Component questions

Thread Starter

DWiseguy

Joined Nov 7, 2020
17
I am at ground zero with this idea so please bear with my ignorance. I make desk lamps, I would like to incorporate low voltage LED bulbs with separate 120V incandescent using a three position rotary switch. The switch would be built into the base, or the wire if a wire installed switch exist. In my mind I see a wire like a USB that would carry the 120V and the Led wires. This would plug into a power supply that would handle both circuits, which then would plug into the wall. I do not need the low voltage LED but in my cursory search that is all I find in the bulbs that will work for my idea. I do not have room in the lamp base for any type of convertor that I have seen. Ground zero!
I hope I have been clear in my description.
Thanks for any assistance
Dave
 

rsjsouza

Joined Apr 21, 2014
331
The switch can be a three position (rotary, lever or slide) single pole where its common pin would be connected to the 120V live and the other two positions would be either powering the incandescent or the power supply for the LEDs. Make sure you get one that is properly rated for 120V and the current consumed by the highest power device: either the incandescent or the power supply.

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In my mind I see a wire like a USB that would carry the 120V and the Led wires. This would plug into a power supply that would handle both circuits, which then would plug into the wall.
The sentence "wire like a USB" makes very little sense. Regardless of what you do, USB wires are not properly rated for 120V circuits.
 
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Thread Starter

DWiseguy

Joined Nov 7, 2020
17
Thanks for the response. I have used three position switches in the past, so I am familiar with them, thanks. The LED lamps I would like to use are about the size of a pea. What I see on Amazon are 12V with leads and a resistor built in would, I think, work for my idea. I do not have room in the lamp base for a convertor, so what I see, in my limited knowledge is a power cord with wires for the incandescent bulb and wires for the LED. All the individual wires would be inside a single shroud with a plug on one end to plug into a compatible power supply that would 'separate' the AC and DC. The power supply would then plug into the AC outlet. Common sense tells me I can't be the first to want this. Or else I lay awake at night trying to complicate my life. Of course I can't use a USB cord! I should have stated that all better.
 

Ian0

Joined Aug 7, 2020
2,668
Why use the filament lamp at all? Get an LED with the appropriate colour temperature and a good colour-rendering index.
 

rsjsouza

Joined Apr 21, 2014
331
Thanks for the response. I have used three position switches in the past, so I am familiar with them, thanks. The LED lamps I would like to use are about the size of a pea. What I see on Amazon are 12V with leads and a resistor built in would, I think, work for my idea.
What is the exact purpose of the LEDs? Is it the main source of lighting or simply indication or decorative around the desk lam? Also, how many do you think you need? That would help specifying the 120V -> 12V converter and consequently giving you an idea on the size you need for it.

I do not have room in the lamp base for a convertor, so what I see, in my limited knowledge is a power cord with wires for the incandescent bulb and wires for the LED. All the individual wires would be inside a single shroud with a plug on one end to plug into a compatible power supply that would 'separate' the AC and DC. The power supply would then plug into the AC outlet.
Perhaps nomenclature needs to be reset. Your differentiation between a convertor and a compatible power supply are a bit confusing. What you definitely need is a way to convert the 120V into 12V to power the LEDs, which we call a "power supply".

I don't know how you imagine the unit physically but, if you are calling "power supply" a wall adapter, then you would need a four way wire from the "power supply" to the desk lamp: one pair of wires carries the 12V to the LEDs and the other pair carries the 120V to the lightbulb. The regular wall adapters sold in the marketplace do not usually do that - you would need a special order.

Also, given the voltages are very different, you can't use a single pole three position switch: the use of a dual pole three position switch would be mandatory, but that will complicate the assembly of the product (a crossed wire will be fatal to the LED and maybe the user, depending on conditions) and perhaps some certification red flags (depending on the market you intend to sell this).

Common sense tells me I can't be the first to want this. Or else I lay awake at night trying to complicate my life.
I suspect you are complicating your life, but what else is new when we are trying to do something out of our comfort zone? :)

For the looks of a visible filament glowing in a clear bulb.
Depending on where one lives, there are available decorative LED lightbulbs with "vintage-style" filaments and clear glass. Not exactly the real deal, but they look alright.

https://www.nostalgicbulbs.com/collections/led-bulbs
 

MisterBill2

Joined Jan 23, 2018
9,028
OK, I have read thru this thread so far. The solution is to have the entire lamp asembly powered by 12 volts. There are a broad range of 12 volt filament type bulbs available, and with 12 volt power there will not be a shock hazard. And running LEDs on 12volts will simply require a resistor to limit the current. The value of he resistor will depend on the kind and quantity of the LEDs.
 
