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 “switches”; when control voltage is supplied from the elements of the microcircuit to the base, when they open, they pass electric current from the power source and power 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 chip 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.

The K561LA7 microcircuit (or its analogs K1561LA7, K176LA7, CD4011) contains four 2I-NOT logic elements (Figure 1). The operating logic of the 2I-NOT element is simple - if both of its inputs are logical ones, then the output will be zero, and if this is not the case (that is, there is a zero at one of the inputs or both inputs), then the output will be one. The K561LA7 chip is CMOS logic, which means that its elements are made using field-effect transistors, so the input resistance of the K561LA7 is very high, and the energy consumption from the power supply is very low (this also applies to all other chips of the K561, K176, K1561 or CD40 series).

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 more.

The circuit in Figure 2 uses only two IC elements, but it contains two more. Using them, you can make the time relay 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 an electronic watch or a handset, or a multimeter. When the multivibrator is working it beeps.

You can control the multivibrator by changing the logical 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. Figure 6 is a diagram of a sound alarm that produces intermittent 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. Thus, an intermittent sound is obtained, 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 point, or even a speaker system from a 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).

Logic chip. Consists of four logical elements 2I-NOT. Each of these elements includes four field-effect transistors, two n-channel - VT1 and VT2, two p-channel - VT3 and VT4. Two inputs A and B can have four combinations of input signals. Schematic diagram and truth table of one element of the microcircuit shown below.

Logic of operation of K561LA7

Let's consider the logic of operation of a microcircuit element . If a high level voltage is applied to both inputs of the element, then transistors VT1 and VT2 will be in the open state, and VT3 and VT4 will be in the closed state. Thus, the Q output will be low. If a low level voltage is applied to any of the inputs, then one of the transistors VT1, VT2 will be closed, and one of VT3, VT4 will be open. This will set a high level voltage at output Q. The same result, naturally, will occur if a low level voltage is applied to both inputs of the K561LA7 microcircuit. The motto of the AND-NOT logical element is that zero at any input gives one at the output.

Entrance		Output Q
A	B
H	H	B
H	B	B
B	H	B
B	B	H

Truth table of the K561LA7 microcircuit

Pinout of the K561LA7 chip

Scheme of a simple and affordable metal detector based on the K561LA7 chip, also known as CD4011BE. Even a novice radio amateur can assemble this metal detector with his own hands, but despite the spaciousness of the circuit, it has quite good characteristics. The metal detector is powered by a regular crown, the charge of which will last for a long time, since the power consumption is not large.

The metal detector is assembled on just one K561LA7 (CD4011BE) chip, which is quite common and affordable. To configure, you need an oscilloscope or a frequency meter, but if you assemble the circuit correctly, then these devices will not be needed at all.

Metal detector circuit

Metal detector sensitivity

As for the sensitivity, but it is not bad enough for such a simple device, say, it sees a metal can from a can at a distance of up to 20 cm. A coin with a face value of 5 rubles, up to 8 cm. When a metal object is detected, a tone will be heard in the headphones, the closer the coil is to object, the stronger the tone. If the object has a large area, say, like a sewer hatch or a pan, then the detection depth increases.

Metal detector components

• You can use any low-frequency, low-power transistors, such as those on KT315, KT312, KT3102 or their foreign analogues VS546, VS945, 2SC639, 2SC1815
• The microcircuit is K561LA7, it can be replaced with an analog CD4011BE or K561LE5
• Low-power diodes such as kd522B, kd105, kd106 or analogues: in4148, in4001 and the like.
• Capacitors 1000 pF, 22 nF and 300 pF should be ceramic, or better yet, mica ones, if available.
• Variable resistor 20 kOhm, you need to take it with the switch or the switch separately.
• Copper wire for the coil, suitable for PEL or PEV with a diameter of 0.5-0.7 mm
• Headphones are ordinary, low-impedance.
• The battery is 9 volts, the crown is quite suitable.

Some information:

The metal detector board can be placed in a plastic case from automatic machines, you can read how to make it in this article:. In this case, a junction box was used))

If you do not confuse the part values, if you solder the circuit correctly and follow the instructions to wind the coil, then the metal detector will work immediately without any special settings.

If, when you turn on the metal detector for the first time, you do not hear a squeak in the headphones or a change in frequency when adjusting the “FREQUENCY” regulator, then you need to select a 10 kOhm resistor in series with the regulator and/or a capacitor in this generator (300 pF). Thus, we make the frequencies of the reference and search generators the same.

When the generator is excited, whistling, hissing or distortion appears, solder a 1000 pF (1nf) capacitor from the sixth pin of the microcircuit to the case, as shown in the diagram.

Using an oscilloscope or frequency meter, look at the signal frequencies at pins 5 and 6 of the K561LA7 microcircuit. Achieve their equality using the above-described adjustment method. The operating frequency of generators can range from 80 to 200 kHz.

A protective diode (any low-power one) is needed to protect the microcircuit if, for example, you connect the battery incorrectly, and this happens quite often.))

