When I was a telephone engineer, I used diacs as a privacy device where multiple telephones were on the same pstn circuit. Put one in the line path on each telephone. The line voltage across the diac wil be around 50v so you get dial tone when you pick up, the line voltage falls to around 12v but the diac continues to conduct. Anyone else picking up a phone on that circuit gets a dead line because the 12v is below the break over voltage. Simple single component privacy.
@ElectronicsNotes6 ай бұрын
Yes they had a good number of different uses in s variety of circuits.
@clownhands6 ай бұрын
Genius use of a diac!
@jamescollier36 ай бұрын
That's like the most intelligent comment in socal media lol
@rex-up9ln6 ай бұрын
@@jamescollier3cool
@gustavotasquer73895 ай бұрын
Brillant
@headpox58176 ай бұрын
Thank you for this no-nonsense description of a DIAC.
@ElectronicsNotes6 ай бұрын
Glad it was helpful!
@dl52446 ай бұрын
Despite the symbol appearing as two diodes with opposite orientation in parallel, it seems that a DIAC behaves very similar to two Zener diodes in series with opposite orientations. This arrangement of two zeners in series would block current flow in both directions until Vbr+Vf is exceeded, just like a DIAC
@Vincent_Sullivan6 ай бұрын
Not so much... Notice in the DIAC V/I curve shown that when the DIAC breakover voltage is reached the voltage across the DIAC falls to a very low voltage (Vf is much less than Vbo) whereas the arrangement of 2 opposite polarity Zeners in series will clamp the voltage across them to the Zener voltage plus the forward voltage of the conducting diode as you state - so the overall effect in a circuit may be quite different.
@SimEon-jt3sr6 ай бұрын
Was just wondering lol like why block it both ways, the zener make a lot more sense but now the symbol still makes sense
@SimEon-jt3sr6 ай бұрын
@@Vincent_Sullivan Oh..... Well luckily I probably won't ever need to design my own circuit with one...
@deantiquisetnovis6 ай бұрын
Short, crisp, clear. In other words: brilliant!
@ElectronicsNotes6 ай бұрын
I’m really glad you found it useful.
@peterbulanyi17086 ай бұрын
Very nice description of the Diac. I remember seeing these devices on the control terminal of Triacs in simple electric fence energisers when I used to repair them in the early 90s.
@ElectronicsNotes6 ай бұрын
Thank you very much for your comment. Yes, they were very common. I remember them from their use in light dimmers. But the application you found them used in shows how widely they were used.
@louco26 ай бұрын
Learned something new today! Thank you so much for taking the time to do these videos.
@ElectronicsNotes6 ай бұрын
Glad it was helpful! It is so good to hear when someone finds these videos useful.
@stupossibleify5 ай бұрын
Hackaday brought me here, and I'm so glad it did. Thank you.
@ElectronicsNotes5 ай бұрын
I'm really glad you arrived on the channel - please check out some more videos. Thanks for your comment.
@rohnkd4hct2606 ай бұрын
Thanks for the refresher lesson! Electronics School was llllllloooonnnnggg time ago 😆
@ElectronicsNotes6 ай бұрын
You're welcome! Glad you found it useful.
@Necrocidal6 ай бұрын
Really nice and to-the-point, thanks!
@ElectronicsNotes6 ай бұрын
Glad you found the video useful. Thanks for your comment.
@borisj40546 ай бұрын
Very basic but good for beginners
@ElectronicsNotes6 ай бұрын
It is aimed at providing the basics for those who are not familiar with DIACs. I hope you managed to take something away froth e video. Thanks for the comment.
@Doom2pro6 ай бұрын
I always thought of them as a solid state spark gap of sorts.
@xanataph6 ай бұрын
Yeah definitely, or I would also say, like a solid state replacement for a neon bulb in such triggering circuits.
@MrAvant1236 ай бұрын
Also, I would say using a DIAC to switch a Triac cuts right down on the nasty crossing RF interference you get from a raw switched Triac.......
@ElectronicsNotes6 ай бұрын
Indeed it does.
@wisteela6 ай бұрын
I didn't know these existed.
