Sometimes it is necessary to find out the presence of mains voltage, or, for example, to identify a switch in the dark. The simplest indication element is a small neon lamp, which can be directly connected through a resistor to a 220 V network, consumption will be minimal, and the effect will be achieved. Yes, in modern conditions, LEDs are much more popular, but they require more wiring for such purposes, which is why neon bulbs are still successfully used in industrial devices (irons, kettles, etc.). Under the cut there will be a construction of a stand for testing 220 Volt devices (as safe as possible) and a bit of my balcony, which I equipped for creating crafts...
Neon lights came without a track, I found them in mailbox. The parcel arrived for about a month and a half. Inside the bag with a built-in bubble wrap were light bulbs with soldered resistors in a Zip lock bag: 
The quantity corresponds to the declared one. Type and dimensions of one copy: 
The resistor is set to 147 kOhm: 
We try to connect to a 220 Volt network: 
More precisely 230 :) 
This socket does not detect low currents: 
Let's connect a multimeter that records a current of 1.2 mA: 
About the neon lights themselves. The light of the lamp has low inertia and allows brightness modulation with a frequency of up to 20 kHz. The lamps are connected to the power source through a current-limiting resistor so that the current through the lamp is about 1 milliampere. Using a lamp without a resistor is extremely dangerous, since it can lead to the discharge developing into an arc, with the current through it increasing to a value limited only by internal resistance power source and supply wires, and, as a result, short circuit and/or rupture of the lamp cylinder. The lamp ignition voltage is usually no more than 100 volts, the extinction voltage is about 40-65 volts. Service life - 80,000 hours or more (limited by gas absorption by the glass of the bulb and darkening of the bulb from sprayed electrodes; there is simply nothing to “burn out” in the lamp).
Now to the application... Actually, I ordered them to replace the standard light bulb in an old iron that I use for making circuit boards. But since we have a lot of them, it would be a sin not to use them.
Considering that I quite often test devices operating with mains voltage, I decided to assemble a test stand. Basic requirements:
- safety, after all, these are crafts and anything is possible on the table during tests;
- convenient connection of your devices (socket);
- indication of current current and voltage, as well as power consumption;
- for testing switching devices, a separate socket with a wire and, preferably, with an indication;
- the ability to disconnect both power wires of the device;
- minimal influence of wires on the processes under study;
- more or less decent appearance and compactness.
To increase the safety of the device, I decided to install a category “C” differential circuit breaker of 10 A, with a leakage current of 30 mA. And once we're talking about about an automatic machine, it is more convenient to use a compact shield, especially since they are inexpensive. I chose as an indication, it satisfies all my requirements (80-260 V/20A AC), reviews of this device have already been on Muska (,). I decided to build this device into a compact panel: 
To connect power to my stand I used a standard C14 connector: 
I decided to place it on the side and cut a hole for it: 
I secured it with screws from a disassembled microwave. Assembled: 
Soldered wires: 3 x 2.5 mm2, insulated contacts with adhesive heat shrink: 
The socket for connecting the devices under test was mounted on a DIN rail. Assembled device: 
We check: 
But this didn’t seem enough to me... Quite often you have to test a switching node, so I wanted to combine the interface for connecting loads with this device. A standard socket is suitable for this; I took it from Schneider Electric (it’s a little off-color, of course, but oh well): 
It is in it that it is planned to build in the neon bulbs under review. Red plexiglass was used as a light diffuser: 
This is what the light bulb looks like through it: 
Cut off a small piece with a jigsaw: 
We will finish the edge with a drill on a stand: 
Trying on glass: 
I'm satisfied, I need to drill: 
Let's try it on, I specially turned the edge obtained at home towards the base of the socket - this way it will be least visible: 
We degrease the glass and rosette with the tips from the home distillation process and glue them with superglue: 
Result: 
Next we return to neon bulbs. I was not satisfied with the length of the leads, so I resoldered the resistor: 
I prepared the wiring to connect the light bulb to the socket: 
Put on the heat shrink: 
Soldered the wiring: 
On top I put a general adhesive heat shrink of a suitable diameter: 
Result: 
Examination: 
I decided to secure it in the socket with hot glue: 
I had to come up with something to cover the rest of the space around the lamp, I decided that foil would be perfect for this, but where to get it. And then the thought came to mind about New Year's gifts hidden from the children on my workshop balcony. I had to go through quite a few candies to find the right one. It turned out that modern manufacturers are actively saving on foil. Suitable option: 
The candy was successfully eaten (may the children forgive me :)), the delicious candy gave me new strength. Result: 
Getting ready to connect the shield and our mega socket, we drill the base: 
And the side of the shield: 
The sidewall plastic is quite soft, so I decided to reinforce it from the inside with PCB (well, yes, I wrote about boards in the title). The rejected board will still work, I used the base of the socket as a template: 
Let's try: 
To prevent the screws from coming loose, I decided to use the domestic anaerobic thread locker AutomasterGel from Region Spetstechno. I reviewed this wonderful fixer: 
There is a latch different types, I used the most powerful one :). Apply it to the screws: 
Result: 
On the other side: 
Assembling the cover: 
Connecting the wires: 
I’ll say right away that I pulled with force and everything fits tightly despite the difference in diameter.
