Radio circuits and electrical circuit diagrams. Rectangular pulse generator on K561LA7 K561LA7 application of time relay circuit
Based on the K561LA7 microcircuit, you can assemble a generator that can be used in practice to generate pulses for any systems, or the pulses, after amplification through transistors or thyristors, can control lighting devices (LEDs, lamps). As a result, it is possible to assemble a garland or running lights on this chip. Further in the article you will find a circuit diagram for connecting the K561LA7 microcircuit, a printed circuit board with the location of radio elements on it, and a description of how the assembly works.
The principle of operation of the garland on the KA561 LA7 microcircuit
The microcircuit begins to generate pulses in the first of 4 elements 2I-NOT. The duration of the LED glow pulse depends on the value of capacitor C1 for the first element and, respectively, C2 and C3 for the second and third. Transistors are actually controlled “keys”; when control voltage is applied from the elements of the microcircuit to the base, when they open, they allow electricity from the power source and feed the chains of LEDs.
Power is supplied from a 9 V power supply, with a rated current of at least 100 mA. If installed correctly, the electrical circuit does not require adjustment and is immediately operational.
Designation of radio elements in the garland and their ratings according to the above diagram
R1, R2, R3 3 mOhm - 3 pcs.;
R4, R5, R6 75-82 Ohm - 3 pcs.;
C1, C2, C3 0.1 uF - 3 pcs.;
HL1-HL9 LED AL307 - 9 pcs.;
D1 microcircuit K561LA7 - 1 pc.;
The board shows the etching paths, the dimensions of the textolite and the location of radio elements during soldering. For etching the board, it is possible to use a board with one-sided copper coating. In this case, all 9 LEDs are installed on the board; if the LEDs are assembled in a chain - a garland, and not mounted on the board, then its dimensions can be reduced.
Technical characteristics of the K561LA7 chip:
Supply voltage 3-15 V;
- 4 logical elements 2I-NOT.
Figure 2 shows a diagram of a simple time relay with LED indication. Time counting begins at the moment the power is turned on by switch S1. At the very beginning, capacitor C1 is discharged and the voltage on it is low (like a logical zero). Therefore, the output D1.1 will be one, and the output D1.2 will be zero. LED HL2 will be lit, but LED HL1 will not be lit. This will continue until C1 is charged through resistors R3 and R5 to a voltage that element D1.1 understands as a logical one. At this moment, a zero appears at the output of D1.1, and a one appears at the output of D1.2.
Button S2 is used to restart the time relay (when you press it, it closes C1 and discharges it, and when you release it, charging C1 starts again). Thus, the countdown begins from the moment the power is turned on or from the moment the S2 button is pressed and released. LED HL2 indicates that the countdown is in progress, and LED HL1 indicates that the countdown has completed. And the time itself can be set using variable resistor R3.
You can put a handle with a pointer and a scale on the shaft of resistor R3, on which you can sign the time values, measuring them with a stopwatch. With the resistances of resistors R3 and R4 and capacitance C1 as in the diagram, you can set shutter speeds from several seconds to a minute and a little longer.
The circuit in Figure 2 uses only two IC elements, but it contains two more. Using them, you can make it so that the time relay will sound a sound signal at the end of the delay.
Figure 3 shows a diagram of a time relay with sound. A multivibrator is made on elements D1 3 and D1.4, which generates pulses with a frequency of about 1000 Hz. This frequency depends on resistance R5 and capacitor C2. A piezoelectric “tweeter” is connected between the input and output of element D1.4, for example, from electronic watch or handset, multimeter. When the multivibrator is working it beeps.
You can control the multivibrator by changing the logic level at pin 12 of D1.4. When there is zero here, the multivibrator does not work, and the “beeper” B1 is silent. When one. - B1 beeps. This pin (12) is connected to the output of element D1.2. Therefore, the “beeper” beeps when HL2 goes out, that is, the sound alarm turns on immediately after the time relay has completed its time interval.
If you don’t have a piezoelectric “tweeter”, instead of it you can take, for example, a microspeaker from an old receiver or headphones or telephone. But it must be connected through a transistor amplifier (Fig. 4), otherwise the microcircuit can be damaged.
However, if we don’t need LED indication, we can again get by with only two elements. Figure 5 shows a diagram of a time relay that only has an audible alarm. While capacitor C1 is discharged, the multivibrator is blocked by logical zero and the beeper is silent. And as soon as C1 is charged to the voltage of a logical unit, the multivibrator will start working, and B1 will beep. In Figure 6, the circuit sound alarm, feeding intermittently sound signals. Moreover, the sound tone and interruption frequency can be adjusted. It can be used, for example, as a small siren or apartment bell.
A multivibrator is made on elements D1 3 and D1.4. generating audio frequency pulses, which are sent through an amplifier on transistor VT5 to speaker B1. The tone of the sound depends on the frequency of these pulses, and their frequency can be adjusted by variable resistor R4.
To interrupt the sound, a second multivibrator is used on elements D1.1 and D1.2. It produces pulses of significantly lower frequency. These pulses arrive at pin 12 D1 3. When the logical zero here, the multivibrator D1.3-D1.4 is turned off, the speaker is silent, and when it is one, a sound is heard. This produces an intermittent sound, the tone of which can be adjusted by resistor R4, and the interruption frequency by R2. The sound volume largely depends on the speaker. And the speaker can be almost anything (for example, a speaker from a radio, telephone, radio receiver, or even acoustic system from the music center).