@arthurmoore94886 ай бұрын
Randomly was suggested this video. I have designed a voltage to frequency converter for an isolated high voltage power supply before. They're extremely useful wherever a trigger threshold voltage is needed. Now I'm wondering if I can make a DC mains voltage 555 timer.... On the other hand, Mains AC has such a consistent frequency I could just make a clock.
@SlyerFox6666 ай бұрын
Such a good video, could have mentioned the 5 layer as a SIDACs as that's a component that hardly anyone's heard of. 👍
@ElectronicsNotes6 ай бұрын
Glad you liked the video. Yes, I suppose I could have mentioned the SIDAC but I wanted to focus on the DIAC. Thanks for the idea though - maybe another video sometime.
@arthurmoore94886 ай бұрын
@@ElectronicsNotes Please. I've used DIACs before, but never even heard of a SIDAC.
@ElectronicsNotes6 ай бұрын
@@arthurmoore9488 I thought I had a description of them on my website, but could not find it. However, you can take a look here: en.wikipedia.org/wiki/DIAC#:~:text=A%20silicon%20diode%20for%20alternating,member%20of%20the%20thyristor%20family.
@bretfuzz9256 ай бұрын
I used a SIDACtor to protect the TX side of a DS1 (T1) line interface module from CMOS latch up from transient voltages. Very handy device indeed as it would reset on the zero voltage crossing after a transient event. Much better solution than PTC thermistors.
@SlyerFox6666 ай бұрын
@@bretfuzz925 Well you just taught me a few things there, nice example 👍
@AdrianHiggins836 ай бұрын
Very good explanation
@ElectronicsNotes6 ай бұрын
Thanks for your comment. I really appreciate it.
@s.hutton21006 ай бұрын
Excellent video thank you. Have subscribed. Regards Stephen.
@ElectronicsNotes6 ай бұрын
Glad you liked the video and thanks for subscribing.
@jonathanwilhelm88916 ай бұрын
Very nice video ❤ great work
@ElectronicsNotes6 ай бұрын
Glad you appreciated it. Thanks for the comment.
@maxwang25376 ай бұрын
Short and sweet!
@ElectronicsNotes6 ай бұрын
Hope you found it useful.
@maxwang25376 ай бұрын
@@ElectronicsNotes yes very helpful. Recently I cam across one on a modern sewing machine foot pedal (motor speed controller), which I mistook as a diode.
@MrMulleteer6 ай бұрын
Triac/diac dimmers are getting pretty rare because they cant reliably work with the light loads like leds. IC controlled triacs are becoming the norm.
@ElectronicsNotes6 ай бұрын
Indeed, but the DIACs are still used wit them in some instances and also they can be used for other applications such as transient limiting. But yes, with modern LED lamps which require the cycle to be cut on the trailing edge, the traditional circuits are not as widely used.
@qzorn44406 ай бұрын
very nice. Thanks.
@ElectronicsNotes6 ай бұрын
Most welcome - glad you appreciated it. Thanks for the comment.
@kamalhamdi67396 ай бұрын
Thank you for information khalid Morocco Casablanca
@ElectronicsNotes6 ай бұрын
I’m glad you found the video useful.
@enggdiplomabook70765 ай бұрын
Very nice video❤
@ElectronicsNotes5 ай бұрын
Thank you!
@xDR1TeK6 ай бұрын
I see the KZbin algorithm is working well at last. I liked its suggestion quite well. One question though, seeing how the diac is a diode for ac, but works as two zeners back to back, shouldn't it be called a zener for ac instead? Ziac or something like that? Just wondering. Thank you for the wonderful presentation.
@ElectronicsNotes6 ай бұрын
I love your idea. A DiAC actually works in a different way to two Zeners back to back, in terms of the underlying physics, but it does appear to give a similar effect in the surface. Great idea!!
@peetduplessis77966 ай бұрын
Like your AVO Model 8/9. Still have a 9 Mk II.
@ElectronicsNotes6 ай бұрын
Yes, it’s an AVO 8 and it still works well.
@peetduplessis77966 ай бұрын
Proper equipment that is well cared for will work for many years! @@ElectronicsNotes
@tenlittleindians6 ай бұрын
So how do you test these components when found in a circuit?
@ElectronicsNotes6 ай бұрын
Not easy to test, and especially when in circuit.
@bob_mosavo6 ай бұрын
Thanks 👍
@ElectronicsNotes6 ай бұрын
Thank you too!