Metal detector coil

The coil is wound with PEL or PEV wire 0.5-0.7 mm on a frame, the diameter of which can be from 15 to 25 cm and contains 100 turns. The smaller the coil diameter, the lower the sensitivity, but the greater the selectivity of small objects. If you are going to use a metal detector to search for ferrous metal, it is better to make a larger diameter coil.

The coil can contain from 80 to 120 turns, after winding it is necessary to wrap it tightly with electrical tape as shown in the diagram below.

Now you need to wrap some thin foil around the top of the electrical tape, food grade or chocolate foil will do. You don’t need to wrap it all the way, but leave a couple of centimeters, as shown below. Please note that the foil is wound carefully; it is better to cut even strips 2 centimeters wide and wrap the coil like electrical tape.

Now wrap the coil tightly with electrical tape again.

The coil is ready, now you can attach it to a dielectric frame, make a rod and assemble everything into a heap. The rod can be soldered from polypropylene pipes and fittings with a diameter of 20 mm.

To connect the coil to the circuit, a double shielded wire (screen to the body) is suitable, for example the one that connects a TV to a DVD player (audio-video).

How a metal detector should work

When turned on, use the “frequency” control to set a low-frequency hum in the headphones; when approaching metal, the frequency changes.

The second option, so that there is no buzzing in the ears, is to set the beats to zero, i.e. combine two frequencies. Then there will be silence in the headphones, but as soon as we bring the coil to the metal, the frequency of the search generator changes and a squeak appears in the headphones. The closer to the metal, the higher the frequency in the headphones. But the sensitivity with this method is not great. The device will react only when the generators are strongly detuned, for example, when brought close to a jar lid.

Location of DIP parts on the board.

Location of SMD parts on the board.

Metal detector board assembly

Let's look at the circuits of four electronic devices built on the K561LA7 (K176LA7) microcircuit. The schematic diagram of the first device is shown in Figure 1. This is a flashing light. The microcircuit generates pulses that arrive at the base of transistor VT1 and at those moments when a voltage of a single logical level is supplied to its base (through resistor R2), it opens and turns on the incandescent lamp, and at those moments when the voltage at pin 11 of the microcircuit is equal to zero level the lamp goes out.

A graph illustrating the voltage at pin 11 of the microcircuit is shown in Figure 1A.

Fig.1A
The microcircuit contains four logical elements "2AND-NOT", the inputs of which are connected together. The result is four inverters (“NOT”. The first two D1.1 and D1.2 contain a multivibrator that produces pulses (at pin 4), the shape of which is shown in Figure 1A. The frequency of these pulses depends on the parameters of the circuit consisting of capacitor C1 and resistor R1. Approximately (without taking into account the parameters of the microcircuit), this frequency can be calculated using the formula F = 1/(CxR).

The operation of such a multivibrator can be explained as follows: when the output D1.1 is one, the output D1.2 is zero, this leads to the fact that capacitor C1 begins to charge through R1, and the input of element D1.1 monitors the voltage on C1. And as soon as this voltage reaches the level of logical one, the circuit seems to be turned over, now the output D1.1 will be zero, and the output D1.2 will be one.

Now the capacitor will begin to discharge through the resistor, and input D1.1 will monitor this process, and as soon as the voltage on it becomes equal to logical zero, the circuit will turn over again. As a result, the level at output D1.2 will be pulses, and at output D1.1 there will also be pulses, but in antiphase to the pulses at output D1.2 (Figure 1A).

A power amplifier is made on elements D1.3 and D1.4, which, in principle, can be dispensed with.

In this diagram, you can use parts of a wide variety of denominations; the limits within which the parameters of the parts must fit are marked on the diagram. For example, R1 can have a resistance from 470 kOhm to 910 kOhm, capacitor C1 can have a capacitance from 0.22 μF to 1.5 μF, resistor R2 - from 2 kOhm to 3 kOhm, and the ratings of parts on other circuits are signed in the same way.

Fig.1B
The incandescent lamp is from a flashlight, and the battery is either a 4.5V flat battery or a 9V Krona battery, but it is better if you take two “flat” ones connected in series. The pinout (pin location) of the KT815 transistor is shown in Figure 1B.

The second device is a time relay, a timer with an audible alarm for the end of the set time period (Figure 2). It is based on a multivibrator, the frequency of which is greatly increased compared to the previous design, due to a decrease in the capacitance of the capacitor. The multivibrator is made on elements D1.2 and D1.3. Resistor R2 is the same as R1 in the circuit in Figure 1, and the capacitor (in this case C2) has a significantly lower capacitance, in the range of 1500-3300 pF.

As a result, the pulses at the output of such a multivibrator (pin 4) have an audio frequency. These pulses are sent to an amplifier assembled on element D1.4 and to a piezoelectric sound emitter, which produces a high or medium tone sound when the multivibrator is operating. The sound emitter is a piezoceramic buzzer, for example from a handset telephone ringing. If it has three pins, you need to solder any two of them, and then experimentally select two of the three, when connected, the sound volume is maximum.

Fig.2

The multivibrator works only when there is a one at pin 2 of D1.2; if it is zero, the multivibrator does not generate. This happens because element D1.2 is a “2AND-NOT” element, which, as is known, differs in that if a zero is applied to its one input, then its output will be one, regardless of what happens at its second input .