need help with triac

[aruna1]

hi,this nt relevent with robotics,bt i could use a littel help. i'm working on a timer circuit to control a water pump.I used a BT139 as pump control switch.my problem is triac heats to very high tempreture.i guess its because i use it with its ful capacity.i dont have enough space to connect a heat sink as the circuit is tightly fitted into the box.i was wandering if i connect 2 or more BT139 triacs parallely can i reduce the heat?(is it possible to connect triacs parallely and oparate them with single MOC3023?) I checked for 40amp triac(BTA40) and its really really expensive.

[Soeren]

Hi,

If they're from the same production batch you may get away with it, as it's all about them each conducting an equal amount of current (if not, one will see all the hard work while the other(s) will idle).
If the MOC can handle the current, they can be run from the same one - just put a resistor of say 10..100 Ohm in-line with each gate.

It's something that you'll have to try to be absolutely sure, but take care with your pinkies!

(If you have room for a couple more BT139, you should have room for a small heat sink and a small piece of flanged aluminum may be all you need).
Are you sure you drive the TRIAC hard enough to open hard?

The MOC3023 will turn the TRIAC on anywhere in a period. If you use eg. either MOC3040 or MOC3060, you get zero cross switching, which will help if there's much on/off (and will reduce EMI from the TRIAC considerably).

[Abdulla M.A.]

Put in your mind dear, if you plan to use more than one Triac you have to use one of the electrical
isolations technique between the first and the second triggering circuit, i.e. you can't connect
both them directly to the same triggering circuit.
addition to that if you need to provide 40A (R.M.S.) you have to use 3 from BT139.

Abdulla

[Soeren]

Hi,

if you plan to use more than one Triac you have to use one of the electrical
isolations technique between the first and the second triggering circuit, i.e. you can't connect
both them directly to the same triggering circuit.

No need for isolation, just a resistor to each gate will do!

[Abdulla M.A.]

Hello,
I think the isolation required, do not forget that the Triac contain to SCR with Inverse-Parallel connection, and
when you plan to firing many SCR from the same firing cct. you need to use electrical isolation, which you can provide
it by using Pulse Transformer.

Abdulla

[Soeren]

Hi,

I think the isolation required,

It isn't, but feel free to think whatever you like

do not forget that the Triac contain to SCR with Inverse-Parallel connection,

What's your point of stating basic knowledge?
And why do you think that would require isolation?

when you plan to firing many SCR from the same firing cct. you need to use electrical isolation,

Well, whether you use one or many, you need to use electrical isolation to avoid the shock hazard of course.

which you can provide it by using Pulse Transformer.

No you can't, you can provide galvanic isolation, which is quite another thing!
Electric isolation it what you do with a non conducting material 

Perhaps you are forgetting that A1 and A2 (sometimes called Mt1 and Mt2) are parallel connected, or perhaps you just need to read a bit more on thyristors in general.
When a thyristor isn't trig'd, it will be off and when it's trig'd, it will keep conducting until the current through it falls under the threshold value.

A gate resistor is what it takes - like this:

[Abdulla M.A.]

Funny, anyway let me explain that to u, and before I do that,but in your mind, I have good info. about the practically using of the SCR and Triac, because I teach both them in the P.E. Lab, and I studied it for more then a year when I was student, after all I do not like to comments on your statements, I will just explain some things.
1-Pulse transformers are used to couple a triggering circuit to the gate and cathode of an SCR to provide electrical isolation between the triggering and power circuits(fig.1).
2-When multiple SCRs are used to control power, their cathodes are often not electrically common, making it difficult to connect a single triggering circuit to all SCRs equally. An example of this is the controlled bridge rectifier shown in (Fig.2).
3- In any bridge rectifier circuit the rectifying SCRs must conduct in opposite pairs. SCR1 and SCR3 must be fired simultaneously, and SCR2 and SCR4 must be fired together as a pair. As you will notice, though, these pairs of SCRs do not share the same cathode connections, meaning that it would not work to simply parallel their respective gate connections and connect a single voltage source to trigger both(fig.3).
4-Although the triggering voltage source shown will trigger SCR4, it will not trigger SCR2 properly because the two thyristors do not share a common cathode connection to reference that triggering voltage. Pulse transformers connecting the two thyristor gates to a common triggering voltage source will work(fig.4).

