Electronics Lab Philippines

Emergency lighting - suggestion for improvement

Offline isabella

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Emergency lighting - suggestion for improvement
« on: October 31, 2020, 05:48:24 PM »
Tanong lang po ako ng pwede pa pong iimprove sa proposed project po namen: Emergency lighting with dimming control circuit using Thyristors. Maraming salamat po

Online Super zHero

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Re: Emergency lighting - suggestion for improvement
« Reply #1 on: October 31, 2020, 08:35:38 PM »
Yes,,,, use PWM instead of thyristors.  Assuming that you meant to use the thyristors to control the dimming.  Since this is Emergency Lighting, it would be understood that the lighting will be running on batteries, which is DC. Thyristors on DC once turned ON do not turn OFF unless you switch OFF the DC.  Hence, can't be dimmed.

Now, and since we are powering off of batteries, the best light source would be LEDs.  And the most efficient means to dim LEDs is by PWM (Pulse Width Modulation).  Can be simply done with a 555 circuit.

Offline isabella

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Re: Emergency lighting - suggestion for improvement
« Reply #2 on: November 01, 2020, 11:41:50 PM »
eto po yung circuit po namen, tanong ko lang po ulit ano po yung mga dapat na values, hindi po kasi gumagana yung scr kapag po namatay po yung power or naopen po sa main source

https://app.photobucket.com/u/IsabeIIa/p/3a47fccd-67ee-4f72-9bd3-bf9c5bbca164

Offline zirlou21

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Re: Emergency lighting - suggestion for improvement
« Reply #3 on: November 02, 2020, 12:10:35 AM »
...
  tanong lang para saan ang dimming emergency lighting nga ito.
...NO OFFENSE pls..usapang teknikal lang,walang personalan.....

Online Super zHero

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Re: Emergency lighting - suggestion for improvement
« Reply #4 on: November 02, 2020, 05:02:30 AM »
Ano ang gusto mong mangyari sa circuit?  Give a description of how you want it to work.

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Re: Emergency lighting - suggestion for improvement
« Reply #5 on: November 02, 2020, 05:50:18 PM »
The circuit works,,,, but I don't know what the purpose of the SCR is.

Offline isabella

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Re: Emergency lighting - suggestion for improvement
« Reply #6 on: November 03, 2020, 10:50:26 AM »
Emergency light po sana na kapag po nawalan ng kuryente, mag-on po sya, then if nawalan po ng kuryente sa umaga di po sya mag-oon dahil po sa LDR. Paano po ba sya di mag-on ka plug po sa AC, yung kagaya po sa mga commercial na emergency lights. Sa circuit po kasi na nagawa auto-on po sya kaagad.

Online Super zHero

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Re: Emergency lighting - suggestion for improvement
« Reply #7 on: November 03, 2020, 01:24:54 PM »
Tanong lang po ako ng pwede pa pong iimprove sa proposed project po namen: Emergency lighting with dimming control circuit using Thyristors. Maraming salamat po


Eh, saan dito ang dimming at kailangan ba ang SCR?

Offline zirlou21

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Re: Emergency lighting - suggestion for improvement
« Reply #8 on: November 03, 2020, 04:25:42 PM »
😀😀😀
...sa palagay ko ang understanding nila sa SCR ang siyang magsupply ng volage pag brownout from batt.,at ang LDR naman sa pagkaintindi nila ang magsense ng 'light and dark' surrounding,  sa hapon o pagabi na at dumilim saka pa lang iilaw at sa umaga na maliwanag na o maliwanag pa hindi iilaw pag nagbrownout.
...NO OFFENSE pls..usapang teknikal lang,walang personalan.....

Offline zirlou21

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Re: Emergency lighting - suggestion for improvement
« Reply #9 on: November 03, 2020, 04:40:36 PM »
😀😀😀
... kailangan dito total revision sa ckt design nila.,ang SCR ay dapat sa trickle charging lang ng battery, ang LDR ay dark sensor lang gaya ng expectation nila na sa hapon o afternoon lang dumidilim at doon pa lang mag-on ang ilaw sa brownout situation., yun nga lang may time din medyo o madilim sa umaga dahil minsan sa weather o what ever situation na matabingan ang sensor  kahit maliwanag pa sa umaga pwede mag-on ang ilaw. in any case yan suggestion ko lang.
...NO OFFENSE pls..usapang teknikal lang,walang personalan.....

