You're welcome! I'm always happy when my videos are helpful :-)

You're welcome! TRIACs are quite old school devices. So I guess the engineers at the companies that still make them assume everybody knows how the parameters are tested. Regarding "nobody else did on KZfaq": Again, TRIACs are old school 😅

Thanks!

Thank you very much for the praise!

Thank you so much for the praise!

1988_Motorola_Thyristor_Device_Data

@@ilyaw124 Great reference! Thanks!

Thanks for info :-)

You are very welcome!

Thanks for the praise! I'm always happy when people get something out of my videos.

Thanks for the feedback! Indeed, "potty" was an unintentional mishap :-) "Potentiometer" means the same in English and German. But the abbreviation in German is "Poti", not just "pot" like in English. So I used the German abbreviation while speaking English and it obviously sounds like "potty" - my bad ;-) I'm always torn between cutting the material I've filmed into several smaller videos and publishing it in a single one. Usually I'm publishing it in a single one, because somehow I feel "cheap" stretching the material over several videos. My reasoning is that people can always watch them in several portions - as you did. But I'm still learning ;-) BTW: The next part (mostly theory about limiting parameters) will be out the 31st of March (already filmed it, needs to be cut) and the third an last part (practical considerations) on the 14th of April (currently filming it). And both will be about 45 minutes long again ;-)

You're very welcome!

You're very welcome!

Thank you very much!

Thanks for the praise - and you're welcome! If I remember it right the other two parts are a little bit more taxing ... you'll see.

@@robertssmorgasbord part II was very clear too, just finished watching. I have to datasheets at hand and try to compare 2 Triacs, BT139-600 and BTB10-600. I am analyzing a circuit where a diac is controlling the gate. Your explanation is very helpful for that. Do you talk about a diac in relation to the triac as well in part III?

@@MarcelHuguenin Yes, I briefly discuss the use of a DIAC in the third part. However, on the oscilloscope I just demonstrate the effect of the RC element at the gate of the TRIAC without a DIAC (didn't have one handy when I filmed these videos).

Robert's Smorgasbord I saw it. Your explanation was very helpful. I build the motorcontroller to analyze in the Falstad simulator and now the curves make sense so I understand what’s happening. I can now make changes so I can safely breadboard test with lower voltages (original is mains 230VAC)

@@MarcelHuguenin Happy you got something out of these videos :-)

Thanks for the praise! And you're welcome!

Thanks for the praise! The reason I did this series was that I wanted to use a TRIAC in a project. And you're right. The information about TRIACs on the internet is somewhat incomplete and sometimes outright wrong. So I actually got my textbooks from school/university out and brushed up on that subject. And while I was at it, why not make some videos. It was much more fun that way. Unfortunately I only had to switch a resistive load in my project. So there was no need for a snubber network. But rest assured, if I have a project involving TRIACs and a inductive loads, I'll make a in-depth tutorial about snubber networks.

Thanks for the info! Just love the PUT! If I got it right its like a DIAC for DC where you can set the breakover voltage through a third pin - ingenious! DigiKey lists besides the 2N6027/8 one more active type: CMPP6028TR. It comes in a SOT package for those modern SMD PCBs. So I guess somebody is still using PUTs in their products/designs. I actually did learn about the SCS (German Thyristor-Tetrode :-) ) back in school (I probably learned about the PUT too, but I forgot everything about them - so thanks again): An SCR you can turn off - what's not to like.

You're welcome 🙂 I also provided you a link to some article regarding that resistor calculation you were searching for in a reply to your other comment. Anyway, here it is again: electronics.stackexchange.com/questions/248743/how-is-the-gate-trigger-resistor-value-calculated-for-a-triac

Thanks for the praise! And no, you cannot switch off a TRIAC as long as there's current flowing through the terminals. It doesn't matter what you do with the gate. TRIACs are really made for switching AC.

You're welcome! Indeed, you'll need another optocoupler without zero-cross detection (e.g. MOC3021/MOC3022/MOC3023). And you'll also need to do the zero-cross detection by yourself then. This is often accomplished by another optocoupler (LED - with some more components of course - on the AC mains side).

Yes, indeed. In most AC TRIAC circuits the gate voltage (measured relative to MT1) does change its polarity. That's the wonderful magic of TRIACS, you can switch them on with a positive OR negative gate voltage (current).

There's no thing like a stupid question 😉 All probes were referenced (ground connect to) MT1.

