Have successfully converted xmas accessories like a tree top angel from old incandescent bulbs to leds using discrete components by doing some math but am not seeing a clear way to modify these simple one scr ldr night light circuits simply because the led bulbs are an unknown ... does anyone have a simple solution to reusing these devices with led bulbs? Or know how to model these 7W Led bulbs to do calculations

 

WHAT??? What does " one scr ldr "mean, in common words??? It tells me absolutely nothing at all.

 

Yes please, SCR Ldr ? What's the voltage for the 7W LED's and how many of them in the string.

 

First pick the LEDs and their color. Then go from there. If this is a night light you don't really need a lot of brightness.

 

Have successfully converted xmas accessories like a tree top angel from old incandescent bulbs to leds using discrete components by doing some math but am not seeing a clear way to modify these simple one scr ldr night light circuits simply because the led bulbs are an unknown ... does anyone have a simple solution to reusing these devices with led bulbs? Or know how to model these 7W Led bulbs to do calculations

I am assuming that 'ldr' is light dependent resistor? I am also assuming you are using a standard bulb as opposed to your own arrangement of LEDs and driver? Does the circuit use an SCR or TRIAC? If it is an SCR then the half wave rectification may be the issue. If it is a TRIAC then it may just be an issue of triggering (esp in the troublesome 3rd quarter).

Is the idea that the bulb should dim, or is it an on / off function only?

There are fundamental differences between the start up characteristics of incandescent globes compared to LED globes. Incandescents initially draw a current several times greater than their steady state current and LED globes also draw an initial spike but the LED spike is shorter lived (that is an extrapolation on what I know so don't take that as gospel or a universal rule).

Depending on your answers to the above questions, there are things you can try that might help define the cause of the issue. The first and easiest experiment is to add a load to help 'latch' the SCR. This could be an incandescent bulb or a series RC in parallel to the load. If it works ok then,your issue is latching the SCR. If the incandescent bulb works but the led does not when they are both simultaneously connected as loads then I would suspect your control circuit is providing only half wave through. This could happen even if it is a TRIAC. That trouble some 3rd quarter may not be triggering.

FYI, the typical LED bulb input stage is a simple resistor / tiny NTC, diode bridge and smoothing cap (although I have seen LED controllers for offline use where they have a buck converter running directly from rectified mains with no smoothing cap,only EMI filter caps.) A dimmable bulb will almost definitely have the smoothing cap as they sense the mains conduction angle and dim accordingly, so the dimming control is a function of the bulb based on the dimmer command (conduction angle).

The ball is now in your court

 

WHAT??? What does " one scr ldr "mean, in common words??? It tells me absolutely nothing at all.

Perhaps then, the question is not for you.
When a person posts a question hoping for assistance, how much knowledge should they assume in their audience? If you assume the OP is reasonably intelligent and has not used bizarre acronyms, then maybe you lack the specific knowledge they require. In which case, if you wait to see how the thread develops, you might add something and learn something too and feel good for both things. The primary aim of sharing knowledge will have been met.
Aggressive responses will simply deter people posting anything.

 

Yes please, SCR Ldr ? What's the voltage for the 7W LED's and how many of them in the string.

They did say 'bulb' and they also asked for electrical details of the 'bulbs'.

 

Perhaps then, the question is not for you.
When a person posts a question hoping for assistance, how much knowledge should they assume in their audience? If you assume the OP is reasonably intelligent and has not used bizarre acronyms, then maybe you lack the specific knowledge they require. In which case, if you wait to see how the thread develops, you might add something and learn something too and feel good for both things. The primary aim of sharing knowledge will have been met.
Aggressive responses will simply deter people posting anything.

You need to understand that folks post on these forums from all over the world, and unfortunately I am not a master of many languages. In addition, from my long career dealing with folks who need problems solved, I have learned to ask rather than assume that I know what every term they use means. Faking that one understands the intended meaning of every bit of jargon is a good way to get into expensive misunderstandings.
Besides all of that, it really makes sense that anyone asking a broad spectrum of folks for help is better off using clear words instead of acronyms and jargon.

