最近ではLEDの代わりにネオンインジケータランプを使用する理由はありますか？

古いACデバイスから回収され、電源の状態を示すために使用される古いネオンインジケータランプがたくさんあります。

私は不思議に思う：最近ではLEDの代わりにネオンランプを使用する理由はありますか？まだ広く利用可能だと思います。

LEDは、ACアプリケーションでのダイオードの必要性を考慮した後でも安価です。ACアプリケーションでは半分の頻度で点滅しますが、ワットあたりの発光量ははるかに多くなります。

どのような場合に、ネオンインジケータランプがまだ好ましいですか？

ネオン電球は、ACラインから直接ドロップ抵抗を介して供給される場合、マイクロアンペアの電流を使用します。LEDは10倍から100倍の電流を必要とし、ACに直接給電することはできません。

ネオンは、ESD、過渡過電圧、高温に対する耐性が高いことがわかると思います。

ネオンランプ回路で多くの興味深いことができますが、それらはすべて2019年の好奇心です（EMP耐性が必要な場合は役に立つかもしれませんが、それが要因である場合、より大きな問題が発生するでしょう）。一つには、ネオンがすり減っています。上記の文書から：

私が若い頃、私はLinotypeマシン（はい、その昔）のモニターシステムを設計し、ネオン電球オシレーターを使用して当時の新しいC106 SCR（0.05インチの公称幅のリードを持つ恐ろしいパッケージ）をトリガーし、熱電対を多重化する貴金属接点付きステッパーリレー。

ネオンをインジケーターランプとして使用するために数ペニー節約する以外、本当の理由はわかりません。NE2Hは約2mAで動作し、まともなLEDからより多くの輝度を与えるのに十分です（ただし、パッケージ化されたすべてのインジケータがまともなLEDを使用するわけではありません）。ネオンは、常時電源が供給されていると摩耗します（定格寿命は12,000〜25,000時間で、年中無休で3年未満です）。

BigCliveによるこのビデオをご覧ください。LEDを使用して同じ（ランダムな）光効果を得ようとすると、ライト効果（ビデオの終わりに向かってスクロール）が非常に複雑な回路を必要とします。 。

これは使用される回路です：

これはネオンランプの「キラーアプリケーション」ではなく、もっと楽しいプロジェクトだと認めています。

EEの答えではなく、美学。

LEDがいように見えます。ネオンライトは黄色オレンジ色のスペクトルでより多くの帯域を占有しますが、LEDにはわずかなスパイクしかありません。LED電球のスペクトルに関するこのQ＆Aを参照してください（ヒント：蛍光体でコーティングされたレンズを備えた単なる青色LEDです）。

ニキシー管は単なるランプではありませんが、電圧計や周波数カウンターなどのさまざまな技術機器で使用されていた50年代の人気のあるディスプレイでした。復活は、そのユニークでビンテージな外観に一部起因しています。DIYの愛好家がビンテージディスプレイを作る例がたくさん あり ます。

ヘルバス[CC BY-SA 3.0（https://creativecommons.org/licenses/by-sa/3.0）]

機器が主電源であり、利用可能な低電圧DCがない場合、ネオンははるかに簡単です。Dave Tweedが言ったように、一つには抵抗器を小さくすることができます。ネオンは、奇数の電圧サージやその他の仕様外の条件にも耐えることができます。LEDは、その機能に必要な繊細で小さな構造を持っています。ネオンは単なるガスと2ビットの銅です。

主電源専用のやかん、ラジエーターなどは、通常ネオンを使用します。それがEbay / Amazonからの安いごみであれば、彼らはそれがより安いLED cosを（ab）使用するかもしれず、彼らは信頼性を気にしません。しかし、なぜ彼らはいつも青を選ぶのですか？

The need for neons can be related to the industry. For example, equipment that wears out in nuclear facilities must typically be replaced with identical gear, because the cost of qualifying new equipment to operate in the system is so great that it makes no sense to use anything but the old design. If the old design had neons, the replacement typically will too.

The need for neons can also be cosmetic. I build nixie tube clocks for friends and use neons for the colon separating hours and minutes. The color closely matches the color from the nixie filaments, and LEDs just wouldn't look as good.

They also have very low current draw and so are sometimes used as indicators in older designs in emergency power or ride-through applications.

Have you actually tried building mains neon vs LED indicators? I bet you haven't.

Here, try a project. Sometimes, a leg of split-phase or 3-phase AC power will drop out at the poletop. Either neutral gets lost, causing L1 to rise and L2 drop, or a leg is lost, causing L1 to be backfed through 240V appliances. Make a very useful gadget that grabs L1, L2 and N, and visually indicates whether L1-N and L2-N are very coarsely the same voltage, and L1-L2 is coarsely 2x the others. The user switches off breakers and watches to see if that affects brightness one to the other. Having 3-4 lights and having the user watch for differences in brightness is fine. Durability a million hours. Needs to be simple and very low parasitic load, energy budget 720mW (3ma). Go.

