Discuss Diodes and Thyristors in the Industrial Electrician Talk area at ElectriciansForums.net

C

City

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Hello all,
First post here! I need some help with this one. What's the difference between a thyristor and a diode? They both conduct in one direction, both lack a gate, they all conduct AC, except that diode doesn't have a gate? Is there any other difference? :confused:
Any help would be much appreciated!
 
W

wayne

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  • #2
hi and welcome i learnt about semi conductor devices from a non text book before wikipedia was thought up. now if i need to remember i use wikipedia ,havent i mentioned wikipedia before ? the memory seems to be going perhaps it needs ramming or rebooting ..........wikipedia.
 
C

City

  • Thread Starter Thread Starter
  • #3
I've already scoured the internet for what I could find. Unfortunately however, no article I've read appears to go into detail enough for me to be able to clearly distinguish between the two. Diodes are a type of thyristor, and diodes have 2 terminals as opposed to 3. That's all I've been able to gather from the internet (hyperphysics, wiki) and 2 books I've gone through. SCR's vs diodes, they both seem to be the same thing. Anything at all?
 
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ian.settle1

-
Mentor
Arms
Hello all,
First post here! I need some help with this one. What's the difference between a thyristor and a diode? They both conduct in one direction, both lack a gate, they all conduct AC, except that diode doesn't have a gate? Is there any other difference? :confused:
Any help would be much appreciated!
Do not know where you got your info from but a thyristor does have a gate. :rolleyes:

you need to apply a voltage to it for it to conduct.

A thyristor is also known as a SCR (silicon controlled resistor) used some years ago on speed control on cranes for switching out resistor banks.
 
R

rumrunner

  • Thread Starter Thread Starter
  • #5
I've already scoured the internet for what I could find. Unfortunately however, no article I've read appears to go into detail enough for me to be able to clearly distinguish between the two. Diodes are a type of thyristor, and diodes have 2 terminals as opposed to 3. That's all I've been able to gather from the internet (hyperphysics, wiki) and 2 books I've gone through. SCR's vs diodes, they both seem to be the same thing. Anything at all?
heres the links to what wayne sugested in the first place ,i think there should be enough info ,even for you now:eek:


Diode - Wikipedia, the free encyclopedia

Thyristor - Wikipedia, the free encyclopedia


have fun:)
 
S

Shakey

  • Thread Starter Thread Starter
  • #6
Hello all,
First post here! I need some help with this one. What's the difference between a thyristor and a diode? They both conduct in one direction, both lack a gate, they all conduct AC, except that diode doesn't have a gate? Is there any other difference? :confused:
Any help would be much appreciated!
Basically a diode is rectifier, once it is forward biased, with an anode to cathode voltage of about 0.6 V it will conduct, in one direction only

Think of thyristor as the same thing but with a gate. it still needs a forward bias to work, but only switched in when current is applied to the gate, once triggered it will stay conducting until it is reversed biased, (by putting +ve v on the cathode) or until the forward bias V is removed

It works in a similr way to relay or contactor - switching a high current circuit from small signal

Hve you ever seen a bridge rectifier? This is 4 diodes connected in series parrallel, and will turn an AC supply to a full wave rectified DC output

Well by replacing the output diodes with thyristors, you can 'pulse fire' them on and off to control the level of DC current and voltage output - this is how larger battery chargers work

They use banks of pulse fired thyristors to control motor speed in invertors and soft starters

Does that answer your question?
 
C

City

  • Thread Starter Thread Starter
  • #7
Basically a diode is rectifier, once it is forward biased, with an anode to cathode voltage of about 0.6 V it will conduct, in one direction only

Think of thyristor as the same thing but with a gate. it still needs a forward bias to work, but only switched in when current is applied to the gate, once triggered it will stay conducting until it is reversed biased, (by putting +ve v on the cathode) or until the forward bias V is removed

It works in a similr way to relay or contactor - switching a high current circuit from small signal

Hve you ever seen a bridge rectifier? This is 4 diodes connected in series parrallel, and will turn an AC supply to a full wave rectified DC output

Well by replacing the output diodes with thyristors, you can 'pulse fire' them on and off to control the level of DC current and voltage output - this is how larger battery chargers work

They use banks of pulse fired thyristors to control motor speed in invertors and soft starters

Does that answer your question?
Exremely helpful shakey, thanks alot!
 
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