Review AC Relay Circuits Optocouplers Triacs

Review of AC SSRs as part of a series on power switching.
www.bristolwatch.com/index.htm

[@a.a.patrick]

great explanation. I tried phase control for motor speed control. I have had issues of resistor burning from current limiting resistor on the A.C side.

[@mohammedal-hababy3616]

we use moc3031 to control the speed of fan and thee output was not stable do you think the delay effects on the output?

[@vizmohanan]

Hello Sir, What's the use of R1 (10K) connected across GATE and GND ? How is the values for R1, R2 and R3 resistors are calculated ? Helpful video BTW. Thanks :)

[@saturn5tony]

Very cool video, thank you for sharing.

[@DanChicheportiche]

Hi, thanks for your video How the triac work to deliver constant voltage on a smart switch without neutral ? (With capacitor on the bulb) Do you have a schematic ?

[@shoppingoneclick2044]

MOC 3041 or 63 with traic are quite old technology. Is there something better solution, available for soild State relay? Traic has good chance of failure. I am looking for some better IC with zero cross detector and with good protection. Please guide me.

[@goutammukerjee6229]

I need a scheme tic circuit for 1/2hp dc230v motor speed regulator

[@michaelomiccioli4646]

Lewis, this was most helpful thank you for the video. I have a question I was going to use a MOC 3031 connected to a an arduino to run a lawn sprinkler. The sprinkler valve is on a 24VAC circuit at about 225 ma. From what I see this should work, can you confirm this? Or is there a better approach? Thanks

[@LewisLoflin]

By it self the MOC3031 won't carry the current.

[@prashkd7684]

While I'd prefer to just buy a random switch SSR relays for my project, comparedd to ZCD SSRs they're so damn expensive (and rare) that I'd rather try my luck with TRIACs. Thanks for such detailed explanation.

[@norbeninternational1274]

Hi Lewis, How do we protect the above TRIAC based circuit from AC short circuit ? Will Snubber circuit work in that case ?

[@LewisLoflin]

A snubber won't help with a short. Use a fuse.

[@Vladviking]

Is the MOC 3043 turning off in AC because of the low spot or reversal of the current? And staying on in DC because there is none? And so these optocouplers would not work in anything other than single phase? Thanks

[@LewisLoflin]

It turn off when the voltage goes to zero.

[@LousyPainter]

In the H1 1CX circuits could you explain how the resistor on the gate works? I don't understand how it can do anything because it's not appearing to complete a circuit. Thanks

[@LewisLoflin]

That controls the gate sensitivity. Without it it turns on all the time. I used 47K myself.

[@ahmedmbarak5146]

Hello Mr Lewis, If i want to control a single phased motor which has three wires. How should i connect the live, neutral and ground?

[@LewisLoflin]

The triac is connected to the "live" the neutral and ground are connected as usual.

[@VasilisKarastergios]

Thanks for making this video very well explained sir, can you make a tutorial about ac/dc relay snubber circuits?

[@wolfgangboettcher3126]

Gleichrichter

[@hectorbarrera9496]

Nice explanation, I have a doubt, for the snubber (5:57), could I use this values for a 0.5 hp @ 4 A pump water? Hope you could help me. Thank you

[@shoppingoneclick2044]

Did you got answer?

[@hectorbarrera9496]

@@shoppingoneclick2044 nop

[@guloguloguy]

THANK YOU, FOR THIS WONDERFUL, CONCISE, AND WELL EXPLAINED LOOK AT THESE DEVICES!

[@miguelduran1549]

excellent video. can i connect 2 or 3 TRIAC in parallel to drive more powerfull loads ??? i need a optotriac to each TRIAC ??? thanks

[@LewisLoflin]

I wouldn't. Try paralleling 2-3 separate circuits. Yes you need an optocoupler for each circuit.

[@hellomilan03]

How you are sizing the resistors and capacitors in the optocoupler with a triac circuit with the snubber?

[@LewisLoflin]

Spec. sheets and working circuits. Optocouplers I allow 5-10mA. Snubbers spec. sheets, schematics.

[@moustafaelebiary735]

please circuit diagram using triacs for on and off led lamps with power supply 220

[@LewisLoflin]

You don't use triacs with DC or LEDs.

[@nurulbasyiroh1385]

sorry sir, why we can't use TRIAC for DC ? do you suggest Relay than Triac when we use DC?

