Counting signaling device. Scheme, description

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Counting signaling device. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Security devices and object signaling

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The signaling counting device (hereinafter simply USS) controls the opening of the front door and counts the number of openings of the front door from the moment the device is powered on. Opening the entrance door leads to the closing of the contacts of the reed switch "Door" and the start of the timer, which turns on the light and sound signaling device "Guests".

The "Guests" beacon is a buzzer tone interrupted by two red MSDs (flashing LEDs). Due to the small difference in the frequencies of the clock generators built into the MSD, the tone interruption is not periodic, and therefore becomes more noticeable, especially in conditions of increased noise in the room with various sounds. The timer runs for 7 seconds.

Additionally, the USS is equipped with a button "№", which allows you to manually at any time see the number of past events (opening the front door).

The USS circuit (see Fig. 1) consists of the following main parts: the circuit for setting to "0" when the power is turned on on the elements C1, R1; sensor - reed switch SF1 "Door" and resistor R2, which introduces (in the initial position) the transistor VT1 into the cut-off mode; amplifier "bounce" on the elements VT1, R3; timer on the chip (elements DD1.1, R4, C2, VD2, VD3); trigger "overflow" on the chip DD1.2; decoupling circuits on diodes VD1, VD2 (logic element "2OR" on discrete elements); counter - decoder DD2, working on a seven-segment LED indicator HG1 red glow; current key on a field-effect transistor VT2; light and sound signaling device "Guests" on elements A1...AZ, C4; power source - GB1 batteries.

Rice. 1 (click to enlarge)

When the power is turned on, the SA1 toggle switch starts charging the capacitor C1. The current flows through the circuit: "+" GB1, C1, R1, common wire. While the capacitor C1 is not charged, on its lining "-" there is a logic level 1, which sets the counter DD2 to its initial (zero) state (at the input "R" - output 5). The same installation pulse is applied to the input R (pin 10) of the IC DD1.2 and - through the diode VD1 - to the input R (pin 4) of the IC DD1.1. So the USS is set to its initial state (standby mode). Closing the contacts of the reed switch SF1 "Door" leads to the supply of a positive voltage drop (with a "bounce") to the source follower - the amplifier of the "steepness" of the fronts VT1, R3 and further, from the source VT1 - to the input C (pin 3) of the trigger DD1.1. Since the supply voltage (logic 5) is applied to the input D (pin 1.1) DD1, a logical 1 is set at the non-inverting output Q (pin 1.1) of the IC DD1. The current key on the transistor VT2 also opens through its complex drain load A1 ... AZ, C4 (light and sound signaling device "Guests") current flows for 7 seconds. The duration of the cycle is determined by the timing circuit R4, C2.

The timer works on the IC DD1.1 as follows. Set at the output (pin 1) DD1.1 logical 1 through the resistor R4 charges the capacitor C2. When the voltage on the "+" plate C2 rises to half the supply voltage (plus a direct voltage drop across the diode VD2 of the order of +0,7 V), the trigger DD1.1 (at the input R - pin 4) is reset and a logical 0 is set at the output Q. Capacitor C2 is quickly discharged through the VD3 diode, the drain load VT2 is turned off. At the end of the timer, the field-effect transistor VT2 entered the cut-off mode and, as a result, the battery capacity saving mode GB1.

Immediately after the operation of SF1 "Door" (and the start of the timer) from the output (pin 2) of the IC DD1.1, a negative voltage drop is applied to the counting input C (pin 4) of DD2 and increases the contents of the counter DD2 by one. A similar increase in the contents of the counter DD2 occurs after each opening of the door, and the passage of a counting negative difference. The DD2 microcircuit has an "overflow" output (pin 2), on which a logical 5 is present from the beginning of the 9th to the end of the 1th counting pulse. Therefore, at the end of the first counting cycle (0 ... 9), a negative voltage drop from the output 2 DD2 through the resistor R6 enters the base of the bipolar transistor VT3 and closes it.

Transistor VT3 operates in key mode and inverts the input signal. Thus, a positive voltage drop is formed on the VT3 collector, which is fed to input C (pin 11) of the "overflow" trigger DD1.2. In this case, the logical 1 from the information input D (pin 9) DD1.2 is recorded on the non-inverting output Q (pin 13) DD1.2.

A high logic level from output Q DD1.2 goes to pin 10 (segment "h", "comma") of the seven-segment indicator HG1 and prepares it for ignition (when the SB1 "No." button is pressed). As can be seen from the diagram, both the number and the comma (segment "h") on the HG1 indicator can only light when the "No" button is pressed (in manual mode). The rest of the time the OSS is in power-saving mode. If when you press the SB1 "No." button, a comma is brightly lit along with the number, then the OSS has switched to overflow mode, that is, more than 9 events (door openings) have occurred, and it is recommended to reset the counter by turning the OSS off and on again with the SA1 "Power" toggle switch. In principle, you can do without zeroing, but when reading the readings, it will not be clear how many (10, 20, 30 or more) events will need to be added to the indicator readings in order to get the actual number of door openings.

