but there's the joke about how mathematicians solve problems. You see, they never actually solve any problems, they just restate the problem in terms of some other already-solved problem, and they're done. ;D
Tim
jmelson:
--- Quote from: Beamin on June 27, 2018, 01:12:21 am ---When learning in school do they teach you a whole bunch of circuits or do they tech you the parts in such detail that the circuits just become an exercise of the mind vs recalling a memory?
--- End quote ---
In EE school, they mostly teach you how to ANALYZE circuits. This is a mostly "forward" process, reducing loops and nodes to simultaneous linear equations, reducing them and then solving them. This is how circuit simulator programs work, This is fairly easily taught, it is mostly mathematics. Coming up with circuits is a lot harder, but without analysis, you are just blind. With analysis, you can select likely generic circuits, write an equation for the generic response, and then figure out the component values to get the specific response (gain, frequency response, etc.) you need. Then, stack these circuits together to get the complete function you need. There are "cookbooks" of useful circuits that can be used as a starting point.
Jon
Buriedcode:
--- Quote from: Beamin on July 20, 2018, 07:25:07 pm ---While on subject how can you send logic level signals from an arduino to another device (like a relay board with it's own power supply and MCU) when they don't share a common ground? I thought they would have to be joined together or use the same power supply to do this. Can you really just send one +5V lead to anothers I/O and have it work? I see things that look like this but it doesn'tmake sense like connecting one side of a battery.
--- End quote ---
At the risk of patronizing you by going back to basics, you need need a potential difference (voltage) for current to flow. Often circuits share a common ground as the 0V reference, but you could also connect the 5V line instead. This would mean the grounds of the two connected devices are at different potential(voltage) and all signals are now referenced to the 5V line. So if the signals are pulled to 0V from the transmitter (say an Arduino) then there will be ~-5V difference between the receivers reference, and the signal. If the receiver had PNP inputs - this would in fact be the only way to send it a signal.
Often relay boards have opto-islators - so require current to drive the internal LED for it to switch the relays - which themselves are powered by a separate power supply. You could hook all the 0V (grounds) together, and use positive voltage signals.. OR.. connect all the LED anodes together, and use your signals for the cathodes. Of course that way the signal is inverted - it is active low, 0V turns on the relay.
The LED in the optoisolator doesn't care about other voltage references... you could hook up its cathode to 1000V and its anode to 1005V (via current limiting resistor!) and it still see's 5V. Voltage is always relative, it is a "potential difference".
If you're talking about sending a signal with a single wire, then it can be done.. https://en.wikipedia.org/wiki/Single-wire_transmission_line
With ground (literally) reference: https://en.wikipedia.org/wiki/Single-wire_earth_return
About experience with circuits - my university covered a lot but wasn't particularly practical, I learnt far more the year after I graduated, learning different areas as and when I needed to know about them. Essentially in a modular fashion (which is pretty much the basis of electronics, and is why such technology is far easier to understand than nature - it was created in layers and blocks rather than co-evolved).
I don't believe someone *must* know everything about Fourier analysis and filters before even attempting to design a filter, or know how to design a Zeta converter from scratch before using SMPS devices. We live in a golden age where components are cheap, many subcircuits are available in modules, where some of the hard work is done for you, and the internet provides FREE information about pretty much anything. Most software (calculators, PCB design, simulators both analogue and digital etc..) is either free or as limited freeware.
If you have a problem than can be solved by electronics, then first see how others have done it, and ask yourself why they did it that way. Then brainstorm your own methods and evaluation the pro's cons of each - engineering is all about compromise and a balance among many factors. Flow or block diagrams help, which can then be broken down into more specific terms, then you can work on each part individually (sub circuits), start hooking modules up all the while testing and adjusting. I don't believe I, or anyone else, gets formal training on "how to design a circuit" as its too vague, its mostly just common sense and experience.
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