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Re: Emergency lighting - suggestion for improvement
« Reply #10 on: November 03, 2020, 08:09:50 PM »
I don't think the SCR is needed or is correctly being used,,,, unless they are required to use it in this circuit.  If so, I would put it somewhere else- like in the Base of Q1 (just thinking aloud,,, don't know if that's gonna work....).

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Re: Emergency lighting - suggestion for improvement
« Reply #11 on: November 03, 2020, 11:48:11 PM »
FYI- I guess this is the grand-daddy of this circuit:



I got this from Encyclopedia of Electronics Circuits Vol. 1, compiled by Rudolf F. Graf. 1985
This appeared in a long ago topic on this forum.  I believe the question was if this would work.

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Re: Emergency lighting - suggestion for improvement
« Reply #12 on: November 04, 2020, 12:01:43 AM »
Here's the link of the July 2013 post but some of the photos are gone :

http://www.elab.ph/index.php?topic=40923.msg765284#msg765284


Offline isabella

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Re: Emergency lighting - suggestion for improvement
« Reply #13 on: November 04, 2020, 01:31:27 AM »
😀😀😀
...sa palagay ko ang understanding nila sa SCR ang siyang magsupply ng volage pag brownout from batt.,at ang LDR naman sa pagkaintindi nila ang magsense ng 'light and dark' surrounding,  sa hapon o pagabi na at dumilim saka pa lang iilaw at sa umaga na maliwanag na o maliwanag pa hindi iilaw pag nagbrownout.
yes po ganito nga po.

Offline isabella

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Re: Emergency lighting - suggestion for improvement
« Reply #14 on: November 04, 2020, 01:32:49 AM »
😀😀😀
... kailangan dito total revision sa ckt design nila.,ang SCR ay dapat sa trickle charging lang ng battery, ang LDR ay dark sensor lang gaya ng expectation nila na sa hapon o afternoon lang dumidilim at doon pa lang mag-on ang ilaw sa brownout situation., yun nga lang may time din medyo o madilim sa umaga dahil minsan sa weather o what ever situation na matabingan ang sensor  kahit maliwanag pa sa umaga pwede mag-on ang ilaw. in any case yan suggestion ko lang.
Thank you po sa suggestion. I rerework po namen yung circuit

Offline isabella

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Re: Emergency lighting - suggestion for improvement
« Reply #15 on: November 04, 2020, 01:34:09 AM »
I don't think the SCR is needed or is correctly being used,,,, unless they are required to use it in this circuit.  If so, I would put it somewhere else- like in the Base of Q1 (just thinking aloud,,, don't know if that's gonna work....).
Yes, required po ang thyristors po sa circuits. Noted po, try den po namen yung suggestion nyo. Thank you po

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Re: Emergency lighting - suggestion for improvement
« Reply #16 on: November 04, 2020, 11:57:50 PM »
I'd been working on this most of tonight and I finally got it simplified.

I'm using an MCR102, TO-92, 30V, 0.8A SCR.  I've had it for decades.  I think it's now obsolete.  Anyway, I got it to work with an LED.  I was first using a filament bulb but that gave me problems, maybe due to the higher current.


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Re: Emergency lighting - suggestion for improvement
« Reply #17 on: November 07, 2020, 12:14:23 AM »
This is my simplified circuit that works:



Component values will depend on your Triac and LDR.  These values work with mine.  You may substitute a pot for the 100K on the Base to Collector of the NPN for dark detect adjustment.

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Re: Emergency lighting - suggestion for improvement
« Reply #18 on: November 07, 2020, 12:21:35 AM »
You may also add a switch in between the battery and transistor.

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Re: Emergency lighting - suggestion for improvement
« Reply #19 on: November 07, 2020, 03:51:35 PM »
I thought I'd just throw this in.  This is the basic circuit for an old Akari Flashlight/Lantern that doubles as an Emergency Light when plugged to the wall being charged.  When switched to the Lantern mode (switch not shown) and the power goes out, the Lantern will come ON.  Otherwise when there is AC, the LEDs are OFF.



A Dark Detect circuit can be added to this.  I like this circuit because it doesn't use an expensive (and heavy) transformer.