Result: 
Closer: 
Included: 
At some distance, everything is also clearly visible: 
With a lamp in a socket (this is exactly what we plan to use in many upcoming tests): 
Without light it looks like this: 
With maximum light the indicator is also noticeable: 
We are preparing the input wire for testing switching devices (PVS 2x2.5 mm2), marked it with red heat shrink: 
Assembling the fork: 
If the diameter of the wire is too large for testing the device, we use a transition to a thin wire (ShVVP 2x0.5mm2) through Vago reusable universal terminal blocks (it is in such cases that it is advisable to use them - for temporary connection). This is what the next tested device looks like, connected to the manufactured stand, immediately after cleaning the table: 
The device itself on the windowsill: 
General view of the tester's workplace:): 
The main object of testing will be spot welding boards from, and other crafts for country automation.
Illustration of the operation of the assembled structure in testing another craft:
And since the switching is carried out by a triac, this video shows the behavior of the indicator, which, when turned off, lights up less brightly, but does not go out; this feature of triacs should be remembered.
This concludes my long opus about a fairly simple, but very necessary device. Happy New Year to everyone! I hope someone this information will be useful.
Additional information
If you make an indication on an LED, the correct circuit will look like this: 
In real life: 
If you reduce the capacitance 10 times to 10nF: 
Under the influence of public opinion, I redesigned the stand :)
I replaced the socket cover with a white one to match the color of the box, drilled it into the box from the socket, and embedded a neon light holder with a beautiful piece of glass into it: 
in the dark 
in the bright light of a table lamp directed at the stand, everything is also visible: 
By the way, the stand is also perfect for testing switching power supplies; the differential circuit breaker protects against short circuits and overcurrent, as well as against problems associated with phase contact. And you can insert a light bulb into an external socket as in the review and connect the 4 wires of the device so that the phase goes through the light bulb - very convenient.
Neon lamps are the brightest new lighting fixtures that offer maximum efficiency and long term operation. Therefore, today they are used in a variety of areas of human activity, including lighting of buildings and interior lighting of premises.
A neon lamp is a glass tube filled with gas under reduced pressure.
Advantages and disadvantages
Let's consider the main advantages of lighting devices that are in demand today, such as a neon lamp:
- quite bright light effect;
- long service life - for 80,000 hours;
- lamps of various shapes can be made;
- does not heat up, which means it is fireproof;
- you can choose a device with any white backlight;
- you can control the brightness;
- it works without noise.
But it is worth considering that although such lighting is used everywhere, it also has its disadvantages:
- contains harmful substances;
- requires high network voltage, and also requires a high-voltage transformer;
- high cost.
How do they work?
A neon lamp consists of a bulb in which the following processes occur: when moving, electrons collide with neutral gas atoms, which are fillers in this area, and begin to ionize them, pushing electrons from the upper area into the container. The atoms, in turn, collide with electrons, again becoming neutral atoms. Thanks to this reverse transformation, a quantum of light energy is emitted. As you can see, the operating principle of neon lamps is not very complicated.
