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Variable AC voltage control using TRIAC ceiling fan regulator
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yamanoor sairam
Fri, 14 May 10 05:12:43 +0000
Dear All,

I am trying to implement 0-230V variable voltage control to my high voltage power supply. I am using a ceiling fan regulator to do the same. But I am not able to control the voltage. When I keep the regulator in off position, I am able to keep the power supply to the module switched off. However, when I turn on the knob, the voltage is maintained at 50W, even when I try to vary my knob from 0% to 100%.

I connected my power supply using the following link:

http://www.circuitstoday.com/wp-content/uploads/2008/02/lamp-dimmer.JPG

I connected the line of my power supply directly. I connected the neutral end to the regulator and the other end of the regulator to the neutral line. What could be the possible reason that I am not able to control the voltage?

Yours Sincerely,
Sairam



18 replies folowing
Oli Glaser
Fri, 14 May 10 05:36:44 +0000

----- Original Message -----
From: "yamanoor sairam"
To: "Microcontroller discussion list - Public."
Sent: Friday, May 14, 2010 6:12 AM
Subject: [EE] Variable AC voltage control using TRIAC ceiling fan regulator


> Dear All,
>
> I am trying to implement 0-230V variable voltage control to my high
> voltage power supply. I am using a ceiling fan regulator to do the same.
> But I am not able to control the voltage. When I keep the regulator in off
> position, I am able to keep the power supply to the module switched off.
> However, when I turn on the knob, the voltage is maintained at 50W, even
> when I try to vary my knob from 0% to 100%.
>
> I connected my power supply using the following link:
>
> http://www.circuitstoday.com/wp-content/uploads/2008/02/lamp-dimmer.JPG
>
> I connected the line of my power supply directly. I connected the neutral
> end to the regulator and the other end of the regulator to the neutral
> line. What could be the possible reason that I am not able to control the
> voltage?
>


I think the circuit you link to will only work with AC voltage, the diac
pulsing current to switch the triac on and off rapidly, so the voltage is
either on/off. If you are using a DC source, you will need a similar circuit
but with a power mosfet. There are plenty of examples on the web, here is
one (for low voltage) -
http://www.eleccircuit.com/linear-light-dimmer-by-power-mosfet/

What is your power supply going to used for? A bench top power supply?

dicsEE
Fri, 14 May 10 05:53:19 +0000
 
Oli Glaser
Fri, 14 May 10 05:53:19 +0000
I forgot to mention that the MOSFET circuit is not ideal for variable
voltage for a bench power supply. The circuit I linked to just controls
current through the lamp. It would have to be set up differently to vary
voltage and would be pretty inefficient. A better way would be to use some
kind of SMPS buck circuit I think, but I'm sure others can advise you better
in that area.

yamanoor sairam
Fri, 14 May 10 06:33:30 +0000
Hi.

Thanks for your mail. The power supply module that I am planning to control is one used for an ozone generator. It is a MOSFET based pulse width modulated power supply which drives a HT transformer. I want the 0-230V control externally since I bought the module ready from the market. When I vary the voltage, I would be able to vary the equivalent ozone output. I would have a preferred an auto transformer for that. I find it to be bulky and evaluating a low cost option and hence I chose a ceiling fan TRIAC voltage regulator.

Yours Sincerely,
Sairam


________________________________
From: Oli Glaser
To: Microcontroller discussion list - Public.
Sent: Fri, May 14, 2010 11:06:44 AM
Subject: Re: [EE] Variable AC voltage control using TRIAC ceiling fan regulator


----- Original Message -----
From: "yamanoor sairam"
To: "Microcontroller discussion list - Public."
Sent: Friday, May 14, 2010 6:12 AM
Subject: [EE] Variable AC voltage control using TRIAC ceiling fan regulator


> Dear All,
>
> I am trying to implement 0-230V variable voltage control to my high
> voltage power supply. I am using a ceiling fan regulator to do the same.
> But I am not able to control the voltage. When I keep the regulator in off
> position, I am able to keep the power supply to the module switched off.
> However, when I turn on the knob, the voltage is maintained at 50W, even
> when I try to vary my knob from 0% to 100%.
>
> I connected my power supply using the following link:
>
> http://www.circuitstoday.com/wp-content/uploads/2008/02/lamp-dimmer.JPG
>
> I connected the line of my power supply directly. I connected the neutral
> end to the regulator and the other end of the regulator to the neutral
> line. What could be the possible reason that I am not able to control the
> voltage?
>