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Thread Starter

DWiseguy

Joined Nov 7, 2020
17
To help simplify, here is a sample of my lamps. Under the insulator is an incandescent flicker bulb, candelabra base, 120V AC. The bulb does not touch the insulator. The plan is to use a larger base and have the LED's on a small 'post' not sure what as of yet, numerous ideas floating in the gray matter. Not sure how many, four at the most. The LED would not show, well maybe, there would be something above it, a marble? Now the gray matter is starting to boil. So as I understand this so far I would use four wire with a double pole three position switch. Or two switches, but a single switch would be cooler. Now I see a 'special' plug to plug into a 'special' convertor / power supply combination which would then plug into the wall outlet. It seems so simple IF the simple components exist
 

MisterBill2

Joined Jan 23, 2018
9,028
Now I see. These are sculptures, pieces of art! And it is important to keep it safe, which is the second reason for using 12 volt light bulbs as well as low voltage LEDs. Then the power converter at the wall plugwill only need a two conductor cable to the switch, and all of the wires will be12 volt power only, much safer than mains voltage.
 

Ian0

Joined Aug 7, 2020
2,668
Now I see. These are sculptures, pieces of art! And it is important to keep it safe, which is the second reason for using 12 volt light bulbs as well as low voltage LEDs. Then the power converter at the wall plugwill only need a two conductor cable to the switch, and all of the wires will be12 volt power only, much safer than mains voltage.
And your art won't be compromised by having to adhere to creepage and clearance distances.
 

Thread Starter

DWiseguy

Joined Nov 7, 2020
17
Thanks to all for the replies. I am well aware that I could run the whole lamp on 12V LED, but where do I get a 12V flicker bulb?
To anniel747, no the electrodes do not spark, but you got me thinking. There must be a 'special' convertor with 'special' cables that would create a static electrical spark. A spark across the electrodes with a flicker under the insulator, oh yeah!
 

MisterBill2

Joined Jan 23, 2018
9,028
We have had LED fake candles that flicker uch like the real ones. . So such functions do exist. Scaling up yo control a 12 volt incandescent lightshould not be excessive work.
 

Thread Starter

DWiseguy

Joined Nov 7, 2020
17
On Amazon I typed in '12V LED flicker bulbs'. I saw many battery powered bulbs but only one candle stick lamp pair. Batteries seem like a problem as I am trying sell these things. The less owner maintenance the better.
Does anyone know of a source for 12V LED flicker bulbs that act like filament bulbs
 

Ian0

Joined Aug 7, 2020
2,668
Have you considered designing your own circuit boards with LEDs on ? You can then make them any peculiar shape to fit whatever design you are working on, and any combination of colours.
It doesn't take much circuitry to implement a "flicker" function,
 

Thread Starter

DWiseguy

Joined Nov 7, 2020
17
Eureka ! I have discovered my misunderstanding of this project. I just need flicker and constant LED's, wired correctly so I can use a three position switch with the proper convertor- power supply.
What I found is from Edgelec. Part # ED-YT05_FLK-W_100pcs. One customer review thought the resistors, with the constant bulbs got to hot. I assume the flickers would heat up the resistors the same, however that was only one reviewer with that observation. So, any comments on the heating issue? Can I use a three position switch rated for 120V AC, or is there something more suited for low voltage?
Thanks
 

Jim@HiTek

Joined Jul 30, 2017
30
I didn't read all the responses but you don't really need a separate PS at all for LEDs. Just a 22K, 1/2 watt carbon film resistor in series with a standard 'modern' LED (older LEDs go POP) will light an LED just fine. That's for green and the resistor can be adjusted for other colors. No reverse diode needed, for green anyway. I'm looking at 6 of them glowing, wired up that way right now in a many year old power distribution center. Dunno about the flicker you need though. Trying to think of an AC circuit with a triac, a pair of N-Chan FETs driving it and a dual RC timer circuit. All 120 volt operation so the need to for an extra PS goes away.

Also, there are Tea Lights available for a few cents that have the LED flicker built in, so they look like a flickering candle...but they use 1.5 volt button batts. Could be jury rigged for your purposes to operate on 120 Vac though.

Just spit balling here.
 

MisterBill2

Joined Jan 23, 2018
9,028
Any LED device claimed to be suitable for mains application will include a power supply circuit of some kind, and that will certainly be a highly stressed part of the system, subject to failure. And attempting to operate any LED from mains voltage using only a current limiting resistor seems like a very fast way to produce scrap and toxic smoke.
LED reverse voltage limits are quite non-forgiving if they are exceeded.
So I wonder just what "modern" LEDs are referenced in post #23.
 
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