Abdulla

[Soeren]

Hi,

Funny, anyway let me explain that to u, and before I do that,but in your mind, I have good info. about the practically using of the SCR and Triac, because I teach both them in the P.E. Lab, and I studied it for more then a year when I was student, after all I do not like to comments on your statements, I will just explain some things.

I don't see anything funny about you being entrusted to teach people when you push this bad info 
Your arguments go haywire and then you try shuffling the deck by throwing in a rectifier bridge that has nothing to do with the parallelled TRIACs we are talking about *tsk tsk* parallel means well... Parallel - not "with other components in between".
Please review the examples I posted and do try it out in real life to see for yourself.

All that nonsense about teaching or studying the subject for a year doesn't make you right. If anything, I'd keep quiet about studying a simple subject for a year and still getting it wrong.

Btw. your last drawing, the one with the transformers is not complete.
I'd say you have pretty bad info on the subject, based on your adherence to wrong postulates, but don't take my word, test it yourself. Or take a look at this .

Please don't keep telling me that it won't work, it's tried and tested and I have used parallel TRIACs in several jobs over the years, so I know it works - now you try it, then you'll get some real life knowledge to pass on.

Btw2. it's either TriAC or TRIAC, not Triac - it's an acronym for TRIode for AC.

Btw3. You're not the only one allowed to teach,. Would you allow your students to go work on design of eg. aeronautics or life support systems when they graduate?

Sorry, I really don't mind peoples ignorance in general, but when they spread that ignorancee masked as knowledge, thereby crippling other peoples ability to learn, especially if you actually are a teacher (and then I really have to wonder about the avatar you had when you started out on this board), which I'm not totally convinced about, then I do have to respond in "plain language".

[aruna1]

Hi guys,
I wonder why forum mailing system didnt notify me through emails about replies  I have set instant notification at the time I'm making the original post.
anyway water pump was 4.1A rating pump connected to 15A line.(took lot of time to find the pump box.) so i was able to use a small relay,(small enough to fit there).as I couldnt find the pump details,initially i assumed it draws all 15A when operating and try to find a relay that can handle 15A.but now as it becomes 4.1A,I used a small 7A relay.It seems working,but there is a false triggering problem,so i add a few caps and diodes to stop effect of interfierences to the NE555 s trigger pin.I will check the modified circuit in morning and let you know the result

[aruna1]

Hi i was able to successfully complete it.here are some photos

[Abdulla M.A.]

Hmmm, do you know something, why do you think you have more knowledge than other people???
the design of the triggering circuit with pulse transformer is the best, you have to accept that.
addition to that, who you are in order to talk about my informations, what's you background?? sorry did you finished in
MIT or Harvard!!!!
otherwise, let us say you have good info in Triac, that's not mean you are the king of electronics!!!
at last I do not like to discuss people do not know about the correct scientific discussions,
and the circuits which I teach it is designed by professor, who have more than 100 research in IEEE and other big
scientific magazines.

Abdulla

[Abdulla M.A.]

BTW, this circuit not accurate, how you can control in power in accuracy form???
how you can give the correct firing angle??
you still change in variable resistor to get what you want!!!!!! bad cct.

Abdulla

[Soeren]

Hi,

Hi i was able to successfully complete it.here are some photos

Great 

But... Why 3 trimmers?

[aruna1]

Hi,

Hi i was able to successfully complete it.here are some photos

Great 

But... Why 3 trimmers?

three trimmers for set 3 time selections 5min,10min and 15min.

by the way i have a question.is it ok to operate the circuit 24x7 ? i mean i continuously supply power to transformer and it will keep NE555 in standby mode so when i press the button it will switch on the relay and after time up it will switch off and go to standby.

is there any danger in doing this or will this reduce life time of the unit?
thanks

[Soeren]

Hmmm, do you know something, why do you think you have more knowledge than other people???