I think the circuit you link to will only work with AC voltage, the diac
pulsing current to switch the triac on and off rapidly, so the voltage is
either on/off. If you are using a DC source, you will need a similar circuit
but with a power mosfet. There are plenty of examples on the web, here is
one (for low voltage) -
http://www.eleccircuit.com/linear-light-dimmer-by-power-mosfet/

What is your power supply going to used for? A bench top power supply?




yamanoor sairam
Fri, 14 May 10 06:35:49 +0000
If you are using a DC source, you will need a similar circuit
but with a power mosfet.


I am using an AC 220V source.

Sairam


________________________________
From: Oli Glaser
To: Microcontroller discussion list - Public.
Sent: Fri, May 14, 2010 11:06:44 AM
Subject: Re: [EE] Variable AC voltage control using TRIAC ceiling fan regulator


----- Original Message -----
From: "yamanoor sairam"
To: "Microcontroller discussion list - Public."
Sent: Friday, May 14, 2010 6:12 AM
Subject: [EE] Variable AC voltage control using TRIAC ceiling fan regulator


> Dear All,
>
> I am trying to implement 0-230V variable voltage control to my high
> voltage power supply. I am using a ceiling fan regulator to do the same.
> But I am not able to control the voltage. When I keep the regulator in off
> position, I am able to keep the power supply to the module switched off.
> However, when I turn on the knob, the voltage is maintained at 50W, even
> when I try to vary my knob from 0% to 100%.
>
> I connected my power supply using the following link:
>
> http://www.circuitstoday.com/wp-content/uploads/2008/02/lamp-dimmer.JPG
>
> I connected the line of my power supply directly. I connected the neutral
> end to the regulator and the other end of the regulator to the neutral
> line. What could be the possible reason that I am not able to control the
> voltage?
>


I think the circuit you link to will only work with AC voltage, the diac
pulsing current to switch the triac on and off rapidly, so the voltage is
either on/off. If you are using a DC source, you will need a similar circuit
but with a power mosfet. There are plenty of examples on the web, here is
one (for low voltage) -
http://www.eleccircuit.com/linear-light-dimmer-by-power-mosfet/

What is your power supply going to used for? A bench top power supply?




Russell McMahon
Fri, 14 May 10 06:47:24 +0000
> ... when I turn on the knob, the voltage is maintained at 50W, even when
> I try to vary my knob from 0% to 100%.


> http://www.circuitstoday.com/wp-content/uploads/2008/02/lamp-dimmer.JPG


> I connected the line of my power supply directly. I connected the neutral end to the regulator and the other end of the regulator to the neutral line. What could be the possible reason that I am not able to control the voltage?



Too many unknowns.

- You say "TO my high voltage power supply". Do you mean TO or AS - ie
is the load a power supply or a simple resistor etc.

- You say " ... at 50 W ..." which MAY be what you mean - but could
mean 50 Volt or 50% or ???
ie 50 Watt implies a load and some power supply characteristics.

SO

0 - AC mains used. Correct?
Circuit WILL NOT WORK on DC.

1 - Try this first and answer the question.
If you use a 100 Watt filament lamp as the load what happens?

2 - THEN - What is the "load" you wish to use (nature and value)?
If the load IS a power supply and not a resistor etc, describe it in
more detail.

Proceeding with an answer to 2 without first trialing and answering 1.
will (quite justifiably) wake up the troll under the bridge :-).

If answer to 0 is "DC" then move to new circuit :-).



Russell
yamanoor sairam
Fri, 14 May 10 07:16:03 +0000
Dear Russell,


Thanks for your reply.

>>0 - AC mains used. Correct?

I am connecting 230V AC to the terminal connectors.

>>- You say "TO my high voltage power supply". Do you mean TO or AS - ie
>>is the load a power supply or a simple resistor etc.


The load is a power supply module. Its power consumption is 50W.

>>1 - Try this first and answer the question.
>>If you use a 100 Watt filament lamp as the load what happens?