To be honest, I was surprise and a little shocked that this obviously wrong "two SCR analogy" is so widespread on the internet. My textbooks from 1980 got it right (though I have a book "Amateur Electronics" from 1976 that also talks about "two antiparallel Thyristors"). Anyway, you're most welcome! Best Regards from Germany, Robert

@@robertssmorgasbord hai Whether the triac part of this circuit is perfectly designed or not? www.electronicsforu.com/electronics-projects/sunset-lamp 1. Will the triac switch symmetrically for both half cycles of ac? 2. Will the triac start conducting exactly from zero of ac supply (both half cycles) 3. Will the circuit produce harmonics /EMI back to power line for load I am using ? (up to 20 w led lamp) So as to consider it as good alternative for relay ? Relay circuit require more power than triac arrangement that Is I am considering triac and the whole arrangement can be housed inside a lamp holder. Your suggestions please

@@jijeshkorothpoyil2697 To answer your questions: 1. Yes, the TRIAC will switch both halve waves through. As soon as pin 3 of the 555 goes to VCC there's a voltage difference between gate and terminal 1 and the TRIAC is triggered. It doesn't matter which polarity that voltage difference has. 2. When pin 3 of the 555 goes to VCC the TRIAC is triggered at an random point of that very first half wave (there's no zero cross detection in that circuit). Afterwards consecutive halve waves are let through completely. 3. There might be a spike during that first half wave, but otherwise the circuit itself shouldn't produce any interference. I think it's a nice circuit and certainly more elegant than using a relay.

@@robertssmorgasbord Some more clarification please ....... BT 136 600D datasheet says in It's static characteristics (@ Vd= 12V / It =0.1A) that typical gate current for triggering for T2positive ,G positive =2mA T2 negative, G positive=5 mA WHICH IS ........MY CASE Please say 1. can u say is there any " optimum range" of gate current that should be "ensured always " for perfect operation of triac as a switch in my circuit? (Maximum allowed gate current as per datasheet is 5mA and 10mA respectively for my circuit's working quadrants.) OR How to choose gate resistor value in my cicuit? Is 100 ohms correct? My circuit's capacitive power supply can provide 3.5 mA per 100nF in halfwave configuration and 7mA per 100nF in fullwave configuration So as per existing design, it can give maximum around 6 or 7 milli amps. Shall I redesign the power supply? 3 .Is it advisable to put a diode at the 555 output? 4. Is the capacitor at gate is necessary? My circuit triggers ON for "some time" and comes OFF when even other farthest switches in my house is operated with small loads Also some times triggers OFF for "some time" then come ON . When it is ON while operating other switches in my home. (Power line switching noise??) I am thinking to employ fullwave rectification for for isolating the 555 section from neutral Will it help to avoid unwanted triggering due to supply mains line switching noise?( I think It is mostly 555 IC triggering at 1/3 VCC and 2/3VCC levels as the noise voltage affects the trigger input hopefully as neutral is directly connected to its negative. And not a dv/dt triggering Because triac keeps ON for "some time " and The switching noise turns OFF the triac for "some time" when it is ON also The "some time" may be the LDR Response time when light is removed because there is some light feed back happening which is unavoidable as per my scenario. I already put 1n4007 diodes at 555 output just before triac gate and in the negative line to 555 just after triac MT1 .

@@jijeshkorothpoyil2697 Here we go: 1. There is no "optimum range" for the trigger current I(GT). To ensure triggering the trigger current should be at least I(GT) Max times the temperature factor given in fig. 7 of the datasheet (more trigger current is needed the colder the TRIAC is). In your case minimum trigger current of 15mA should do the job. Note: I(GT) Max is not the maximum trigger current the TRIAC can survive, but the maximum current that is needed to trigger the TRIAC. According to the circuit description the NE555 is operated at 15V (you should check that!), so the 100Ohm Gate resistor will deliver 150mA to the TRIAC, which is an absolute overkill and probably drags the circuits supply voltage down. A 15V / 15mA = 1KOhm resistor should be more appropriate there. Note: if the circuit really operates at 15V the (red?) LED would be fried at about (15V - 2V) / 100Ohm = 130mA. So something is not adding up here ... 3. No, you don't need any diode at the NE555's output. 4. I think the capacitor C2 is unnecessary. In fact it delays the triggering of the TRIAC (RC element with R2). I would remove it. To avoid any noise triggering the circuit I would place a small capacitor between pin 2&6 of the NE555 and ground, say 10nF or 100nF. Generally I think the currents drawn through R2 (gate) and R1 (LED) are far too high for that little capacitive dropper power supply.