I don't think I have more knowledge than [all] other people, but I do know I have loads more knowledge than you, not only from here, but you have opened your mouth on Dutchforce as well for some ~3 years now.

the design of the triggering circuit with pulse transformer is the best, you have to accept that.

No I don't, try it and see for yourself. (Why do you think you know more than other people?  )

addition to that, who you are in order to talk about my informations, what's you background?? sorry did you finished in
MIT or Harvard!!!!

First, my apologies to the remark on your earlier avatar by the way, it was not here but on Dutchforce that you started out with the fascistic skull and crossed machineguns (which really not added to your credibility).

I am a seasoned engineer who, as mentioned, have read you on Dutchforce as well and this alone gives me plenty of reason to be sceptic to what you say in general and besides I am perfectly able to "talk about your informations" alone on the grounds that you claim, that this circuit (that I have build more times than you have obviously even seen a TRIAC) don't work   

I don't see the relevance of where I studied (it was in DK) in that, as you get the main part of your knowledge after graduating.
Statistically speaking, around half of the persons graduating from any class is below average, even in Baghdad

otherwise, let us say you have good info in Triac, that's not mean you are the king of electronics!!!

You are the only one to ever call me that, so that's on your account. 
At most I have called my self "Sir N", but that's just to help people pronounce my name.

at last I do not like to discuss people do not know about the correct scientific discussions,

Well, I never conducts scientific discussions on the open web, neither does anybody else.

you started this discussion by postulating that a (well proven) coupling wouldn't work and try to back that up with circuits that has nothing to do with what we're discussing, so I don't really see the science in that.

Scientific debate would have meant that you tested the circuit as I suggested and it would have meant that you needed an open mind towards the fact that perhaps you have been programmed with faulty knowledge!

I cannot accept that you just claim that it doesn't work, as I have done it so many times.

Despite the discussion being started by your wrong postulate, you apparently just want me to say you are correct to call it a scientific discussion? Sorry, can't help you there.

and the circuits which I teach it is designed by professor, who have more than 100 research in IEEE and other big
scientific magazines.

If I had a dime for each flawed design by a professor...

Professors and teachers in general who's have their daily life in teaching faculties alone, are very often badly off the mark, lacking the grit of industrial designers, but that's not new... A lot of people consider "The Art of Electronics" as a "bible" in electronics, but it is flawed in several places and Wince Hill (one of the authors), while absolutely not stupid!, have been typical for this category of faculty teachers in a couple of debates I've had with him, even if he does have his own company for industrial design.
People who can, do - and people who can't teach.

Before you go further in this rather unscientific discussion, would it be possible to urge you to try paralleling two TRIACs the way I drew it and see for yourself?
Or are you just completely unwilling to learn?

[Soeren]

BTW, this circuit not accurate, how you can control in power in accuracy form???
how you can give the correct firing angle??
you still change in variable resistor to get what you want!!!!!! bad cct.

I didn't design the circuit, I just posted the link to the site presenting the (10 year old) patent to show you that other people have done parallel connected TRIACs the same way, so you really should tell the patent holder that his patent is declared void in Baghdad. Somehow I think they'd enjoy an email from you.

Apart from that, I don't see the circuit as particular bad, a little outdated perhaps, but it works fine I'm sure, as it is a simple phase control dimmer, no big deal in that, so I don't see how it should earn remarks like "not accurate" etc from you, who probably haven't done any serious analog design at all.

Yes, you change a potentiometer to control the firing phase angle, that's how such dimmer circuits go, but again, you're trying to pull the discussion into a direction that has nothing to do with the fact that you can use TRIACs parallelled without any pulse transformers.

Perhaps your next outburst should contain remarks that gravity is bad and should be banned? 

If you want me to take you serious, test the two parallel coupled TRIACs and use two 100 Ohm resistors on their gates to see that they'll work as a single TRIAC of an almost double current capacity.
If you don't wanna try it yourself, keeping on with your postulates will just have negative impact on how you appear.

