What's the difference between a relaxation oscillator made with a DIAC or a Shockley diode?

Thread Starter

lmarcg

Joined May 9, 2020
9
I found both circuit diagrams and their explanations and they look basically the same to me, I don't know if it has to do with the waveform of the output signal but i can't find other differences.
Thanks
 

KeithWalker

Joined Jul 10, 2017
895
A Shockley diode is a four layer (P-N-P-N) device. It conducts when it is forward biased and stops conducting when it is reverse biased. The major difference from conventional diode is that a Shockley diode does not start conducting until the forward voltage exceeds break-over voltage.
A DIAC acts like two Shockley diodes connected in parallel with one being reversed. It is for AC and has the same characteristics for both directions of voltage.
Regards,
Keith
 

Bordodynov

Joined May 20, 2015
2,604
A Shockley diode is a four layer (P-N-P-N) device. It conducts when it is forward biased and stops conducting when it is reverse biased. The major difference from conventional diode is that a Shockley diode does not start conducting until the forward voltage exceeds break-over voltage.
A DIAC acts like two Shockley diodes connected in parallel with one being reversed. It is for AC and has the same characteristics for both directions of voltage.
Regards,
Keith
The DIAC has a very different structure. It has the structure of a symmetric NPN transistor. Its operation is based on avalanche breakdown mode. I made my model based on all this. This model reflects the work of the real DIAC quite accurately.
https://www.mikrocontroller.net/topic/403520Test3.pngTest1.png
 

Thread Starter

lmarcg

Joined May 9, 2020
9
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