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Old 24th November 2015, 21:29   #5716
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The electronics differs totally. You can buy a neon pilot lamp, break the housing and then use it.
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Old 24th November 2015, 22:01   #5717
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Thank you. Now I know what it is! Can I replace it with an LED bulb somehow? Not sure where I'd find them.
You may try fixing an LED with a 100K resistor. It should work in my opinion. Expert's comments always welcome.
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Old 25th November 2015, 03:43   #5718
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I suppose this pilot light must have one leg to live, and one to neutral. The consequences of getting it wrong could be unpleasant. I don't think trial and error would be good here.
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Old 25th November 2015, 07:54   #5719
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Can someone help me with what this bulb is called? This is a green color bulb that conked off in our water heater recently - I've not been able to find these in the usual electrical shops.
Back in the good old days I used to get these bare neon lamps in red and green color in the electronics market. They used them in all electrical goods as a power indicator. Lately, they are not available bare but you will still get them as panel indicator lights in the electronics shops. Just pull the lens of the assembly and you will be able to get the neon lamp out. They do not cost much either.

Last edited by techiecal : 25th November 2015 at 07:56.
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Old 25th November 2015, 09:43   #5720
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Originally Posted by hellmet View Post
Thank you. Now I know what it is! Can I replace it with an LED bulb somehow? Not sure where I'd find them.
A LED requires a lot more components for such a simple job. Getting a neon bulb shouldn't be much of a problem. Or ask for a neon mains indicator from an electrical shop and remove the neon indicator and its series resister from the plastic unit. You can source one from here: https://www.industrybuying.com/indic...SW.IN5.414160/

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I suppose this pilot light must have one leg to live, and one to neutral. The consequences of getting it wrong could be unpleasant. I don't think trial and error would be good here.
These neon gas bulbs are not polarized unlike semi conductors. As long as you have a current limiting resister in series which restricts the current, they are happy to lead a long life.

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You may try fixing an LED with a 100K resistor. It should work in my opinion. Expert's comments always welcome.
LEDs are good in a low voltage DC application and when connected directly across the AC mains, they tend to fail unless you use an elaborate circuit.

Sorry about the back to back posting.

Last edited by Gannu_1 : 26th November 2015 at 08:48. Reason: Back to back posts merged. Please use the multi-quote feature (QUOTE +) to quote and respond to multiple posts.
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Old 25th November 2015, 18:08   #5721
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These neon gas bulbs are not polarized unlike semi conductors. As long as you have a current limiting resister in series which restricts the current, they are happy to lead a long life.
It would be getting the resistance right that would worry me. Could they explode if overpowered?
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Old 25th November 2015, 18:30   #5722
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Could they explode if overpowered?
Nope, they will heat, to an extent that it will melt plastic.

Since we're taking about a single LED here, even the basic quarter watt resistor will suffice and wont cause heat issues.
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Old 25th November 2015, 18:49   #5723
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It would be getting the resistance right that would worry me. Could they explode if overpowered?
The original NE2 would be good to sink up to 20 mA and here we barely pass about one milliampere with a 150k series resister.

These neon gas tubes work like this:
Until a predetermined voltage across their terminals occurs they are open (not conducting). Once their threshold voltage occurs, the gas starts conducting and presents a low resistance across the terminals. This can be useful in many applications : Surge arresting, voltage stabilization to name a few.
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Old 26th November 2015, 08:35   #5724
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Resistance value barely matters as long as it is 120k or more. I used 270k - slightly lower brightness, but that barely mattered.
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Old 26th November 2015, 14:50   #5725
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Can someone explain to a layman (me) why is it advisable to use a surge protector than a voltage stabilizer with a TV.

Using a time-delay stabilizer makes sense for something like a fridge because we don't want the compressor starting stopping starting in a difference of 1 or 2 seconds but why wouldn't a stabilizer protect the TV from low voltage and high surges?
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Old 26th November 2015, 16:04   #5726
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Can someone explain to a layman (me) why is it advisable to use a surge protector than a voltage stabilizer with a TV.

