Why are Diodes needed?

[thescreensavers]

I suppose there is a reason but why?

From what I read a Diode is a one way valve for electricity. Why not just hardwire it in?

 

[Modelworks]

Transistors

 

[thescreensavers]

oh I see a Rectifier diode changes the current from AC to DC? Is that its only job?

 

[Zenmervolt]

Huh? Why not just hardwire what in? The diode? If that's what you mean then what you've said doesn't make any sense because even if they're soldered in, they're still diodes.

Or are you trying to ask why are diode replaceable in many situations? That's simply a manufacturing choice.

Or if you're actually wondering what diodes are used for, the principle example is rectification where AC is converted to DC. Other uses are radio demodulation, overvoltage protection, and even for ensuring that in a UPS power is only drawn from the battery when mains power gets disconnected.

ZV

 

[thescreensavers]

^ I was just confused as I read Diodes are a one way valve for electrcity. When I meant hardwire, its just to skip diode all together and just put a direct connection.

But now that I see they convert AC to DC. So thats the job they do.

Thanks for the replies.

 

[Matthiasa]

They can also be used to make logic circuits.

 

[Leros]

Diodes have a lot of uses. Off the top of my head:

Diodes are used in rectifiers to convert AC to DC.

Diodes are attached to loads with high inductance (such as motors) to prevent back EMF from destroying the circuit.

They can be used for simple logic circuits.

If I recall, diodes can be used to sense temperature.

Not to mention, light emitting diodes can create and sense light at specific frequencies.

 

[Born2bwire]

The can also be used as voltage regulators.

 

[olds]

OP, do you know what "AC" means? Do you know what a "cycle" is?

 

[frostedflakes]

It's just a device that passes current in one direction but not the other (assuming you don't exceed the breakdown voltage of the diode). Has all kinds of uses: Rectification, simple voltage regulation (using Zener diodes), isolation of transistors in integrated circuits, etc.

 

[dawp]

a zener diode is quite the interesting device.

 

[esun]

They function like water valves or heart valves (ones that only allow liquid to flow in one direction while blocking the flow in the opposite direction). You can't "hard wire" something like that in a circuit any more than you can in a water pipe: you need some type of flow control and a diode does that.

 

[Net]

manipulate the flow of current.

one of many tools to use to control current in your design.

for an analogy: assuming a drawing is a collection of shapes, why is a triangle needed in a drawing?

a more general question would be why do you need to manipulate the flow of current.

here is a brief intro: http://books.google.com/books?id=0y...=why%20manipulate flow of current&f=false

 

[PottedMeat]

^ I was just confused as I read Diodes are a one way valve for electrcity. When I meant hardwire, its just to skip diode all together and just put a direct connection.

But now that I see they convert AC to DC. So thats the job they do.

Thanks for the replies.

they do all of the above, but it sounds like you're talking about the input to some device. this may be because some power supply barrel connectors are reverse polarity. a series diode at the power input prevents applying reverse voltage from damaging the device.

 

[WelshBloke]

They function like water valves or heart valves (ones that only allow liquid to flow in one direction while blocking the flow in the opposite direction). You can't "hard wire" something like that in a circuit any more than you can in a water pipe: you need some type of flow control and a diode does that.

Yeah you can, you just need to use a diode. :whiste:

 

[Fenixgoon]

lighting. not sure how you all missed that

 

[LTC8K6]

An "alternator" that doesn't have any diodes was called a generator back in the day. :biggrin:

 

[IndyColtsFan]

^ I was just confused as I read Diodes are a one way valve for electrcity. When I meant hardwire, its just to skip diode all together and just put a direct connection.

That makes no sense. A diode can switch on or off depending on the voltage at its terminal. Engineers don't throw diodes in for the fun of it.

But now that I see they convert AC to DC. So thats the job they do.

Thanks for the replies.

That isn't the only job they do. Have you heard of an LED? What do you think the D might stand for? Your TV remote -- guess what the infrared emitter is?

EDIT: I never realized how much I missed electronics. Maybe I ought to pull out the old breadboard and build some circuits.

 

[marvdmartian]

We need diodes because selfish geeks & nerds generally wouldn't understand it if you called them a "one way, check valve mother f*cker!!!" :sneaky:

 

[MoMeanMugs]

They're only one way within a certain region. They break down past a certain point and current can flow the other way. Depends on how much they were doped during manufacturing. Inject the Boron!

 

[Gibson486]

prevent back feed .

 

[Gibson486]

That makes no sense. A diode can switch on or off depending on the voltage at its terminal. Engineers don't throw diodes in for the fun of it.



That isn't the only job they do. Have you heard of an LED? What do you think the D might stand for? Your TV remote -- guess what the infrared emitter is?

EDIT: I never realized how much I missed electronics. Maybe I ought to pull out the old breadboard and build some circuits.

That is not a diode, but transistor. And yes, LEDs are essentially diodes.

 

[IndyColtsFan]

That is not a diode, but transistor. And yes, LEDs are essentially diodes.

What is a transistor? Infrared? You can also use an infrared diode.

 

[Albatross]

http://www.physorg.com/news/2010-10...s-high-performance-metal-insulator-metal.html
Maybe transistors will be obsolete some day.

 

[PottedMeat]

What is a transistor? Infrared? You can also use an infrared diode.

the remote emitter is an infrared diode, the receiver is a transistor with the base exposed to light.