Mains indicator LEDs

[JohnD]

I have several Crabtree switches with indicator neons that have gone black. I can still get replacements, but I'm hoping there is a source of LEDs that will last longer and perhaps be brighter.

The neons have an integral resistor and long tails, "bulb" is 6mm diameter and about 20mm long

Does anyone know a source?

Thanks in advance

 

[DetlefSchmitz]

Well, it's this kind of thing:

L295000MAA ​

ARCOLECTRIC (BULGIN LTD)​

Different prices from different suppliers, and always a gamble if it will fit. Type the name into google to see it.

 

[JohnD]

Ah yes, that 's a panel lamp, not quite what I need.

Thanks

 

[JohnD]

It's to go in these, to fit in clips behind the windows

 

[DetlefSchmitz]

Yes, I bought something like this for an indicator for my boiler wiring centre, and you could pull out the led from the mount, but there's no guarantee. Sorry, I just looked for one of them to see but it has long disappeared.

 

[FrodoOne]

Suggest
LED "selection"
https://www.aliexpress.com/item/1005005708510866.html?spm=a2g0o.productlist.main.5.cb75b601eVgCdX&algo_pvid=b86b0040-cd5a-418d-86c1-b28943a651c9&algo_exp_id=b86b0040-cd5a-418d-86c1-b28943a651c9-2&pdp_npi=4@dis!AUD!3.60!3.60!!!16.80!16.80!@2101c72a17232669878772820ee461!12000034078716879!sea!AU!3729617017!X&curPageLogUid=R62RPcvWwD3Z&utparam-url=scene:search|query_from:
or

100pcs 3mm LED Diode F3 Assorted Kit White Green Red Blue Yellow Orange Pink Purple Warm White DIY Light Emitting Diode - AliExpress 502

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

plus
Diode

100pcs 1N4004 4004 1A400V DO-41 GENERAL PURPOSE PLASTIC RECTIFIER New Original - AliExpress 502

Smarter Shopping, Better Living! Aliexpress.com

www.aliexpress.com

plus
1/2 W Resistor (47K - or higher)
and
DIY.
(Total cost - Less than £5 - with many "spares" !)

 

[DetlefSchmitz]

Suggest...

I was going to make a similar suggestion, but there is a lot more than basic Ohm's Law involved in connecting components directly across the mains, and plenty of scope for making something dangerous. One thing is voltage ratings of resistors. Also, I suspect that 4k7 would put rather more current through the led than a modern led actually needs as they have got a lot brighter through the years. And would dissipate more than 10W.
Not saying don't do it, but some care is required.

 

[JohnD]

The plain LEDs are all around 3V, I suppose.

There must be a market for mains voltage indicators, you see them everywhere in appliances and switches..

 

[SFK]

Instructions and warnings here by bigclivedotcom:

 

[333rocky333]

You asked similar in 2017 and at the time mk still sold there neons, maybe now they also have an led version.
It may be easier to find a brand that does use leds and remove from an accessory.
We replace a lot of damaged bg sockets, they have a light on.
Next time I do one I will break open and see if its led.
A twin bg is about 4 pound and give you 2 if they are led or if you can wait I could possibly post you some.

 

[DetlefSchmitz]

A twin bg is about 4 pound and give you 2 if they are led

That's certainly cheaper than just the commercial mains led indicators I have seen.

 

[333rocky333]

Looking at there Tech spec on TLC seems they still use neons, will break one open soon get some pics

 

[JohnD]

You asked similar in 2017 and at the time mk still sold there neons, maybe now they also have an led version.
It may be easier to find a brand that does use leds and remove from an accessory.
We replace a lot of damaged bg sockets, they have a light on.
Next time I do one I will break open and see if its led.
A twin bg is about 4 pound and give you 2 if they are led or if you can wait I could possibly post you some.

Very kind offer, thank you.

I can get the neons but was hoping for LEDs.

 

[FrodoOne]

I suspect that 4k7 would put rather more current through the led than a modern led actually needs

Correct.
I should have written 47 K - to give 5 mA at 240 V

Since the current flows only each half-cycle, the "equivalent current" would then be only about 2.5 mA
However, the rating of the 1/2 Watt resistor would be exceeded.
Hence, the minimum 1/2 W resistor valuewould be 120 K.

 

[briwire]

I've always works to the figures that LEDs need 3v at 10mA, they do vary so have a look at the data sheets. So you will be dropping say 237v. 237/0.01=23700 ohms. You could get away with a 22000 ohm resistor but it must be rated about 250v, so quite bulky.
The power dissipated is 0.01 squared X 22000=2.2watts. So your resistor would have to be 3-5w minimum.
LEDs also operate on DC, so you would need to rectify the AC with a diode, which would give a half wave effect, dimming the LED a little.
Bottom line is, buy a ready made 240v AC indicator, there may be some small enough for your application.