When turned on, such devices do not heat up much - the heating temperature reaches a maximum of 80 °C. It is for this reason that neon tubes are also commonly called cold cathode lamps. Their scope of application is quite wide, as they are durable, economical and functionally flexible. The main advantage of such light bulbs is that they can have any shape you like.
Any inert gas and metal vapor has its own spectral light composition:
- helium tubes emit light yellow or pale pink light;
- neon tubes - red light;
- argon tubes - blue light.
Application of neon strips
It should be noted that on the neon lighting market you can also find neon strips or, as they are commonly called, flexible neon. They are LED garland, sealed in a PVC tube. Flexible neons are divided into multi-colored and monotonous. They are made from high quality PVC pipes and can be either transparent or matte. Single-color options are made from matte tube.
The tape, in comparison with a light bulb, has numerous advantages, among which it is worth noting:
- there is no risk of mechanical damage. Glass lamps break very often, so they can be very dangerous, in particular if you want to decorate a nursery with them. But the tape has no such drawback;
- waterproofing;
- you can use RGB technology;
- The tape is flexible, which makes it possible to install it in almost any room or outside a building. As a result, the backlight turns out to be quite mobile;
- the tape will cost less when compared with the LED option. LED strips not a great buy in all cases.
Neon strips are quite in demand, and over time they can even push some types of lighting devices out of the market. They have a fairly wide range of light, for this reason they are widely used in various fields.
The use of neon lighting in the interior Scope of application
Both lamps and cords consisting of inert gases are used everywhere. They began to be used for:
- production of hidden lighting;
- decorative design of the external area of buildings, architectural structures, monuments and so on;
- lighting of advertising structures;
- decorating unusual interiors in any residential premises and other public places.
Neon lamps used today in home interior design look very organic and presentable. With their help, you can transform any room and add your own special touch to the decoration style. They are indispensable for organizing a picnic in the evening; you can use them to create an extraordinary atmosphere.
In everyday life, such a tape is also very valuable. She is ideal solution for illuminating the ceiling area, aquarium, as well as any cabinet. You can make sure that when you open the cabinet, the light installed in it using a neon cord automatically turns on.
The tape can also be useful in the kitchen area - if it is noticeably dark when washing dishes or preparing food. You can simply install a neon strip of the required length in the required area. And there are a huge number of such ways to use this tape.
As you can see, the scope of application of such universal lighting devices is quite extensive. This is explained by their advantages, among which it is worth noting high quality and a beautiful luminous flux. Only LED strip can compete with them.
A few days ago I came across an old neon lamp PN-1.
She gave me the idea to talk about the use of neon devices in various devices.
Despite her advanced age, she is already 60 years old, the light bulb turned out to be in good working order. I plugged it into the network through a ballast resistor and saw a characteristic orange glow.
The main purpose of neon lights was to indicate the presence of mains voltage; in this role they can still be found in switches and extension cords. Recently, they have been replaced by LEDs, which have significantly more color capabilities.
Here is another representative of neon bulbs - MH-3. She is 12 years younger, PN-1.
During my school years, I came across neon TN-0.2 from decommissioned equipment. Now they were not at my disposal, but 40 years ago I made a relaxation generator and a multiphase multivibrator using them.
By the last quarter of the twentieth century, neon women became small and graceful. The INS-1 indicator with an end glow can be considered a quite good power indicator.
I don’t know the type of this light bulb; it was made by hardworking Chinese.
And they placed it in a neat flashlight with the inscription 220 V AC.
I installed these flashlights in the input shield in one of my projects, but the quality of these network indicators turned out to be very low; after a week, the ballast resistors were charred and crumbled. I had to install higher power external resistors. It’s good that this happened before delivery to the customer.
The orange glow color of the neon was not quite suitable for indicating the normal operation of the device; it was logical to indicate normal operation with a green glow. For these purposes, the TLZ light bulb was produced.
In addition to the “two-legged” creatures, the Soviet industry also produced more complex neon products. The gas in the light bulb glows near the cathode. If you place several cathodes in the form of numbers in a flask, you will get a digital indicator. Here they are, arranged by age.