Based on this siren, you can make a security alarm that will turn on every time someone opens the door to your room (Fig. 7).
A device for creating the effect of lights running from the center to the edges of the sun. Number of LEDs - 18 pcs. Upit.= 3...12V.
To adjust the flicker frequency, change the values of resistors R1, R2, R3 or capacitors C1, C2, C3. For example, doubling R1, R2, R3 (20k) will reduce the frequency by half. When replacing capacitors C1, C2, C3, increase the capacitance (22 µF). It is possible to replace K561LA7 with K561LE5 or with a complete foreign analogue of CD4011. The values of resistors R7, R8, R9 depend on the supply voltage and the LEDs used. With a resistance of 51 Ohms and a supply voltage of 9V, the current through the LEDs will be slightly less than 20mA. If you need the efficiency of the device and you use bright LEDs at low current, then the resistance of the resistors can be significantly increased (up to 200 Ohms and even more).
Even better, when using a 9V power supply, use serial connection LEDs:
Below are drawings of printed circuit boards of two options: the sun and the mill:
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A schematic diagram of a simple homemade photo relay on a K561 series microcircuit is given. The photo relay is designed to turn on the lighting at nightfall and turn it off at dawn. The phototransistor FT1 serves as a natural light level sensor.
Current is supplied to the lamp through a switching stage using high-voltage field-effect switching transistors, which operate similarly to a mechanical switch. Therefore, the lamp can be based either on an incandescent lamp or on the basis of any energy saving lamp(LED, fluorescent). The only limitation is that the lamp power should not be more than 200W.
Photo relay circuit
In the initial state, when it is dark, capacitor C1 is charged. The output of element D1.3 is one. It opens field-effect transistors VT2 and VTZ, and through them an alternating voltage of 220V is supplied to the lamp H1. Resistor R5 limits the charging current of the gate capacitance of field-effect transistors.
Rice. 1. Schematic diagram homemade photo relay on the K561LA7 microcircuit.
When light, the emitter-collector resistance of phototransistor FT1 decreases (it opens). The voltage at the D1.1 inputs connected together is equal to logical zero. The output D1.1 is one.
Transistor VT1 opens and discharges capacitor C1 through resistor R3, which limits the discharge current of C1. The voltage at the D1.2 inputs connected together drops to logical zero. A logical zero appears at output D1.2. Transistors VTZ and VT2 are closed, so no voltage is supplied to the lamp.
After the next decrease in illumination, the emitter-collector resistance FT1 increases (the phototransistor closes). Through R1, a logic one voltage is supplied to the inputs of element D1.1 connected together. The output D1.1 is zero, so transistor VT1 closes.
Now capacitor C1 begins to slowly charge through R4. After some time (1.5-2 minutes), the voltage on it reaches logical unity. At output D1.3, the voltage increases to logical one. Transistors VT2 and VTZ open and the lamp turns on.
Due to the time delay caused by charging capacitor C1 through R4, the circuit does not respond to a sharp and short-term increase in illumination, which can occur, for example, from the influence of the headlights of a car passing in the visibility zone of FT1.
The logic circuit is powered by a source based on diode VD4 and parametric stabilizer VD1-R6. Capacitor C2 smoothes out ripples. The most dangerous element in the circuit is resistor R6.
It drops significant voltage and power. When installing, it is advisable not to cut off its leads, but to bend and install the resistor so that its body is above the board and above the entire installation. That is, so that there are no conditions for breakdown to other parts through dust or humidity.
Parts and PCB
When the power consumption of the lamp is no more than 200W, transistors VT2 and VTZ do not need any radiators. You can also work with a lamp with a power of up to 2000W, but with appropriate radiators for these transistors.
The circuit is assembled on a miniature printed circuit board shown in the figure.
Rice. 2. Printed circuit board for a homemade photo relay circuit.
Instead of the L-51P3C phototransistor, you can use another phototransistor, as well as a photoresistor or photodiode in reverse connection (anode instead of emitter, cathode instead of collector).
In any case, the resistance R1 must be selected so that the circuit operates reliably (in the case of a photodiode, the resistance R1 will have to be significantly increased, and with a photoresistor, its resistance will depend on the nominal resistance of the photoresistor).
- Microcircuit D1 - K561LE5 or K561LA7, as well as K176LE5, K176LA7 or imported analogs such as CD4001, CD4011.
- Transistor KT3102 - any similar one.
- IRF840 transistors can be replaced with BUZ90 or other analogues, as well as with domestic KP707B - G.
- The KS212Zh zener diode can be replaced with any 10-12V zener diode.
- Diodes 1N4148 can be replaced with any KD522, KD521. Rectifier diode
- 1N4004 can be replaced with 1N4007 or KD209.
- All capacitors must have a voltage of at least 12V.
Setting up
The entire setup of the photo relay circuit comes down to setting up the photosensor by selecting resistance R1. If you want or need to change the setting quickly, this resistor can be replaced with a variable one.
The spatial installation of the photo relay and lamp plays an important role. It is necessary to ensure that the photo relay, namely the photo transistor, is located out of direct light from the lamp. For example, if the lamp is located under an opaque canopy, then FT 1 should be somewhere above this canopy.