[Soeren]

Hi,

three trimmers for set 3 time selections 5min,10min and 15min.

Ahh, OK.

by the way i have a question.is it ok to operate the circuit 24x7 ? i mean i continuously supply power to transformer and it will keep NE555 in standby mode so when i press the button it will switch on the relay and after time up it will switch off and go to standby.

is there any danger in doing this or will this reduce life time of the unit?

A little hard to tell without knowing neither the circuit, nor the components selected, but if the transformer is build for it (might say something on the label on that) and the schematic is sensible with respect to handling the power in each, permanent power should give a longer life on most components. Electrolytic caps will die sooner when powered constantly, as they are kept warmer than else and so will dry out sooner, but the main issue is keeping the temperature down (and you can get 105°C electrolytes if needs be, regular ones are 85°C max and the high temperature caps will live longer, even at eg. 40°C).
All semiconductors are more stressed by turning them on (inrush current is the sinner) than staying on.

If you want a more specific review of your circuit, please post the schematic.

[aruna1]

Hi,

three trimmers for set 3 time selections 5min,10min and 15min.

Ahh, OK.

by the way i have a question.is it ok to operate the circuit 24x7 ? i mean i continuously supply power to transformer and it will keep NE555 in standby mode so when i press the button it will switch on the relay and after time up it will switch off and go to standby.

is there any danger in doing this or will this reduce life time of the unit?

A little hard to tell without knowing neither the circuit, nor the components selected, but if the transformer is build for it (might say something on the label on that) and the schematic is sensible with respect to handling the power in each, permanent power should give a longer life on most components. Electrolytic caps will die sooner when powered constantly, as they are kept warmer than else and so will dry out sooner, but the main issue is keeping the temperature down (and you can get 105°C electrolytes if needs be, regular ones are 85°C max and the high temperature caps will live longer, even at eg. 40°C).
All semiconductors are more stressed by turning them on (inrush current is the sinner) than staying on.

If you want a more specific review of your circuit, please post the schematic.

hi this is the basic circuit(only with one trimmer)

[Soeren]

Hi,

hi this is the basic circuit(only with one trimmer)

Your trigger circuit is a bit strange. I understand you had problems with noise and hence the low impedance and large capacitors (shouldn't be needed though), but why the diode?

The easiest way for noise to enter is via the high impedance on the threshold pin (high impedance = susceptibility to pick up noise) and a way too large capacitance for any kind of precision - timing will drift with temperature.
I would add a resistor T1_base to T1_emitter of 1k and a diode like 1N4148 over T1_collector (cathode) to T1_emitter (anode) to protect T1 from inductive kicks and change D3 to a 1N4148 as well (it is much faster than the 1N400x and hence better suited as a free wheeling diode).

I don't understand D1 either. D3 should be as close as physical possible to the terminals of the relay and not with an extra diode in the way.
A 100nF to 470nF from pin 8 to pin1 of the 555 would probably do more to counter noise than what else you have changed, especially in the nMOS version of the 555.

For running 24/7, the most important would be getting the diodes around the relay and T1 straightened out, so that T1 doesn't break down some day, as that would likely make the pump go on - a failing transistor typically fail shorted.


If this is gonna be a permanent solution, I'd recommend a small controller for any timing beyond a minute.
An 8 pin controller with internal oscillator could be used. 2 pins for power (with a cap over the supply terminals), 2 or 3 pins for selecting the time periods, a single output to control a relay (via a transistor) and a pin for the start button - or it can be made to just fire once when power is applied and then switch itself off completely, saving power.
A controller with internal oscillator will be precise within 1%, this is impossible to achieve with the 555 circuit

[aruna1]

well D1 and D3to stop reverse voltage fed n to trigger pin and make trigger value 0 instantly and making it trigger it.before adding these diodes i had a problem of auto triggering at the moment relay switches off making it to turn on relay again.after adding these diodes i was able to stop that from happening.
it was stated in following tutorial http://physics.learnhub.com/lesson/5112-555-timer read under topic "Relay coils and other inductive loads"

i didn't go for a micro because they are very sensitive and easily burns out.