However, your point is fair that 99% of electronics innovation is done on the low-voltage side of the wall wart. Neon has no place there; it would need an active circuit driving it, and that compares disfavorably with LED.

Neon and LED are different indicator types for different regimes of electricity. When you argue against neon, you're arguing against mains voltage as a supply source. As a big fan of houses having low voltage DC systems so they can happily exist in power-out situations without generators or inverters -- I can't really disagree.

Most regular LEDs have about 2 Vdc drop in forward mode and need about 1 mA to light up. although 10 mA is recommended with standard LEDs.

In addition, they can only withstand about 2 Vdc in reverse mode, which means that they need a rectifier diode in series to protect them when the ac voltage changes polarity.

In this configuration, the LED lights up only half of the time, which may reduce its brightness; this could be good or bad depending on the application.

Neon lamps use a 100 K to 250 K, 1/4 W resistor (see http://www.farnell.com/datasheets/57560.pdf).

Neon lamps are not that bright and in certain applications may not stand out when lit, especially in highly lit areas.

With time, neon lamps develop flickering and electrode polarization (only one of the electrodes glows).

Neon lamps are available in various base sizes (see https://www.bulbtown.com/neon_lamps_and_light_bulbs_s/909.htm). Some even come with an internal resistor sized for a specific operating voltage.

The current requirements of a Neon are low enough that they can generally be driven directly from the mains with a simple and cheap series resistor.

If you try to drive a LED in a similar way you have at least two problems.

• The reverse breakdown voltage is nowhere near high enough to withstand mains voltages, so you end up having to add another diode (potentially another LED) in inverse-parallel.
• Substantially more current is needed, say 10ma or so which is enough to make a resistive dropper consume unconfortbally large amounts of power. You can solve this by using a a capacitive dropper instead but capacitive droppers have their own issues which require extra components to mitigate.

So neons tend to win out in "pure mains" applications, things like indicators on sockets, plugs, power strips, wall switches, surge protectors, heaters with simple electromechanical thermostats and so-on.

If a device is intelligent enough to have a microcontroller on it then LEDs generally win out.

Several answers have already discussed the technical reasons, but they don't discuss the applications where those reasons would apply.

A lot of times, you'll see Neon indicators in industrial-grade machinery, for three reasons, two already mentioned:

1. Cheaper / easier to drive directly from main voltage (this is important as main voltage rises, like 480V 3-phase systems);
2. When under-driven, lifetime is extended substantially;
3. Simpler installation and circuitry (you can run neons directly off 480V / 277V AC with proper resistors);

As a result, industrial applications using these higher-voltages (note that ANSI still considers 480V a "low-voltage") can save power and cost with appropriately sized neon's. (Sure, it's minimal savings, but typically you need a reason to change something, not keep it the same.)

There are some other curious aspects of industrial systems that generally hold true as well:

• A lot of the logic is 24V DC or 24V AC using relays instead of transistors, easy to drop neons right in;
• The logic often activates raw 480V AC (or 277V AC) equipment -- again, easy to drop a neon in;
• Safety is always a critical issue, because these are often large, dangerous pieces of equipment, so if the bulb dies there should be a possible backup -- once again trivial with neons;
• Industrial equipment is generally expected to take a less-skilled person to service it than smaller electronics (like computers, etc.) -- neons have very common hot-swap plugs on them (LED's are often soldered);
• Industrial equipment may not even have a DC line! -- this means you have to rectify the AC for every LED;

When these aspects are considered, it should make it easier to see why a good chunk of (especially older) industrial-grade equipment would prefer neons to LED's. Especially when considering that if a neon "dies", it's often just extremely dim (vs. completely off as an LED typically is) so it still has minimal functionality.

As an example and anecdote, when I was building the glass manufacturing machines, one feature our machines had was that when plugged in, there was an indicator system that told you if the 480V outlet you plugged into was wired properly. It was extremely cheap to build with Neon's (a few lights and resistors), but would have been slightly more costly (and complex) to build with LED's. (Sure, considering the cost of the machine it was barely noticeable so who cares, but we had no reason to use LED's there and this system has been used by the company for decades, so why spend extra time and money designing a new one?)

Source: I used to maintain and build industrial machinery for a plastic injection molding facility, and a glass machine manufacturing facility.

I remember using neon indicator lights as crude, inaccurate, but simple voltage references.

The reality is that in today's electronics there are not the voltages present for neon operation. And there are for LEDs.

This is a very niche use, but some neon lamps can be used as logic elements due to the voltage difference in the striking vs maintaining voltages.

You can read about somebody using this, rather than a microcontroller, to control a clock:

• http://www.pa3fwm.nl/projects/neonclock/
• https://hackaday.com/2014/09/29/a-nixie-clock-with-neon-bulb-logic/