The fact that somebody is able to string them together and hide the meaning from me does not mean that either of us is unqualified, but rather that we do not speak the same language.

 

SCRs are used to reduce the power from AC to a load Have you thought about using a 5V USB power cube instead? It's a lot safer and easier.

 

You need to understand that folks post on these forums from all over the world, and unfortunately I am not a master of many languages. In addition, from my long career dealing with folks who need problems solved, I have learned to ask rather than assume that I know what every term they use means. Faking that one understands the intended meaning of every bit of jargon is a good way to get into expensive misunderstandings.
Besides all of that, it really makes sense that anyone asking a broad spectrum of folks for help is better off using clear words instead of acronyms and jargon.

The fact that somebody is able to string them together and hide the meaning from me does not mean that either of us is unqualified, but rather that we do not speak the same language.

I am not trying to persecute you or even to be impolite in any way. I am only trying to help you see how your response was not ... kindly or friendly but a little inappropriate to be honest and IMHO.

In this case I do not think this was a language issue, just a vernacular issue. And my point is made in your 2nd sentence, posters are 'asking for help' more than 'needing you to solve their problems'. There is a subtle yet very real difference in the attitudes that adopt each of those contexts. One is a desire to help and the other is plain narcissistic (not to put too fine a point on it).

I fully understand and appreciate your policy of asking questions and I am fully on board with, and applaud you're not faking knowledge. Faking knowledge leads to misinformation and not so much the sharing of knowledge but the sharing of ignorance.

I am not sure how misunderstandings become expensive in the context of an enthusiasts website and forum but I do back your point that if an acronym is unknown to you, ask for an explanation which can do no harm and may do a lot of good for everyone. I make the further point though, that if an acronym is unknown to you that does not mean it is unknown to everybody and it might mean the question is outside your area of expertise. To assume otherwise, to assume you are more learned in the topic than the OP, you just don't know the acronyms they are using bespeaks an arrogance that is very unattractive

Again, I am not trying to have a go at you. Read your response again and see if you cannot understand what I am saying.

If the OP simplified the question as you suggest then that would mask their level of mastery in the topic and would likely lead to grossly insulting responses, possibly from posters who know less than they do.

I think the question was fine and your stated policy of asking questions to clarify things is the perfect response especially if you feel you may have something to contribute. Your actual response though did not ask any questions, used aggressive language and ended with an exclamation mark. In short, it was somewhat abusive. Which is why I suggested perhaps you should just skip over posts that provoke this kind of response from you or just wait and watch how the thread develops.

These forums are at their best when people with questions are not afraid to ask them. If, in their timidity, they have phrased the question in a way that is not to another individuals liking, an unfriendly response is the exact opposite of helpful. You may or may not agree with that.If you agree but with caveats then you have missed my point entirely.

Perhaps I should take my own advice and just skip over posts I find provocative or confronting.... hmmm.

 

This may be a little off the main thrust of this thread, but adding a light controlled switch to a nightlight is really a waste of time and other resources.

Given the low power and long life of (most) LED night lights, the low annual operating cost is hardly not worth the effort, let alone cost, of adding any circuitry at all. The on/off switch on commercially available LED night lights is merely there for the emotional comfort of the prospective customers.

 

Misunderstandings in my realm of industrial machines are where things can get into expensive misunderstandings. I observed that a few time in my career. The most expensive instance was when my employer was asked to bid on a project system that we had bid on once but was built by a competitor with a much lower bid. The "misunderstanding" was the competitors assumption that +/- 5% accuracy was adequate for the application. It was not! The expensive part was that the competitor had to eat that cheaper machine cost. It was not accepted.

 

Every field is rife with acronyms.

The advent of smart phones has caused the proliferation of shorthand texting. I am no big fan of textese and will never use BTW, AFIK, IIRC, TTFN, TIA, LOL, etc.

In electronics and in AAC forums, there is general acceptance of common acronyms such as LED, AC, DC, MCU, ADC, DAC, TTL, CMOS. We all must recognize that here on AAC forums, members come with a wide range of electronics background from zero to retired expert. Hence, if you are going to use a less widely known acronym then please spell it out on the first-time usage.