With a given load, you can't really do anything about the losses between MT2 and MT1. So the only losses you can minimize are actually the gate losses (G, MT1). So to answer your question - its 1: Pulse the gate as short as possible and with a current as low as possible for latching, while there's already enough load to keep the TRIAC latched.

@@robertssmorgasbord You can pick a different triac, with lower on-resistance, right? Which chart or parameter indicates that?

@@johnaweiss Well, you can always pick a TRIAC with a lower on-state voltage. I talk about the on-state voltage in part 2 ( kzfaq.info/get/bejne/rcxiYLZ2rqnFnYU.html ). However, since the on-state voltage is basically the result of the current passing through two "diodes", you will be hard pressed to find TRIACs with significantly lower on-state voltages. If your willing to spend 150 buck you can get something with 0.95V at 100A @25°C ( www.littelfuse.com/media?resourcetype=datasheets&itemid=5970e031-f835-4fa8-b6cb-72c479ff02a5&filename=littelfuse-power-semiconductors-mcma650mt1400nkd-datasheet ).

@@robertssmorgasbord isn't drop different than resistance?

@@johnaweiss Yes, it is different. the diode(s) drop of a TRIAC (on-state voltage) does NOT increase linear with current, like a resistance would do (V = R x I). That's why they provide you (usually) with a diagram of the on-state voltage (voltage vs. current at different temperatures).

Could you somehow upload the circuit diagram (on your channel, Google Drive etc.)?

@@robertssmorgasbord drive.google.com/file/d/1WK23jqK3fFo7mhOSXQWDCWBY8SsRrtMQ/view?usp=drivesdk

@@shadowhunterxxx5891 You'll have to give me access to that file ;-) I've requested it via Google Drive and you should have a message in Google Drive. Alternatively give anybody with the link access to the file.

@@robertssmorgasbord i shared a photo of circuit schematic.there is no request on my Google Drive but its shared

@@shadowhunterxxx5891 I was able to to download the picture now :-) I'm assuming "in" is connected to AC mains and "out" to the light bulb or whatever you're dimming ... Well, your light bulb, respectively, your circuit is at the wrong position! The whole dimmer circuit has to be in series (!) with the light bulb. See electronics.stackexchange.com/questions/206160/light-dimming-regulator-circuit for example. And the reason your pot sparks is, that it's directly connected via the capacitor between live and neutral ;-)

The DIAC is mainly used in the classic analog TRIAC phase control circuit. There an RC element is phase shifting the trigger voltage for the TRIAC, and the DIAC further delays the triggering of the TRIAC, respectively, increases that phase shift even more. See also the third part of this series: kzfaq.info/get/bejne/oNCEpZp1qZjTpXk.html Of course you can use an MCU in conjunction with some zero cross detection to control the TRIAC directly. No need for a DIAC there.

@@robertssmorgasbord Can you make a video in explaining how AC products such as AC light bulbs, AC fans, AC heavy duty motors, AC pumps, AC heaters and etc can be controlled using an Arduino, ESP8266 or any common microcontroller? There is no one on the internet or KZfaq explaining valid information how AC products can be controlled using a microcontroller with the help of a zero cross detection and Triac using parts from raw materials. Everyone uses an optocoupler which has Triac switching built in. Is it possible you can show how to make a Triac driver using raw materials and not bought from commercial stuff? I can’t find any information on the internet on how to make a Triac driver from raw materials. Thanks.

@@ShopperPlug Well, to be hones I have made such a video myself: "Switching AC with Triacs and Zero Crossing Triac Output Optocouplers" kzfaq.info/get/bejne/qLKgedeExt--Y4U.html :-) Anyway, I usually only do tutorials about stuff I intend to use in my projects. And mains AC phase control with a MCU is not on my platter right now. But you'll never know ;-) Meanwhile you might find this interesting: www-user.tu-chemnitz.de/~heha/Mikrocontroller/Triac8/index.en.htm It's a project (not mine) that does everything with just an MCU, TRIACs, diodes, resistors, capacitors and inductors (if you ignore the optocoupler for the DMX control line).

@@robertssmorgasbord do you have WhatsApp or Viber, would like to chat with you about Triac driver. You have knowledge that I can learn from.

@@ShopperPlug I don't have neither WhatsApp nor Viper, or Signal or any other messenger for that matter - I'm kinda old fashioned ;-) Anyway, for privacy reasons I don't share contact information here on KZfaq. As of now I'm not a professional KZfaqr, this is just a hobby for me. Thank you for your understanding!