I tried the same connection to a 40W tungsten filament lamp. The result was same. I could observe the lamp flickering. However, there was not visible difference in the light getting dimmed. I am worried whether I have connected it wrong.

>>2 - THEN - What is the "load" you wish to use (nature and value)?
>>If the load IS a power supply and not a resistor etc, describe it in

more detail.

The load is a power supply module that is inductive in nature. You can connect this to corona discharge cells to produce ozone gas. Its power consumption is 50W approximately.

Yours Sincerely,
Sairam



Russell


Russell McMahon
Fri, 14 May 10 07:28:46 +0000
> The power supply module that I am planning to control is one used for an ozone generator. It is a MOSFET based pulse width modulated power supply which drives a HT transformer. I want the 0-230V control externally since I bought the module ready from the market. When I vary the voltage, I would be able to vary the equivalent ozone output. I would have a preferred an auto transformer for that. I find it to be bulky and evaluating a low cost option and hence I chose a ceiling fan TRIAC voltage regulator.


MUCH better information. Thanks.

1. Try a light bulb as I suggested.
This allows you to be sure that the TRIAC circuit is in fact working
as intended. Even such a simple circuit can have "interesting" faults.

2. The circuit works by charging C1 via load + R1a + R1b to a voltage
where the DIAC breaks down and triggers the TRIAC gate on. The time
constant is from about 1/1000 second when R1b=0 to about 0.01 second
when R1b = 100k *IF* the load resistance is small compared to R1a or
R1b

The off FET PWM circuit probably appears as a low current highish
resistance path until the FET fires.

*** STOP PRESS *** :-)

Just saw your reply re bulb.

Make the bulb work first (which was the reason I suggested it).
Then proceed to the power supply.

Is the TRIAC dead?
Are the connections correct?
Is the DIAC dead (less likely)?

The DIAC can be shorted out and the circuyit will still function, but
not as well.

TRIAC MAY be shorte circuit on or connected wrongly.

Are you using an actual BT136 or some other TRIAC. If other, what. Can
you refer us to a web datasheet? (Always useful).
This may apply:

http://www.nxp.com/documents/data_sheet/BT136S_SERIES_E.pdf

In ANY problem situation with too many unknowns, try to reduce
unknowns so you can deal with one unknown at a time. Here, a lamp load
is much less likely to fool you than a FET power supply.



Russell
Oli Glaser
Fri, 14 May 10 07:38:40 +0000
>I tried the same connection to a 40W tungsten filament lamp. The result was
>same. I could observe the lamp >flickering. However, there was not visible
>difference in the light getting dimmed. I am worried whether I have
> >connected it wrong.


It seems something might be wrong here, can you look at the waveform(s) with
an oscilloscope to see if the triac is working correctly?


Michael Watterson
Fri, 14 May 10 07:49:46 +0000
yamanoor sairam wrote:
>
> The load is a power supply module that is inductive in nature. You can connect this to corona discharge cells to produce ozone gas. Its power consumption is 50W approximately.
>
> Yours Sincerely,
> Sairam
>
>

If the ozone generator's initial PSU is a switch mode type, then it
rectifies incoming AC and simply takes more current as you turn down
Triac. At some point this may cause the Triac to fail when the Ozone PSU
reaches x3 current input

If it's a SMPSU based unit, then you can't externally vary its output.
Oli Glaser
Fri, 14 May 10 08:21:59 +0000

----- Original Message -----
From: "Michael Watterson"
To: "Microcontroller discussion list - Public."
Sent: Friday, May 14, 2010 8:49 AM
Subject: Re: [EE] Variable AC voltage control using TRIAC ceiling fan
regulator


> yamanoor sairam wrote:
>>
>> The load is a power supply module that is inductive in nature. You can
>> connect this to corona discharge cells to produce ozone gas. Its power
>> consumption is 50W approximately.
>>
>> Yours Sincerely,
>> Sairam
>>
>>
> If the ozone generator's initial PSU is a switch mode type, then it
> rectifies incoming AC and simply takes more current as you turn down
> Triac. At some point this may cause the Triac to fail when the Ozone PSU
> reaches x3 current input
>
> If it's a SMPSU based unit, then you can't externally vary its output.
> --


This is a good point, some information on the PS module would be useful, and
the thinking behind using a triac before it to have the end result of
controlling the ozone output. Also what voltage range the ozone unit uses
and how it is designed to work/vary output - a link to any info on the unit
would be good. If it is a varying DC voltage, then maybe just a variac with
a rectifier/filter section might do, or something along those lines.

yamanoor sairam
Fri, 14 May 10 09:25:02 +0000
>>If it's a SMPSU based unit, then you can't externally vary its output.