[Abdulla M.A.]

I don't think I have more knowledge than [all] other people, but I do know I have loads more knowledge than you, not only from here, but you have opened your mouth on Dutchforce as well for some ~3 years now.

I know you was in Dutchforce, you run away for unknown reason, but I still there, I just joined this forum to share what
I have. I joined the Dutchfore 3 years ago, but does that mean I still have the same information from that time !!!!! of course no. I learnd alot alot alot especially in PIC microcontrollers, I started build very complicated embedded systems,
but you run away so, you still think that I have old info., dear, I changed from the time I entered the Dutchforce.

the design of the triggering circuit with pulse transformer is the best, you have to accept that.

No I don't, try it and see for yourself. (Why do you think you know more than other people?  )

Me!!!! I do not think so!!

[Abdulla M.A.]

First, my apologies to the remark on your earlier avatar by the way, it was not here but on Dutchforce that you started out with the fascistic skull and crossed machineguns (which really not added to your credibility).

I sew it more beautiful than your avator.

I am a seasoned engineer who, as mentioned, have read you on Dutchforce as well and this alone gives me plenty of reason to be sceptic to what you say in general and besides I am perfectly able to "talk about your informations" alone on the grounds that you claim, that this circuit (that I have build more times than you have obviously even seen a TRIAC) don't work   

I would to hear about about what I have from info. , let me hear please speak loud.

I don't see the relevance of where I studied (it was in DK) in that, as you get the main part of your knowledge after graduating.
Statistically speaking, around half of the persons graduating from any class is below average, even in Baghdad

Haaha, did you do a research on my name!!!!!

 Abdulla

[Abdulla M.A.]

You are the only one to ever call me that, so that's on your account. 
At most I have called my self "Sir N", but that's just to help people pronounce my name.

where is your name??? it's just a group of symbols!!

I cannot accept that you just claim that it doesn't work, as I have done it so many times.

Really??? because this is not full circuit.
Claim? I do not have a time to claim.

Despite the discussion being started by your wrong postulate, you apparently just want me to say you are correct to call it a scientific discussion? Sorry, can't help you there.

if you said or not, this will not increase or decrease my info. , ok!!

 Abdulla

[Abdulla M.A.]

Professors and teachers in general who's have their daily life in teaching faculties alone, are very often badly off the mark, lacking the grit of industrial designers, but that's not new... A lot of people consider "The Art of Electronics" as a "bible" in electronics, but it is flawed in several places and Wince Hill (one of the authors), while absolutely not stupid!, have been typical for this category of faculty teachers in a couple of debates I've had with him, even if he does have his own company for industrial design.
People who can, do - and people who can't teach.

Before you go further in this rather unscientific discussion, would it be possible to urge you to try paralleling two TRIACs the way I drew it and see for yourself?
Or are you just completely unwilling to learn?

I will try to check your circuit, and we will see what's the better, but you do not tell me how you will give the correct firing angle directly???

Abdulla

[Soeren]

Hi,

well D1 and D3to stop reverse voltage fed n to trigger pin and make trigger value 0 instantly and making it trigger it.before adding these diodes i had a problem of auto triggering at the moment relay switches off making it to turn on relay again.after adding these diodes i was able to stop that from happening.

OK, but it seems to be an odd way of accomplishing that. Take a look at how I would do it with a 555. It's larger than what you want, but I didn't go for small in particular, as I just meant it as a way to show you how to minimize noise - if you study both the schematic and the PCB, you'll see what would take numerous posts to describe in detail.

it was stated in following tutorial http://physics.learnhub.com/lesson/5112-555-timer read under topic "Relay coils and other inductive loads"

It describes the free wheeling diode over the relay clamps and a diode going from the output of the 555. A little different from when you use a transistor to drive it.
You can see what I mean about the diodes in the schematic.

i didn't go for a micro because they are very sensitive and easily burns out.

