Universal watch-timer. Scheme, description

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ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
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Universal watch-timer. Encyclopedia of radio electronics and electrical engineering

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Encyclopedia of radio electronics and electrical engineering / Clocks, timers, relays, load switches

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In everyday practice, there is a need to count and display the current time, time intervals, turn on and off various loads at a certain time. These functions can be implemented using a universal electronic clock with autonomous power supply, automatic brightness control of the indicator, signal (musical) and actuating devices.

The schematic diagram is shown in Fig.1.

Fig.1 (click to enlarge)

The radio designer "Start-2039" was taken as the basis for the author's development of the watch, the possibilities of which were expanded. The watch implements the following functions: emits a melodious signal when the current time coincides with the time previously set in the B1 and B2 alarm clocks; turn on the load when the current time coincides with the pre-set alarm time B1 and turn off the load when it coincides with the alarm B2; automatically adjust the brightness of the indicator glow depending on the illumination in the room; have both mains power and an autonomous power source from a battery of cells through a voltage converter, while allowing the numbers to be displayed on the indicator when the KN button is pressed briefly.

The watch is assembled on a KR145IK1901 chip, which is designed to control devices in real time: a programmable alarm clock and a timer. The microcircuit has a master oscillator with an excitation frequency of 32768 Hz. This frequency is determined by the resonator BQ1 and capacitors C1, C2, C5: the latter serves to fine-tune the frequency of the generator.

At the outputs of the microcircuit 1-7 (pins 13-20), a code is generated to indicate the numbers on the indicator type IVL2-7/5 with dynamic control, i.e. only one digit is displayed at a time.

To implement the dynamic mode, the outputs of the microcircuit D1 - D4 (pins 44 - 47) are used, which, together with the inputs K1 - K4 (pins 39 - 42), serve to control the operating modes of the clock. From the outputs Y5 and Y6 (pins 27, 28) through the diodes VD1 HVD2 to the base of the transistor VT3 signals of two alarm clocks are received. The base of transistor VT3 is connected to the collector of transistor VT4. In the initial state (in the absence of alarm signals), the transistor VT3 is open and no signals are received at the base of the transistor VT4.

If there is an alarm signal at outputs 27 or 28, the transistor VT3 closes, and the transistor VT4 opens, and thus the level + Upit is set at pin 13 (ZP) of the DD2 chip. and a melodic signal is formed at the output of the microcircuit.

The flashing of the service marks of the HL1 indicator in a second discharge is carried out by applying a signal with a frequency of 1 Hz from the output Y4 (pin 26) to the anodes "k" and "e" of the indicator.

-27 V power is supplied to pins 1 and 48 of the microcircuit, +27 V to pin 24.

Purpose of the clock control buttons:

K1 - "B" - call indication of the current time;
K2 - "H" - setting the current time in hours; in the "Timer" mode - in minutes;
KZ - "M" - setting the current time in minutes; in "Timer" mode - in seconds;
K4 - "K" - correction of the current time;
K5 - "T" - switching on the "Timer" mode;
KB - "C" - turn on the current time in minutes and seconds;
K7 - "0" - stop (fixation) of the indicator readings;
K8 - "B1" - "alarm clock 1" mode - setting the time is done with the buttons K2 and KZ ("H" and "M");
K9 - "B2" - "alarm clock 2" mode - setting the on time is done using the "H" and "M" buttons;
K10 - "P" - choice of melodies;
K11 - "P" - switching on the indication when the clock is powered from an independent power source;
K12 - "On." - turning on the executive device in manual mode;
K13 - "Off" - turning off the actuator (device).

The signal musical device is assembled on the UMS-7(8) DA2 chip. The principle of operation of the device is as follows.

When the input 13 of the microcircuit receives a signal from one of the clock alarm clocks through a matching device on diodes VD1, VD2 and transistors VT3, VT4, the alarm device is turned on.

The choice of melodies is carried out by pressing the "P" button in the sequence: melody 1, melody 2, melody 3, etc. along the ring. The program is selected according to the level of the control action at the program selection input (output 6MS). In the initial position, the level at the input "BQ" is equal to +Upit - the first program. At the level at the input "BQ" -Upit - the second program.

Clock signals with a frequency of 32768 Hz from pin 3 of the KR145IK1901 chip through a divider on resistors R12 and R13 are fed to the BQ input (pin 8 of the DD2 chip).

The load of the UMS-7 (8) microcircuit is the ZP-3 piezoceramic bell connected to pins 1 and 14 (cl. A and B) of the microcircuit. When connected as a speaker speaker 0,5 GD 1 (2), the latter must be connected to pins 1 and 5 through an amplifier based on composite transistors VT6 and VT7.

The actuator is described in detail in [3].

Buttons K12 and K13 are used for manual control of the load. The following parts are used in the actuator: transistors VT1 and VT2 - KT3102A, VT5 - KT814, KT816 with any letter, relay K1 - RES-60 (passport RS4.569.435-00 / -05).

The power source is described in the article by G. Krupetsky "Once again about the alarm clock from the Start 7176 set" (see "Radio", N12, 1987, p. 30-31). Its design allows autonomous power supply - from a battery 4,5 V (4 elements 332) and from the mains through a voltage converter on transistors VT9 -VT11.When powered from the mains, the current time is displayed on the HL1 indicator constantly, in offline mode - with a short press of the K11 button.

The power supply has a unit for automatically controlling the brightness of the indicator glow, made on a VT8 transistor, a photoresistor R16 of the SFZ-1 type and resistors R15 and R18. The first resistor sets the illumination level of the indicator at low lighting in the room, the second - at normal illumination.

The network transformer was used from the "Start -2039" set, only the number of winding turns was changed. The W4 winding is wound up for a voltage of 2,4 V for the glow of the IVL-2-7 / 5 indicator with an average output. The winding contains 48 turns of wire PEV-2 0,1 - 0,09. Winding is carried out in one layer (from bottom to top) with two wires - 24 turns. After assembly, the transformer can be tested in idle mode. The terminals must have voltages U1-24-40 V, U2-6B, U3-2x19B.

The pulse transformer is wound on a K16x8, 5x5 mm ring magnetic core made of M1500NM1 grade ferrite. W1-36 turns, W2-6 turns with PEV-2 wire 0,31, W3-12 turns with PEV-2 wire 0,31.

The actuator is powered from a compensation stabilizer on a VT5 transistor, and the UMS-7 (8) microcircuit of a musical synthesizer is powered from a parametric stabilizer on VD5 of the KS1ZZA type and resistor R17.

A drawing of the circuit board is shown in Fig.2.

Universal watch-timer
Ris.2

References:

G. Krupetskikh. "Once again about the alarm clock from the set "Start 7176", "Radio" 1987 N11, p.30-31.
"Radio-electronic set "Start-2039" (electronic alarm clock, block). Operation manual.
Improvement of electronic clock. "Radio" 1990 N11.c.33

Author: G.Repin

See other articles Section Clocks, timers, relays, load switches.

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