Thanks for your mail.

I checked the power supply module and found that they have used a BR68 bridge rectifier at its input. Is this the main reason behind the voltage not being controlled? I measured the voltage and observed that 230Vac is being converted to 330V DC to power the primary of the transformer.

However I am not able to drive the bulb yet. I shall check the same.

Sairam


________________________________
From: Michael Watterson
To: Microcontroller discussion list - Public.
Sent: Fri, May 14, 2010 1:19:46 PM
Subject: Re: [EE] Variable AC voltage control using TRIAC ceiling fan regulator

yamanoor sairam wrote:

>
> The load is a power supply module that is inductive in nature. You can connect this to corona discharge cells to produce ozone gas. Its power consumption is 50W approximately.
>
> Yours Sincerely,
> Sairam
>
>

If the ozone generator's initial PSU is a switch mode type, then it
rectifies incoming AC and simply takes more current as you turn down
Triac. At some point this may cause the Triac to fail when the Ozone PSU
reaches x3 current input

If it's a SMPSU based unit, then you can't externally vary its output.


Michael Watterson
Fri, 14 May 10 10:07:24 +0000
yamanoor sairam wrote:
>>> If it's a SMPSU based unit, then you can't externally vary its output.
>>>
>
> Thanks for your mail.
>
> I checked the power supply module and found that they have used a BR68 bridge rectifier at its input. Is this the main reason behind the voltage not being controlled? I measured the voltage and observed that 230Vac is being converted to 330V DC to power the primary of the transformer.
>
> However I am not able to drive the bulb yet. I shall check the same.
>
> Sairam
>
>

Ok, you can't control the Ozone power by external varying of supply.
That won't work. Trying it initially maybe destroyed the Triac to a
Short Circuit as the current spikes will increase dramatically on such a
PSU fed by triac as you dim.

(I've seen them fail short rather than open feeding Halogen lamps which
have higher "on" surge and often the 50W "par" reflector "twist in"
halogens fail with surge that takes out dimmer and flips trip on board).


Also some Dimmers for heaters or fans may be full cycle on-off type,
where the number of cycles in a fraction of a second is varied. They
have much less interference than phase per cycle type used for lamp
dimmers, and will run a bulb at full brightness but flicker it more as
you turn it down. The physical inertial of the fan makes it work with
such a controller, whereas a fan motor is inductive, so lamp bulb type "
% phase angle" controller would be "a bad idea (tm)".

Also diac + triac can't be turned off. It's the AC mains voltage AC
nature makes it turn off twice a cycle as current goes to zero. The diac
or other device can only turn a Triac on. Inherently they are only good
for AC. It's like a pair of Thyristors/SCRs back to back in parallel.
Those work on DC, but you can only turn them on. The fuse blowing
or the lack of current when a capacitor is discharged turns them of.

I can't imagine exactly what would happen feeding a AC-> rectified DC ->
SMPSU with such a "duty cycle" rather than "% phase angle" dimmer. If
the capacitors are big enough and "flickering" fast enough, it would
have no effect.

yamanoor sairam
Fri, 14 May 10 11:49:54 +0000
Dear All,

I would like to thank Michael, Oli and Russell for their contribution. I tried replacing the BT136 TRIAC. I was able to dim a filament lamp. I later connected the ozone generator power supply. It didn't work. I tried connecting the filament lamp once again. Now it didnt work for the filament lamp too. The TRIAC blew up!

Is there any other method other than the autotransformer method to vary the external supply voltage.

Can I remove the track where at the DC output end and connect a potentiometer in between? Am I prone to a potential shock hazard due to 330V DC?