@xanataph6 ай бұрын
You see in a lot of older schematics for light dimmers, drill speed controllers etc they used neon bulbs to do a similar job to the DIAC due to their breakdown characteristics. But I would presume the DIAC's characteristics are sharper than that of a neon? (And of course exhibit the breakdown at a lower voltage)
@ElectronicsNotes6 ай бұрын
I confess I've never thought of using a neon, but good point.
@maxwang25376 ай бұрын
2:32 a question here. I suppose what’s shown here is the behaviour of an ideal triac we would expect. How far off are the actual characteristics of a real triac from this?
@maxwang25376 ай бұрын
2:43 I have difficulty understanding triac. Some questions please. Are the two main terminals of a triac symmetric with reference to the gate. In other words, can we apply a trigger voltage between the gate and either terminal 1 or 2 to switch it on? In the schematic here, which voltage is working as the trigger, the voltage across the pot or the cap, or both? Any help is appreciated!
@Accumulator15 ай бұрын
On those light dimmers, what component is likely to fail on them? Would it perhaps be the triac or diac? I have several that stopped working, I like to repair.
@ElectronicsNotes5 ай бұрын
My guess is that kit is most likely the Triac, but I've no great experience on fixing light dimmers.
@henryj.85286 ай бұрын
What was that four-layer device Shockley was always working on?
@ElectronicsNotes6 ай бұрын
He was working on a four layer device, and it probably developed into what we know today as a Thyristor.
@user-lp3cf5yn5b4 ай бұрын
So basically it acts like a wall until the breakdown voltage is exceeded then it conducts like a diode until the voltage drops below breakdown voltage again?
@ElectronicsNotes4 ай бұрын
That is a sort of descriptor it. The characteristic is a little more complicated, but it acts like a “wall” until a break over voltage is reached. Then the voltage falls and slightly rises with increasing current.
@StephanBuchin6 ай бұрын
2:33 Is the conduction waveform presented here corrected by the diac? Because it looks pretty symetrical to me.
@ElectronicsNotes6 ай бұрын
I used the perfectly switched waveform and not one that you might find from a triac on its own. I was trying to illustrate the way the triac controlled the waveform.
@StephanBuchin6 ай бұрын
@@ElectronicsNotes Thank you for answering my stupid question, you relieved my anxiety of not understanding. I remember i was already this tiring when I was a student 🤓
@ElectronicsNotes6 ай бұрын
@@StephanBuchin You question was perfectly valid and not stupid in anyway. We all learn by asking questions, and often the 'stupid' questions are the ones that everyone else wants to ask, but nobody dares. Thank you.
@johnaweiss6 ай бұрын
I wonder if it could be used as a dead-time generator.
@ElectronicsNotes6 ай бұрын
I had never thought of that - may be it could.
@johnaweiss6 ай бұрын
@@ElectronicsNotes i guess maybe you'd have to feed it a sine wave... mains is a sine wave.
@ECHQ235 ай бұрын
you could expand on this and compare to a "modern" bidirectional TVS diode.
@ElectronicsNotes5 ай бұрын
That is certainly a possibility.
@user-xi5oh9yc4c6 ай бұрын
I do not understand how you read that plot at 1:45
@ElectronicsNotes6 ай бұрын
Looking at the top right quarter, imagine the voltage rising and little current is passed, when it reaches its breaker point, the current increases and the voltage across it falls, and then this voltage is increases slightly as the current increases much more.
@billfargo96165 ай бұрын
LEDs are dimmed using pulse width modulation, not voltage control. .
@ElectronicsNotes5 ай бұрын
I wanted to say that the light dimmer I was showing was for incandescent lamps as LEDs use a different approach.
@rickhunt31836 ай бұрын
A diac never met a triac it didn't like.
@stanleybest88336 ай бұрын
Don't advocate dimmer switches. They generate a heap of radio noise.
@alunroberts14396 ай бұрын
Get that AVO on it;s back no one knowing about them stands them up like that
@ElectronicsNotes6 ай бұрын
Indeed you are right - when it is used, it is most certainly on its back, but it lives there when not in use.
@alunroberts14396 ай бұрын
@ElectronicsNotes still never store it like that it not a show pice