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-   -   Electrical diagrams 101 ? (http://forums.pelicanparts.com/porsche-911-technical-forum/1074919-electrical-diagrams-101-a.html)

sugarwood 10-05-2020 11:02 AM

Electrical diagrams 101 ?
 
https://learn.sparkfun.com/tutorials/capacitors/all

I've been doing some reading on capacitors, relating to a non-automotive subject. I came across a few basic diagrams and thought it may be worthwhile to take the first step in reading automotive electrical diagrams. Basic electrical troubleshooting is my favorite aspect of automotive DIY. Testing wires for continuity, testing if a switch is good, then testing is power is getting to the motor, applying power directly to a motor to determine if the motor is dead, etc. But, I've never used an electrical diagram.

There may be others who are interested in the next step of reading diagrams.
Is anyone willing to post and explain a very basic electrical diagram relating some some simple aspect of the 911?
Like a window motor, for example

For example,

The ===/+++ thing is a capacitor that can hold a charge.
The long and short lines are the power source battery.
The circles and line are a locking switch
The zigzag lines are a resistor of some sort (LED light, etc)

When the switch is down, the battery loads the capacitor
When the switch is up, the capacitor empties its electrons towards ground.

https://cdn.sparkfun.com/assets/d/2/...e042000002.gif

Trackrash 10-05-2020 11:06 AM

Who knew that motion gifs would run on Pelican.

So now you need to explain all the components and what is happening. I see you have done that.

However the wire from the battery to the cap isn't turning yellow when energized.

theiceman 10-05-2020 11:55 AM

Electrical guys stay quiet, but a good learning opportunity is figuring out why the resistor is there ;)

sugarwood 10-05-2020 01:59 PM

Quote:

Originally Posted by theiceman (Post 11053084)
Electrical guys stay quiet, but a good learning opportunity is figuring out why the resistor is there ;)

It's the thing getting powered, like an LED light ?

timmy2 10-05-2020 02:50 PM

Simple RC circuit, add a 555 timer to make it flash continuously. :)

Walt Fricke 10-05-2020 08:40 PM

CDI is fundamentally sort of like that diagram.

theiceman 10-13-2020 05:58 AM

Quote:

Originally Posted by sugarwood (Post 11053270)
It's the thing getting powered, like an LED light ?

think about ohms law,,, how much current is needed to power an led ... and how much resistance is in an led...

T77911S 10-13-2020 04:27 PM

i work on radar for the FAA.
a CD is very much like the PFN (pulse forming network) In the transmitter.
our new radar is digital, the old one had a vacuum tube that was about 3ft tall.

MBAtarga 10-14-2020 06:12 AM

Quote:

Originally Posted by theiceman (Post 11062946)
think about ohms law,,, how much current is needed to power an led ... and how much resistance is in an led...

E = I / R

As R (resistance) decrease, I (current) goes to infinity where E (Voltage) > 0.
I cheated - 4 years of EE at GT. :)

sugarwood 10-14-2020 02:28 PM

Quote:

Originally Posted by theiceman (Post 11062946)
think about ohms law,,, how much current is needed to power an led ... and how much resistance is in an led...

You sound confused.
Did you read the link?

Quote:

For example, in the circuit below, a battery can be used to induce an electric potential across the capacitor. This will cause equal but opposite charges to build up on each of the plates, until they're so full they repel any more current from flowing. An LED placed in series with the cap could provide a path for the current, and the energy stored in the capacitor could be used to briefly illuminate the LED.
The diagram is of a circuit that powers an LED bulb.
Why does it have a resistor?
B/c that is the thing being powered!
That is the entire point of the stupid circuit. Duh.

MBAtarga 10-15-2020 04:15 AM

Quote:

Originally Posted by sugarwood (Post 11064847)
The diagram is of a circuit that powers an LED bulb.
Why does it have a resistor?
B/c that is the thing being powered!
That is the entire point of the stupid circuit. Duh.

I'm not sure you understand the purpose of the resistor based on that comment.
What is the voltage drop across the LED? What is the current in the wiring assuming the battery is 12V?

Geneman 10-15-2020 10:50 AM

This would be fascinating to hear expanded upon by you electro-jocks. i am SEVERELY electron flow challenged, even though I have been soldering together kits from Radioshack since i was ten or so... but i still bnever understood why the hell your need all these resistors, diodes, caps, even considering a transistor mechanism makers me cringe with horror and results in a blank stare ( even though I am quite efficient at programming CAR-T cells, immunotherapies and Gene jockeying..) ... carry on on pleasse! Frank

theiceman 10-15-2020 11:56 AM

the purpose of the resistor is to limit the current going through the led.. keeps circuit current low.. forward biased diodes have very little resistance and require very little current to light, without the resistor the higher current flow would burn it out .

motorstereo 10-15-2020 12:32 PM

If you're "electrically challenged" like me, pick up Rob Siegel's book "the Hack Mechanic Guide to European Automotive Electrical Systems". It's kind of an idiot's guide to electrics and it covers such rudimentary topics as how relays work, how to test your alternator, how to jump a relay, guide to DIN numbering standards, troubleshooting a circuit etc.

looks like our host even sells it!

MBAtarga 10-15-2020 01:17 PM

Quote:

Originally Posted by theiceman (Post 11065758)
the purpose of the resistor is to limit the current going through the led.. keeps circuit current low.. forward biased diodes have very little resistance and require very little current to light, without the resistor the higher current flow would burn it out .

Yes - and depending on the wire gauge - without that resistor either the wiring or the LED is going to go open circuit. This is basically what a circuit breaker in your house does - limits current flowing through wiring.

john70t 10-15-2020 01:22 PM

Quote:

Originally Posted by theiceman (Post 11053084)
Electrical guys stay quiet, but a good learning opportunity is figuring out why the resistor is there ;)

Good call.
Wouldn't that make the wire the only resistance in the circuit, allowing full current to pass through it?
(aka direct short to ground)

That would last as long as it takes for the wire to melt.
I've seen a battery melt a hole though a dented hood with people sitting on it. Big fountain of sparks.

Crispy crunchy wires isa no good.

mike sampsel 10-15-2020 01:31 PM

but where is the imaginary part of the impedance? :confused:;)

911obgyn 10-15-2020 01:55 PM

It’s the faucet you turn down to limit flow.
Or inline pressure regulator or tiny oriface

ChrisHoover 10-15-2020 02:35 PM

There is no load on the circuit without a resistor. A no load circuit is otherwise known as a short. Changing the value of the resistor will change the brightness of the LED.

70SATMan 10-15-2020 03:08 PM

Technically not true. Even the wire and the LED represent a "load",,,,,

Just not for long, LOL.


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