Yours Sincerely,
Sairam



________________________________
From: Russell McMahon
To: Microcontroller discussion list - Public.
Sent: Fri, May 14, 2010 12:58:46 PM
Subject: Re: [EE] Variable AC voltage control using TRIAC ceiling fan regulator

> The power supply module that I am planning to control is one used for an ozone generator. It is a MOSFET based pulse width modulated power supply which drives a HT transformer. I want the 0-230V control externally since I bought the module ready from the market. When I vary the voltage, I would be able to vary the equivalent ozone output. I would have a preferred an auto transformer for that. I find it to be bulky and evaluating a low cost option and hence I chose a ceiling fan TRIAC voltage regulator.



MUCH better information. Thanks.

1. Try a light bulb as I suggested.
This allows you to be sure that the TRIAC circuit is in fact working
as intended. Even such a simple circuit can have "interesting" faults.

2. The circuit works by charging C1 via load + R1a + R1b to a voltage
where the DIAC breaks down and triggers the TRIAC gate on. The time
constant is from about 1/1000 second when R1b=0 to about 0.01 second
when R1b = 100k *IF* the load resistance is small compared to R1a or
R1b

The off FET PWM circuit probably appears as a low current highish
resistance path until the FET fires.

*** STOP PRESS *** :-)

Just saw your reply re bulb.

Make the bulb work first (which was the reason I suggested it).
Then proceed to the power supply.

Is the TRIAC dead?
Are the connections correct?
Is the DIAC dead (less likely)?

The DIAC can be shorted out and the circuyit will still function, but
not as well.

TRIAC MAY be shorte circuit on or connected wrongly.

Are you using an actual BT136 or some other TRIAC. If other, what. Can
you refer us to a web datasheet? (Always useful).
This may apply:

http://www.nxp.com/documents/data_sheet/BT136S_SERIES_E.pdf

In ANY problem situation with too many unknowns, try to reduce
unknowns so you can deal with one unknown at a time. Here, a lamp load
is much less likely to fool you than a FET power supply.



Russell



Michael Watterson
Fri, 14 May 10 12:06:15 +0000
yamanoor sairam wrote:
> Dear All,
>
> I would like to thank Michael, Oli and Russell for their contribution. I tried replacing the BT136 TRIAC. I was able to dim a filament lamp. I later connected the ozone generator power supply. It didn't work. I tried connecting the filament lamp once again. Now it didnt work for the filament lamp too. The TRIAC blew up!
>
> Is there any other method other than the autotransformer method to vary the external supply voltage.
>
> Can I remove the track where at the DC output end and connect a potentiometer in between? Am I prone to a potential shock hazard due to 330V DC?
>
> Yours Sincerely,
> Sairam
>
>

Probably the Ozone generator can't work with a variable supply.

Possibly the actual generator can only be on or off, likely needing a
minimum voltage to work.

Try it with a plug in timer. Either mechanical one (each on/off in 24hrs
is a 15 min segment that pushes in/out) and vary from 15min to 2hrs
per 2hrs in 8 15min steps

Or electronic timer of a suitable nature. i.e. to have 100th output,
have it on for 10 seconds in 1000 seconds.

I think "direct proportional" control via any power/voltage varying
method on AC mains or internally on the PSU is unlikely to work as
Ozone generator likely works only over a narrow voltage range. Too
little and you get none, too much and it's an Arc lamp.
Mark E. Skeels
Fri, 14 May 10 12:32:05 +0000
I like your answer, Russell.

:-)

Mark Skeels
Engineer
Competition Electronics, Inc.
TEL: 815-874-8001
FAX: 815-874-8181
www.competitionelectronics.com


Russell McMahon wrote:

>> ... when I turn on the knob, the voltage is maintained at 50W, even when
>> I try to vary my knob from 0% to 100%.
>>
>
>
>> http://www.circuitstoday.com/wp-content/uploads/2008/02/lamp-dimmer.JPG
>>
>
>
>> I connected the line of my power supply directly. I connected the neutral end to the regulator and the other end of the regulator to the neutral line. What could be the possible reason that I am not able to control the voltage?
>>
>
>
> Too many unknowns.
>
> - You say "TO my high voltage power supply". Do you mean TO or AS - ie
> is the load a power supply or a simple resistor etc.
>
> - You say " ... at 50 W ..." which MAY be what you mean - but could
> mean 50 Volt or 50% or ???
> ie 50 Watt implies a load and some power supply characteristics.
>
> SO
>
> 0 - AC mains used. Correct?
> Circuit WILL NOT WORK on DC.
>
> 1 - Try this first and answer the question.
> If you use a 100 Watt filament lamp as the load what happens?
>
> 2 - THEN - What is the "load" you wish to use (nature and value)?
> If the load IS a power supply and not a resistor etc, describe it in
> more detail.
>
> Proceeding with an answer to 2 without first trialing and answering 1.
> will (quite justifiably) wake up the troll under the bridge :-).
>
> If answer to 0 is "DC" then move to new circuit :-).
>
>
>
> Russell
>
Oli Glaser
Fri, 14 May 10 12:32:53 +0000