IN-14
As can be seen from this photograph, the same part was used to indicate “two” and “five”, just inverted. These indicators have been widely used in digital devices released in the 70s. The numbers were quite dim and hard to read; replacing them with LEDs made the devices much more convenient.
The idea of using neon numbers did not escape me either; many years ago I assembled a watch with IN-14 indicators. They are still alive, but not in use.
Neon lamps could not only indicate the status of the meter, they could work as a counter. Here is a photo of a dekatron - a neon counting decade.
True, the maximum operating frequency was several tens of KHz and the reduction in cost of transistors threw neon devices out of this niche. Forty years ago, during laboratory work in a circle of young physicists, I used a stopwatch on such lamps. Time counting was carried out with an accuracy of one hundredth of a second.
A very interesting IN-13 indicator.
The length of the luminous cathode column is proportional to the current of the device. I have already written about its use in my journal.
http://radist-morse.livejournal.com/18819.html
There were several other uses for neon lights. The power supplies used neon zener diodes. Here's one of them.
My parents' Aurora TV used it.
Using MTX-90 thyratrons it was possible to make counting triggers and storage devices. The memory capacity, of course, is not large: as many light bulbs as there are so many bits of information.
And the last specimen from my “museum” is a baretter
While I wanted to take a picture of how it was glowing, it burned out.
You can see a burnt wire in the lamp.
Thanks to everyone who read to the end.
Although neon lamps belong to gas-discharge lighting sources, their light emission is not at all the result of an arc discharge, unlike other types of gas-discharge lamps.
Light emission from such lamps is carried out by ionized gases. Ionization of inert gases (usually a mixture of argon + neon) is the result of the interaction of neutral atoms of a given inert mixture of a lamp with free moving electrons.
Indeed, today a neon sign is a fairly popular attribute of any outdoor advertising. Their use in this area is primarily due to the characteristics of these lamps:
Saturation, softness, brightness and pleasantness of perception of their studied light;
Wide range color temperature Sveta. Changing the shade of emitted light is realized by using colored glass or changing the composition of the gas mixture in the flask (tube). Thus, tubes filled with neon emit red, argon - blue;
Service life - in some cases it reaches 15 years (!), largely depends, of course, on the frequency of switching on and off during operation;
Finally, in the literal sense, the “flexibility” of lamps is the ability to give neon tubes almost any shape - from the desired letter of any size to the entire word.
Installation and connection of neon tubes
Selecting a device for voltage conversion. High voltage is used to power neon tubes, therefore, to convert (increase) the mains voltage, step-up electromagnetic or electronic (converters) transformers are used.
When choosing the output voltage of the transformer, the length, diameter of the tube and the composition of the gas mixture should be taken into account. The table below shows the values of the secondary voltage of the transformer, based on the length of the tube in which the working mixture is neon:
For tubes containing a standard K-4 gas mixture (75% neon + 25% argon), the secondary voltage of the transformer can be calculated using the following table:
When choosing electronic converters It should be borne in mind that, despite their greater compactness and lighter weight in comparison with electromagnetic transformers, it is better to install them indoors.
This is due to limitations in operation at sub-zero temperatures. To guarantee high-quality operation of a voltage converter installed on the street, it would be more correct to use an electromagnetic step-up voltage transformer.
Wire selection. High voltage powering neon tubes requires the use of special high-voltage wires that differ from “ordinary” ones in the thickness and composition of the insulation.
The photo shows a high-voltage wire of the PMVC brand (high-voltage installation heat-resistant wire), which has a fairly thick silicone insulation with a stranded tinned copper core (cross-section 0.5-1.5 mm2).