What the heck is CPDLC?
https://forum.allaboutcircuits.com/threads/cpdlc-modification.186243/

On the other hand, if you don't know the meaning of an acronym, it is ok to ask or look it up yourself.

Sometimes there is country of domicile or language differences. For those, we have posted this:
https://forum.allaboutcircuits.com/...-acronyms-and-synonyms-in-electronics.194725/

Just yesterday I had look up the meaning of <3. I thought that it was making reference to the female anatomy! You learn something new everyday.

Call me old school.

 

The reality is that not everybody is familiar with everybody else's acronyms all the time.

AND, is it really that much extra effort to spell out the whole set of words?? When I ask for advice, suggestions, or actual help, I try to let those I am asking know as much as the whole name of what I am looking for.
When folks ask for advice about a model number of some sort of system or appliance, consider that some others may have experience with something very similar, and that what they learned may be quite useful.

 

When I started in electronics LDRs were called CdS cells, times change which is one reason acronyms are not necessarily the best things to use. Here was what I was trying to describe earlier schematics are the language of electronics you're not familiar with them you will need to get used to them if you wanna use electronic components:


While not a given for any particular LDR they can very a couple of ohms in the light to a couple of mega ohms in the dark. You can verify this with an ohm meter.

 

The funny "night lights" are the really old ones with the small neon bulb, that stop lighting in the dark, but just the beam from a flashlight will get them glowing.
The explanation is that the extra energy from the external light allows the neon to ionize and conduct for the glow.

 

This may be a little off the main thrust of this thread, but adding a light controlled switch to a nightlight is really a waste of time and other resources.

Given the low power and long life of (most) LED night lights, the low annual operating cost is hardly not worth the effort, let alone cost, of adding any circuitry at all. The on/off switch on commercially available LED night lights is merely there for the emotional comfort of the prospective customers.

Every field is rife with acronyms.

The advent of smart phones has caused the proliferation of shorthand texting. I am no big fan of textese and will never use BTW, AFIK, IIRC, TTFN, TIA, LOL, etc.

In electronics and in AAC forums, there is general acceptance of common acronyms such as LED, AC, DC, MCU, ADC, DAC, TTL, CMOS. We all must recognize that here on AAC forums, members come with a wide range of electronics background from zero to retired expert. Hence, if you are going to use a less widely known acronym then please spell it out on the first-time usage.

What the heck is CPDLC?
https://forum.allaboutcircuits.com/threads/cpdlc-modification.186243/

On the other hand, if you don't know the meaning of an acronym, it is ok to ask or look it up yourself.

Sometimes there is country of domicile or language differences. For those, we have posted this:
https://forum.allaboutcircuits.com/...-acronyms-and-synonyms-in-electronics.194725/

Just yesterday I had look up the meaning of <3. I thought that it was making reference to the female anatomy! You learn something new everyday.

Call me old school.

Have we lost the thread a bit here?

 

When I started in electronics LDRs were called CdS cells, times change which is one reason acronyms are not necessarily the best things to use. Here was what I was trying to describe earlier schematics are the language of electronics you're not familiar with them you will need to get used to them if you wanna use electronic components:

View attachment 340652
While not a given for any particular LDR they can very a couple of ohms in the light to a couple of mega ohms in the dark. You can verify this with an ohm meter.

Topic?

 

The funny "night lights" are the really old ones with the small neon bulb, that stop lighting in the dark, but just the beam from a flashlight will get them glowing.
The explanation is that the extra energy from the external light allows the neon to ionize and conduct for the glow.

Topic?

 

Have successfully converted xmas accessories like a tree top angel from old incandescent bulbs to leds using discrete components by doing some math but am not seeing a clear way to modify these simple one scr ldr night light circuits simply because the led bulbs are an unknown ... does anyone have a simple solution to reusing these devices with led bulbs? Or know how to model these 7W Led bulbs to do calculations

It seems your 'scr ldr' has caused this whole thread to derail. I recommend you start again with a new thread. Also make sure you make the point that the load is a 7W led BULB because they also seem to have missed that point entirely as well.
Good luck.