i know there all the resistors and transistors but how do i tell what they are and what else is on there. also can i use just an random circuit board for anything or are they made special for certain things.

A fuse is a device designed to break a circuit, usually by melting when the current exceeds a certain value. Fuses are widely used in electronic equipment, but have been replaced by circuit breakers in household wiring. In the "old days" people would sometimes replace a blown fuse with a penny, which happened to be the same size as a fuse. Was this a safe practice? Why

High-voltage power supplies are sometimes designed to have a rather large internal resistance as a safety precaution. Why is such a power supply with a large internal resistance safer than one with the same voltage, but lower internal resistance?

Can all combinations of resistors be reduced to series and parallel combinations?

Old-time Christmas tree lights had the property that, when one bulb burned out, all the lights went out. How are these lights connected, in series or in parallel? How could you rewire them to prevent all the lights from going out when one of them burned out?

I’m going to make this circuit (http://forum.allaboutcircuits.com/attachment.php?attachmentid=13352&d=1257607202) ( A LED lamp using Phone line power, this was found from internet). In this circuit, the well-known LM317T volt regulator is used to control the voltage. However I have a doubt of arrangement of these components. As per the data sheet, In order to control voltage, two resistors need to be used as my 2nd pic(http://forum.allaboutcircuits.com/attachment.php?attachmentid=13351&d=1257607202). So please tell me whether this is correct….. (I’m not an electronic expert..:-( )

I have small battery powered electronic toy that makes sound. I would like to amplify the sound to make it louder. I have a very basic knowledge of electronics, so I could add small capacitors or resistors to some wires, but anything involving complicated circuit boards or actually rewiring the toy itself are pretty much out of the question. Thanks…

I want a user friendly software that uses a drag and drop approach to design a electronic circuit, measure current or voltage between any points, some basic components in it like resistors, transistors, capacitors etc… Do you know any software like that?
Sheldon, i wanted a drag and drop type software. not a programming software..

and Blackstreet you dipshit, your software doesnt allow me to test the circuit.. it allows me only to build it and chuck it out of window.
All these dipshits got the answer wrong.
All of these are only drawing software. But i wanted a software with which you can test the actual circuit.

I have three laser diodes connected in series.
They require 2.5V and 120-130mA to operate.
I have 8 available batteries, each 1.2V and 900mA.
I want to create a circuit using these batteries and laser diodes, without overloading the laser diodes, so resistors need to be added to the circuit.
What circuit do I require for this to work? Please include resistor
values
Thank you!

/——-BAT———DIO–DIO–DIO—/
/
/———[ R? ]————————/

What is the full name of an Element starting with Q?
On a circuit board there are labels. For example for resistors it is "R", for diode "D", for capacitor "C" what is "Q" for?

tcu in a honda accord and it has 2 resistors burnt black, how do i find out what kind they are ?

I am requesting support from someone who knows electronic power circuits. I have an AC adapter, input 120VAC, two outputs: 32VDC & 16VDC. I connect a voltmeter to either output and when I plug it in, output is instantly correct but then slowly reduces to zero asymptotically. It will not deliver any output again until is it unplugged and plugged it again. It then jumps to the correct output, then repeats the slow reduction to zero. I know enough to suspect that the slow fade-out is a DC capacitor discharging but beyond that I don’t know what components to check or how (other than one-way continuity of diodes, resistance of resistors, etc. I have completely eliminated the possibility that it’s a faulty connection or power cord.

I’m learning programming for the first time (starting with C for beginner) but I first I want to understand exactly what happens when I type the key, let’s say "b" on my keyboard and seeing letter "b" appear on a notepad for instance.

My guess is this and I’m not sure to what extent it is correct:

First, a computer is, physically speaking, nothing but electricity and circuitry (matter; electronic components such as resistors, capacitors etc and electrical power which comes from the battery/wall and finally the way all these are connected to one another)

1. The keyboard, being an electronic device, needs electricity in order to work so it is powered by the computer through the USB port.

2. By pressing any key ("be" in our case), I’m actually closing a circuit which makes some current/voltage flow (high for 1 and low for 0)

3. Some programs (Operating system which then communicates to notepad God knows how) convert this series of high’s and low’s or 0’s and 1’s into what I see on my screen as letter "b" on the notepad.

Am I close to the reality of computing?

I mean how does the computer know that I have actually pressed the key "b" on the keyboard and not "a", does every key send some sort of special current or something? This part I need clarifying the most!

Does this have anything to do with "Hex"?

Thank you.
where does the processor come into play in all of this? my processor is 2 GHz, what does this mean in terms of typing and seeing something on the screen?