[@LewisLoflin]

With DC once the triac is turned in with DC it will not turn off unless the DC is disconnected.

[@nurulbasyiroh1385]

+Lewis Loflin ooh I see. thank you very much sir

[@MitsuZer0G]

1:33 What power rating do the resistors R2, R3 and R1 need? 1/4 W? 1/2 W? 1 W?

[@LewisLoflin]

1/2 watt is what I used.

[@georgesdibeh7826]

Thank you Please how can i test a moc 3051 or 3052 in circuit and out of circuit With a digital multimeter

[@LewisLoflin]

You can only test the input LED maybe if the DVM can check LEDs. You can only check if the photo triac is shorted. It should read open.

[@ddvelzen]

Thanks, interesting video... I found some SSR which can control the phase based on input voltage (0/1-10V | 0 - 5V) or current 4-20mA ... How does these work and can these be used as dimmer for regular lightbulbs AND dimmable LED drivers... In the specs I could connect resistive and capacitive loads and simple cut the phase. These SSRS could be very interesting for my home automation and simply hook them to an Arduino pwm and simple RC. Or do you have better ways to create a steady but varying voltage using Arduino? Regards Dennis

[@Dharmendrasavaliya012]

Hello sir, How can we protect TRIAC From high current OR Overload ?

[@LewisLoflin]

Use a triac with specs above what is needed. If you need 3 amps use a 10 amp. A dead short circuit will wipe out anything. If this was DC which you can't use with a triac use a current limiter. How about a circuit breaker?

[@Dharmendrasavaliya012]

sir, i need less then 2A for lamp dimming & i have used BT137 8A triac for it. But i had found on blog that triac blow off before MCB .

[@shoppingoneclick2044]

I too Heard, people talk about failure of traic.

[@plinioabreu2185]

Hello, IF I want to use 120 volts, what is the values of resistor I must change, excuse me my english , thanks.

[@LewisLoflin]

Where are you in the video? In general the resistors are not critical.

[@plinioabreu2185]

@@LewisLoflin Thanks for answer, I am in the 5:52 time of video.

[@nayanjagirdar8408]

👌👍

[@meenakshimaurya7949]

what is power(watt) of 470R,0.05uf , 39R and 0.01uf component if load is 5KVA

[@LewisLoflin]

About 1 watt on the resistor and 5KV on the cap. This is a spike suppression circuit and isn't critical.

[@meenakshimaurya7949]

@@LewisLoflin 1W is enough for 39R .

[@LewisLoflin]

@@meenakshimaurya7949 In series with a cap there isn't much power in the circuits. It's a spike suppressor to prevent false triac gate firing.

[@meenakshimaurya7949]

@@LewisLoflin thanks

[@dvdm1dvdm1]

👍👍👍

[@parashdas8674]

why we are using a capacitor of 100n

[@LewisLoflin]

Spec sheet.

[@filips7158]

I really dislike schematic representation where input is on the right and the circuit on the left, with no clear separation between input hot/live and the output live wire. Makes schematics hard to read and it is even worse for understanding what the hell it does.

[@sidneipereira9971]

Top

[@thinhpham10886]

thanhs

[@thehighriseconstructionob9679]

What is triac ?

[@LewisLoflin]

A triac can be thought of as a solid state AC switch. Apply a small current to the gate it turns on.

[@thehighriseconstructionob9679]

@@LewisLoflin so triac is Base in transister ?

[@thehighriseconstructionob9679]

@@LewisLoflin thank you repray sir. triac is base in transister ?

[@LewisLoflin]

@@thehighriseconstructionob9679 No it is not a transistor. Its terminal are gate, MT1, and MT2. The gate must be triggered from MT1.

[@mspiero62]

Stari pappendi Fai buddia

[@peki1701]

How come the current doesn't run through the RC snubber circuit while the triac is closed?

[@LewisLoflin]

The snubber due to the small component values suppress/conducts the higher frequency, fast rise time noise spicks. 60Hz is ignored.

[@peki1701]

@@LewisLoflinThank you!

[@parthpatel1605]

SSR's are still a stupid stuff in compare to electromechanical realys.🥱

[@shoppingoneclick2044]

I didn't understand your question? You mean relays are better then , traic + optocoupler?