When the door is closed, the reed switch SF1, returning to its original state, does not bounce the contacts, and by the negative voltage drop at the input C (pin 3) DD1.1 restart the timer assembled on the elements DD1.1, R4, C2, VD2, VD3, not happening. Light and sound signaling device "Guests" works as follows. When the transistor VT2 opens for the duration of the timer, a positive-polarity DC voltage from the battery GB1 passes through the buzzer (block A1) to two MSDs connected in parallel (blocks A2 and A3).

Since the resistance of the open channel VT2 is a few ohms, the operating current of the buzzer is mainly determined by its own resistance of the buzzer (block A1) and the operating currents of the MSD. The MSDs start flashing brightly and manipulate (control) the periodic buzzer sounds. The sound of the buzzer occurs continuously due to the storage capacitor C4, but has a pulsating character, determined by the operating modes of the MSD. (Strictly speaking, two MSDs are used to increase the operating current of the buzzer to 20 mA, and the use of different types of MSDs with slightly different flash rates gives greater shrillness.)

Setting

Assembled without errors, the OSS usually does not require tuning. The operating time of the timer can be specified by selecting the resistor R4*. The brightness of the glow of the seven-segment indicator HG1 (when the SB1 "No." button is pressed) depends on the value of the resistor R5. The brightness of the HG1 indicator can be slightly increased by excluding (shorting) the resistor R5. However, in this case, it will be necessary to limit the current (by the same resistor) in the power supply circuit of the "h" segment. This is explained by the fact that the output current of logical 1 output 13 DD1.2 is much greater than the output current (short circuit current) of the logical unit of the outputs of the microcircuit

DD2. The USS remains operational when the supply voltage drops to +5 V. The lower limit of operability is mainly determined by the load: sequential activation of the buzzer A1 (+3 V) and MSD A1 and A2 (minimum +2 V). The length of the wire line connecting the SF1 reed switch with the OSS housing, in the author's version, was 2,2 meters. If false positives of the USS appear, which are possible with a longer line length, the resistor R2 should be shunted with an additional ceramic capacitor with a capacitance of about 0,022 μF.

Details

In the USS, resistors of the OMLT type are used. Capacitors C1, C2, C4 - oxide type K50-35 or foreign production. C3 - ceramic, type KM5, K10-7, K10-17. Diodes - any silicon, for example KD520 ... KD522. Field effect transistor VT1 can be replaced by BS170; VT2 - type KP501 with any letter index. Transistor VT3 - any silicon low-power type KT301, KT306, KT312, KT315, KT342 (different pinouts) with a current gain of at least 100. Button SB1 KM1-I or other small; toggle switch SA1 - small-sized MTS-102 or extra small-sized SMTS-102. Socket XS1 type SNTs-3,5 with nut fastening. The USS uses a DD1 chip of the K561 series, which can be replaced by a foreign analogue CD4013A. DD2 K176IE4 has no foreign analogues. The HG1 indicator can be replaced with a similar one with combined cathodes (another pinout will require the revision of the software and, possibly, the inclusion of a current-limiting resistor in the circuit of each segment, if the indicator is not super bright, to equalize the brightness of the glow of the segments). Reed switch SF1 - any type of "tee", having at least normally closed contacts.

The standby current of the USS is determined mainly by the state of the inverter VT3, R7: through the open transistor VT3, the current reaches 23 μA. The microcircuit consumes a current of no more than 1 μA. Therefore, if the transistor VT3 is replaced by an inverter (1/4 of the IC K561LA7 or K561LE5), then the USS will turn out to be a very economical device, but this will require an increase in the size of the printed circuit board. You can also try instead of the bipolar transistor VT3 (KT3102) to install a field-effect transistor of the KP501 type, increasing the resistance R7 tenfold, and install a jumper instead of the resistor R5. The conclusions B, K, E of the bipolar transistor must correspond to the conclusions 3, C, and the field-effect transistor (respectively). In this case, the estimated standby current of the USS will be 2,5 μA, which is comparable to the battery self-discharge current.

The GB1 uses a foreign-made 6F22 - 9V type alkaline miniature battery. Domestic analogue - "Korund" is better not to use. If the 9-12-month service life of such a battery (with continuous operation in standby mode) is not enough, then (with an increase in the size of the case) 2 "flat" batteries 3R12 (+4,5 V) are used, connected in series.

Author: A. Oznobikhin, Irkutsk

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