Installation. There are basic rules for installing neon advertising that require mandatory compliance:
It is necessary to avoid direct contact of neon tubes and high-voltage wires with metal surfaces, therefore, special standard polycarbonate holders for tubes and wires should be used;
Touching high-voltage wires to metal structures can lead to current leakage, which can cause the transformer to fail. The glow of the tubes may be uneven (flickering);
When using several transformers, high-voltage outgoing wires from them should be located at a distance of at least 0.15-0.2 m from neighboring ones;
The length of the high-voltage part of the installation (high-voltage wires) should be made as short as possible. This will reduce the risk of leakage current mentioned above;
It will not be superfluous to place high-voltage wires in a PVC pipe, especially where they pass through metal partitions;
Diagrams for connecting neon tubes through step-up voltage transformers:
Connecting transformers can be done in two ways: using a standard “classical” circuit (1) and connecting through a zero point (2):
By connecting the transformer according to scheme 2, you can achieve significant savings in high-voltage cables. If any tube malfunctions, only one section will stop working - the one in which this faulty tube is located.
However, it should be taken into account that such a connection requires the same length of neon tubes in the totality of the left and right sections of the advertising sign. In addition, the diameter of the tubes and the composition of their working mixture must also be the same.
Neon. Thoughts about neon.
Checking a high voltage transformer for neon
Schematic diagrams of simple indicators for the presence of a 220V network on LEDs, replacing old neon indicator lamps with LEDs. In electrical equipment, neon indicator lamps are widely used to indicate that the equipment is turned on.
In most cases, the circuit is as in Figure 1. That is, a neon lamp is connected to the network through a resistor with a resistance of 150-200 kioles AC. The breakdown threshold of a neon lamp is below 220V, so it easily breaks through and glows. And the resistor limits the current through it so that it does not explode from excess current.
There are also neon lamps with built-in current-limiting resistors; in such circuits, it seems as if the neon lamp is connected to the network without a resistor. In fact, the resistor is hidden in its base or in its lead wire.
The disadvantage of neon indicator lamps is their weak glow and only pink color glow, and also the fact that it is glass. Plus, neon lamps are now less common on sale than LEDs. It is clear that there is a temptation to make a similar power indicator, but on an LED, especially since LEDs come in different colors and are much brighter than “neons”, and there is no glass.
But, LED is a low-voltage device. The forward voltage is usually no more than 3V, and the reverse voltage is also very low. Even if you replace a neon lamp with an LED, it will fail due to the excess reverse voltage at the negative half-wave of the mains voltage.
Rice. 1. Typical scheme connecting a neon lamp to a 220V network.
However, there are two-color two-terminal LEDs. The housing of such an LED contains two multi-colored LEDs connected back-to-back in parallel. Such an LED can be connected in almost the same way as a neon lamp (Fig. 2), only take a resistor with a lower resistance, because for good brightness more current must flow through the LED than through a neon lamp.
Rice. 2. Diagram of a 220V network indicator on a two-color LED.
In this circuit, one half of the two-color LED HL1 operates on one half-wave, and the second on the other half-wave of the mains voltage. As a result, the reverse voltage on the LED does not exceed the forward voltage. The only drawback is the color. It's yellow. Because there are usually two colors - red and green, but they burn almost simultaneously, so it visually looks like yellow.
Rice. 3. Diagram of a 220V network indicator using a two-color LED and a capacitor.
Figures 4 and 5 show a circuit of a power-on indicator on two LEDs connected back-to-back. This is almost the same as in Fig. 3 and 4, but the LEDs are separate for each half-cycle of the mains voltage. LEDs can be either the same color or different.
Rice. 4. 220V network indicator circuit with two LEDs.
Rice. 5. Diagram of a 220V network indicator with two LEDs and a capacitor.
But, if you only need one LED, the second one can be replaced with a regular diode, for example, 1N4148 (Fig. 6 and 7). And there is nothing wrong with the fact that this LED is not designed for mains voltage. Because the reverse voltage across it will not exceed the forward voltage of the LED.
Rice. 6. 220V network indicator circuit with LED and diode.
Rice. 2. Diagram of a 220V network indicator with one LED and a capacitor.
In the circuits, two-color LEDs of the L-53SRGW type and single-color LEDs of the AL307 type were tested. Of course, you can use any other similar indicator LEDs. Resistors and capacitors can also be of other sizes - it all depends on how much current needs to be passed through the LED.
Andronov V. RK-2017-02.