Well, I have seen far more 555s die than micros, but that's probably because they're everywhere. If treated right, components doesn't burn out, but until embedded in a PCB, controllers are much more sensitive than an nMOS 555 (but that goes for MOSFETs and anything CMOS as well).
However, you build, you choose

[aruna1]

Hi,

well D1 and D3to stop reverse voltage fed n to trigger pin and make trigger value 0 instantly and making it trigger it.before adding these diodes i had a problem of auto triggering at the moment relay switches off making it to turn on relay again.after adding these diodes i was able to stop that from happening.

OK, but it seems to be an odd way of accomplishing that. Take a look at how I would do it with a 555. It's larger than what you want, but I didn't go for small in particular, as I just meant it as a way to show you how to minimize noise - if you study both the schematic and the PCB, you'll see what would take numerous posts to describe in detail.

it was stated in following tutorial http://physics.learnhub.com/lesson/5112-555-timer read under topic "Relay coils and other inductive loads"

It describes the free wheeling diode over the relay clamps and a diode going from the output of the 555. A little different from when you use a transistor to drive it.
You can see what I mean about the diodes in the schematic.

i didn't go for a micro because they are very sensitive and easily burns out.

Well, I have seen far more 555s die than micros, but that's probably because they're everywhere. If treated right, components doesn't burn out, but until embedded in a PCB, controllers are much more sensitive than an nMOS 555 (but that goes for MOSFETs and anything CMOS as well).
However, you build, you choose

hi can you tell me what are the purposes of C1,C6 , R2 and R5?

[Soeren]

I know you was in Dutchforce, you run away for unknown reason, but I still there,

I'm still there too, as I have been for quite some years, but a truckload of people thinning the board to something silly made me take a pause from posting on Dutchforce.

but you run away so, you still think that I have old info., dear, I changed from the time I entered the Dutchforce.

No, I'm there from time to time, I just don't wanna waste my time joining in such silly postings that seems to be such a large part of it these days - Dutchforce used to be a very good place.


No point in taking this any further, if you are so afraid of getting your fixed beliefs disproved, but don't claim you have learned a lot, when you take such stand in a matter where you could actually learn.

End of discussion, at least on my behalf - I can see why Dutchforce posts with the sole content being either "Chop", "Beam" or "Catch" really is more important than silly learning, but should you ever get around to spending a bit of your precious time on testing parallel TRIACs, we may reenter discussion. Until such time... I won't be wasting more time on you.

[Soeren]

Hi,

what are the purposes of C1,C6 , R2 and R5?

C1 is for noise decoupling at the trigger pin.
C6 is for snubbing what little of the flyback gets by D3 (An 1N4148 will take much more of the flyback than an 1N400x).
R2 is protection of the capacitor draining transistor in the 555, that otherwise sees quite large currents from a 470µF cap.
R5 is to close Q1 fast and reliable, as the nMOS 555 doesn't do a very good job of that.
 

[aruna1]

Hi,

what are the purposes of C1,C6 , R2 and R5?

C1 is for noise decoupling at the trigger pin.
C6 is for snubbing what little of the flyback gets by D3 (An 1N4148 will take much more of the flyback than an 1N400x).
R2 is protection of the capacitor draining transistor in the 555, that otherwise sees quite large currents from a 470µF cap.
R5 is to close Q1 fast and reliable, as the nMOS 555 doesn't do a very good job of that.

oh i see
Can you tell me more about R2? i got the rest but still R2 is unclear

[Abdulla M.A.]

No point in taking this any further, if you are so afraid of getting your fixed beliefs disproved, but don't claim you have learned a lot, when you take such stand in a matter where you could actually learn.

I have workbench, I have new books, I have Internet. I think this is enough things to learn more .

End of discussion, at least on my behalf - I can see why Dutchforce posts with the sole content being either "Chop", "Beam" or "Catch" really is more important than silly learning, but should you ever get around to spending a bit of your precious time on testing parallel TRIACs, we may reenter discussion. Until such time... I won't be wasting more time on you.

I do not like to waste my time too, so see you soon.

Abdulla