Decatron

The simplest design is a double-pulse reversible decatron. Around a single disk anode there are ten isolated pins - indicator cathodes . Between each pair of adjacent indicator cathodes are two so-called. subcathode - first and second; all first and all second sub-cathodes are combined by two sub-cathode buses. The output voltage is removed from the resistors connected between the cathodes and ground. Thus, the 10-bit counter-switch has 13 pins (anode, 10 cathodes and 2 subcathodes); There are also decatron dividers in which only one out of ten cathodes has an external output.

At rest, a relatively small positive bias is applied to the sub cathodes relative to the indicator cathodes (30–40 Volts ). When a constant positive voltage is applied to the anode sufficient to cause a glow discharge (130–150 V for slow decatrons filled with a mixture of inert gases , or 420–450 V for fast decatrons filled with hydrogen ), a discharge occurs between the anode and one of the indicator cathodes. The discharge cannot pass to either subcathodes (due to a positive bias) or to neighboring indicator cathodes (subcathodes form an effective barrier, and the anode resistance limits the discharge current). In order for the counting to begin precisely from the zero cathode, and not from an arbitrarily lit one, a reset pulse of 100-150 V voltage is applied to the zero cathode.

To move a discharge to an adjacent cathode, a short negative pulse must first be applied to the first subcathode. The pulse amplitude must be sufficient so that the potential of the subcathode drops below the potential of the cathodes. As soon as the bias at the sub-cathode becomes negative, the discharge moves from the cathode to the sub-cathode. The next negative pulse is supplied to the second subcathode with a slight overlap relative to the first, as a result, the discharge jumps to the second subcathode. When the second pulse is removed, the potential of the second subcathode increases, and the discharge jumps to the nearest indicator cathode. Although all cathodes are under the same voltage relative to the common subcathode, only the cathode that is closest to the ionized zone lights up.

After ten pairs of control pulses, the discharge describes a full circle. If the design of the sub-cathodes is symmetrical, then the lamp can shift the discharge between the cathodes both clockwise and against it - for this it is enough to apply the first pulse to the second sub-cathode, and the second pulse to the first sub-cathode.

Soviet decatrons are represented by various models that differ in size, type of cap, device, maximum counting frequency, operating hours and other parameters, type of gas filling, and, accordingly, the color of the glow.

Decatrons A101, A102, OG4, OG9, A201 have an orange - red color .

The blue color of the glow has a decatron A107.

Decatrons A109, A110, OG7, OG8 have a blue glow.

Violet - blue color of glow have decatrons A103, A108.

OG3 decatrons have a violet glow color .

• The counting speed is limited to 10..100 kHz for fast decatrons with hydrogen filling and units of kHz for decatrons filled with inert gases. At the same time, hydrogen decatrons are less reliable and stable;
• With long-term discharge retention at one of the cathodes, the emission properties of the other cathodes deteriorate, and the decatron “ages”, however, this aging is reversible to a certain limit. Decatrons are restored at a quick count, so the designers of multi-digit counters recommended a periodic change of instruments in different discharges;
• The anode current of the decatrons is limited to values ​​in tenths and units of milliamps, while it is recommended to select the working current of the anodes at ~ 1/2 of the maximum allowable current to increase the service life;
• During operation, the switching sequence must be strictly observed - first the bias, then the anode voltage, and last but not least, the reset pulse;
• Decatrons require a voltage of about 400 V for their power supply, so careful observance of electrical safety measures is necessary when setting up and repairing devices containing these devices.
• When building multi-digit counters, decatrons cannot be directly connected to each other. A matching interstage amplifier made on a lamp , thyratron or transistor is required .

Due to the scarcity of decatrons, it is not so often that more than one device of the same type gets to fans. Since this is not enough for the manufacture of watches, the most common amateur radio design on a decatron is the so-called "decatron rotator", many of which are found by search engines on request "dekatron spinner". This is a decorative device in which the decatron is forced to count periods of alternating voltage in the network. Since all structural elements are galvanically connected to the network, the voltage of which, moreover, is doubled in the circuit , safety measures must be strictly observed during its assembly and operation.

• Decimal number system

• B.V. Katsnelson, A.M. Kalugin, A.S. Larionov. Vacuum electronic and gas-discharge devices. - M .: Radio and communications, 1985 .-- S. 491-505.
• V.S. Zgursky, B.L. Lisitsyn. Indication elements. - M.: Energy, 1980 .-- 304 p., Ill.