Using a time-delay stabilizer makes sense for something like a fridge because we don't want the compressor starting stopping starting in a difference of 1 or 2 seconds but why wouldn't a stabilizer protect the TV from low voltage and high surges?
Modern TV (as well as a computer) uses a Switch Mode Power Supply (chopper power supply) which 'transforms' the AC mains input at 240 V in India at 50 Hz/220 V in Europe/ 110 V at 60 Hz in the USA to lower DC voltage using high speed semiconductor devices operating at higher frequencies for better overall efficiency as well reduction in size.

As a result, these TVs can operate from about 110-240V without any external assistance. A relay based stabilizer - the kind you use for Airconditioners and Refrigerators tends to chatter at some voltage levels and don't switch fast enough to the next level - resulting in momentary over voltage. This causes transients in the supply to sensitive semiconductors which may breakdown. A surge protector has no moving parts like a relay or any inductive component like a transformer to cause any transients. Thus it is safer to use a well designed surge protector than a simple stabilizer.

A metal oxide Varistor (MOV) in a surge protector shorts the supply at its designated voltage protecting the devices downstream from any over voltage, line transients and lightening surges. They can pass high currents from 20 A to a lot more when they start conducting tripping a MCB or a fuse before the device. They are usually padded with suitable capacitors to bypass dangerous RF transients.
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Old 26th November 2015, 17:01   #5727
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Default Re: The Home Appliance thread

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Originally Posted by fine69 View Post
Can someone explain to a layman (me) why is it advisable to use a surge protector than a voltage stabilizer with a TV.

Using a time-delay stabilizer makes sense for something like a fridge because we don't want the compressor starting stopping starting in a difference of 1 or 2 seconds but why wouldn't a stabilizer protect the TV from low voltage and high surges?
Voltage stabilizers have a reaction time that is longer than the duration of a surge (which are of milli/micro second duration). By the time they can react & stabilize the voltage, the surge would have passed through to the connected devices and destroyed them.

Hence, it is better to have a surge protector first. It can be followed by a voltage stabilizer in the circuit.

This is the most plausible explanation that I could find after searching a lot on the internet. Makes sense as well to an electrical engineer like me.
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Old 26th November 2015, 17:16   #5728
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Default Re: The Home Appliance thread

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This is the most plausible explanation that I could find after searching a lot on the internet. Makes sense as well to an electrical engineer like me.
Thanks for the post. Can you please do us a favour of posting a link of one such surge protector being sold online. Would like to have it to protect my analog rig. Please do it in leisure.

Thanks.
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Old 27th November 2015, 08:21   #5729
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Bought this microwave from Amazon. Ordered on Monday and received it yesterday. Pretty good service

Overall happy with delivery time. Hope the product works as per the user reviews
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Old 27th November 2015, 10:26   #5730
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Default Re: The Home Appliance thread

Quote:
Originally Posted by fine69 View Post
Can someone explain to a layman (me) why is it advisable to use a surge protector than a voltage stabilizer with a TV.

Using a time-delay stabilizer makes sense for something like a fridge because we don't want the compressor starting stopping starting in a difference of 1 or 2 seconds but why wouldn't a stabilizer protect the TV from low voltage and high surges?
Voltage surges are of very short duration - milliseconds so they rarely burn normal electrical gadgets - irons, bulbs motors. The voltages are high at times going beyond 1000V. For electronics that is death.

Surge protectors "Blow" very fast isolating the downstream circuits. In contrast voltage stabilizers are slow with reaction of few tenths of a second at the most. By the time they react to the surge voltage, it has passed through and done its damage.

As most of the appliances today (TV, AC, Refrigerators, MW etc) have electronics for control and optimum operation, a surge protector will protect them against failure of the "Mother Board".
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