----- Original Message -----
From: "yamanoor sairam"
To: "Microcontroller discussion list - Public."
Sent: Friday, May 14, 2010 12:49 PM
Subject: Re: [EE] Variable AC voltage control using TRIAC ceiling fan
regulator


> Dear All,
>
> I would like to thank Michael, Oli and Russell for their contribution. I
> tried replacing the BT136 TRIAC. I was able to dim a filament lamp. I
> later connected the ozone generator power supply. It didn't work. I tried
> connecting the filament lamp once again. Now it didnt work for the
> filament lamp too. The TRIAC blew up!
>
> Is there any other method other than the autotransformer method to vary
> the external supply voltage.
>
> Can I remove the track where at the DC output end and connect a
> potentiometer in between? Am I prone to a potential shock hazard due to
> 330V DC?
>


Sounds like the triac is being asked to pass too much current, so it blows.
Anyway this is not the solution to your problem.
The potentiometer would not be a good idea with that voltage and current, it
would probably be very unsafe. Even if you could find a suitable mains rated
one, it would be too inefficient anyway. Don't try this.

In my view, the variable transformer would seem to me like the best choice
to supply the ozone unit directly (after rectification and filtering) but
without knowing more about it, I couldn't be sure that would have the
desired effect either.

Also, certainly from my point of view (as I don't know anything about ozone
generators) it would be good to know the voltage and power rating of the
ozone unit, to help judge the best solution. Also why you think reducing the
input voltage will produce less ozone (rather than just stopping it from
working). Are you going from the manufacturers specifications/instructions
or is it just an idea of yours?
What is the model of the ozone generator? Is it like this one:
http://www.ozoneapplications.com/products/ozonegenerators/SR-8_ozone_generator.htm
If it is, it may be the case that the ozone output cannot be adjusted at
all, without modifying the unit itself. This model appears to require a
pretty fixed input voltage (100-120V) and I think reducing it would probably
just stop it working.

Oli Glaser
Fri, 14 May 10 12:38:49 +0000
>Or electronic timer of a suitable nature. i.e. to have 100th output,
>have it on for 10 seconds in 1000 seconds.


Just saw this idea from Michael, and I think it is probably by far the
easiest/cheapest/safest solution, however the ozone unit works.

Russell McMahon
Fri, 14 May 10 13:06:22 +0000
>> Is there any other method other than the autotransformer method to vary
>> the external supply voltage.


The on/off method with periods in the order of seconds is probably the
best you'll get.

BUT - try:

1. IF you have a 100 Watt+_ Variac try using that.
Start with it set to rated voltage.
Turn down a little.
See what happens.
Ensure ozone generator is not "distressed"
Repeat gradual turn down.

Destruction of ozone generator possible.

2. If no variac.


Connect 4 !!! lightbulb sockets in parallel,
Put a 100 Watt bulb in each.
Connect the 4 sockets in series with the ozone generator.

Phase
I
I
I
---------
BBBB
---------
|
Generator.
|
Neutral

Power on.
Ensure generator is not 'distressed'
Measure voltage across bulbs and generator.
See what happens to ozone production.

If all works OK.

Turn off mains.
Remove 1 bulb.
Turn on.
Repeat as above.

If you get to 1 x 100 Watt bulb and ozone is still being made and
generator is happy, try successively lower wattage bulbs.

Success is unlikely.

3. Contact generator maker.
It WILL be possible to reduce ozone generation rate.
They may be able and willing to suggest how.

>> Can I remove the track where at the DC output end and connect a
>> potentiometer in between? Am I prone to a potential shock hazard due to
>> 330V DC?


It depends on how well insulated you are :-).
If you are not personally CAT IV mains rated you should take suitable
precautions.


Russell