Counters-decoders K561IE8. Converter based on powerful field-effect transistors and K561IE8 microcircuit K561IE8 switching circuit with reset

This microcircuit is convenient for implementing various circuits where it is necessary to alternately switch any loads. The above circuit ensures the sequential inclusion of nine pairs of LEDs; the use of more powerful switches will allow connecting incandescent lamps, LED strips, relay, etc.

Let's consider the principle of operation: a rectangular pulse generator with a frequency of 3-10 Hz is assembled on logic elements (2OR-NOT) DD1.1 and DD1.4, which is set by trimming resistor R2, or by selecting capacitor C1, the pulses are sent to the counting input of the DD2 microcircuit. When the device is turned on charging current capacitor C2 creates a positive pulse on resistor R3, which is converted into a logical one using elements DD1.2 and DD1.3, then it is fed to the counter reset input and counting always starts from pin 3 (otherwise, when power is applied, one is at the outputs can be set arbitrarily). As soon as the unit “reaches” pin 11 of the counter, through elements DD1.2 and DD 1.4 it will reset the counter to the beginning and the cycle will repeat. If desired, the number of channels can be reduced by moving the reset from pin 11 to the next one after the last channel.

This scheme worked in a car spoiler (before meeting with the traffic police), pairs of LEDs are located on opposite sides, so the lights on both sides converge to a point.

List of radioelements

The converter consumes no more than 7 mA in idle mode.
The K561IE8 counter-distributor has a reset input (pin 13), high level on which it returns the microcircuit to its original state. At this point, counting stops and all outputs except zero (pin 3) are reset to zero. Both output transistors VT1 and VT2 are closed, i.e. the converter is blocked.
The emergency blocking diagram is shown in. Capacitor C4 is charged through R13 to the supply voltage in the absence of pulses from output DD1.2 and supplies a logical “1” to the blocking input (pin 13 of DD2) through VD13. During normal operation of the converter, at the “Reset blocking” output (pin 1 of DD2), a logical “1” appears every 20 ms, which through R11 opens the transistor VT5 and discharges C4, thereby preventing the blocking from operating.
Battery overvoltage protection. When Ua>15 V is exceeded, the zener diode VD10 opens, VT4 opens with current through R9 and supplies a logical “1” through VD12 to the blocking input. This blocking is needed to prevent failure of power transistors. To protect the entire circuit in parallel with C5, you need to turn on the KS515 zener diode. This situation will not arise if Charger will not be connected to the inverter without a battery. It is better to connect the converter and charger to the battery with different wires.
Protection of DB from deep discharge. The value of R7 is selected in such a way that at Ua<10,5 В транзистор VT3 уже закрылся, светодиод VD9 погас, и через R8 и VD11 подалась логическая "1" на вход блокировки. С2 предотвращает блокировку в случае кратковременного понижения Ua.
Protection against incorrect switching on (reversal of polarity) of the battery. In case of emergency blocking, there is a logical “1” at pin 9 of DD1.4, and “O” at the output of DD1.4. Transistor VT6 closes, relay K1 releases and disconnects the battery from the power part of the converter. In case of polarity reversal when connecting the battery, relay K1 does not operate at all.
Automatic switching to backup power. If there is voltage in the network, relay K2 is turned on and with its contacts connects the load directly to the network. The optocoupler transistor VU1 is open, and through R14 it supplies a logical “1” to the blocking input. The converter is blocked.
When the mains voltage fails, relay K2 releases, switching the load to the converter output. The optocoupler transistor closes, and a logical “O” appears at pin 5 of DD1.3. Then at the output DD1.3-"1", a positive pulse opens transistor VT5, C5 is discharged, "1" disappears from the blocking input, and the converter starts.
Switch S1 "On" allows you to turn off the converter in the case when, in the absence of voltage in the network, backup power is not required; "+" power is supplied through switch S1 and R14 to the blocking input. When the contacts of switch S1 are opened, the converter starts up - the same as after a power failure in the network.

When working with step-up converters, follow safety rules since the work is carried out with a voltage dangerous to the body!! During the process of setting up the assembly, it is advisable to insulate the output secondary winding with rubber tube cambrics to avoid accidental contact.

Microcircuits K176IE8 And K561IE8- decimal counters-divisors. They have 10 decrypted outputs QO...Q9. The counter circuit contains a five-stage high-speed Johnson counter and a decoder that converts the binary code into a signal at one of ten outputs.

If there is a low level at the EC counting enable input of the K561IE8 and K176IE8 counters, then the counter performs its operations synchronously with the positive edge at the clock input C. If the level at the EC input is high, the action of the clock input is disabled and the counting stops. When the reset input R is high, the counter is cleared to zero.

At each decoder output, a high level appears only for the period of a clock pulse with the corresponding number. The counter has a transfer output C out. The positive edge of the carry output appears after 10 clock periods and is used as a clock signal for the next decade counter. The maximum clock frequency for counters K561IE8 and K176IE8 is 2 MHz.

The duration of the counting prohibition pulse must exceed 300 ns, the duration of the clock pulse must not be less than 250 ns. The reset pulse duration must exceed 275 ns. Possible logical and pulse states of the K561IE8 and K176IE8 counters are summarized in the table.

A foreign analogue of the K561IE8 microcircuit is the microcircuit CD4017A.

K561IE8 - technical data

Status of meters K561IE8 and K176IE8

In order to obtain the counting result in the decimal system at the output of the counter, it was necessary to assemble a circuit of two microcircuits - a counter and a decoder. But besides counters and decoders, there is another type of microcircuit - counter-decoder, containing in one housing both a counter and a decoder connected at the output of the counter. One of these most common microcircuits is K561IE8 (or K176IE8). The microcircuit contains a binary counter, the count of which is limited to 10 (when the tenth pulse arrives at its counting input, the counter automatically goes to the zero state), and a binary-decimal decoder, which is turned on at the output of this counter (Figure 1).

The K561IE8 (K176IE8) microcircuit has the same housing as the K561IE10, but the purpose of the pins is, naturally, different (only the power pins are the same).

Fig.2
To study the functioning of the K561IE8 (K176IE8) microcircuit, assemble the circuit shown in Figure 2. A pulse shaper is made on the D1 chip, it is exactly the same as in the experiments in lessons No. 7 and No. 8.

The pulses arrive at one of the inputs of the D2 chip, in this case at the CP input (positive pulse input), while a logical one must be applied to the second CN input (negative pulse input). You can also apply pulses to the input of negative pulses - CN, but for this you need to apply a logical zero to the CP input.

The R input is used to force the counter to the zero state (one is applied to the R input using the S2 button), while the output “0” of the D2 chip (pin 3) will be one, and all the others will have zeros. Now, pressing the S1 button, using the P1 multimeter (or voltmeter, tester) monitor the change in levels at the outputs of the microcircuit.

The unit will be at the output whose number corresponds to the number of pulses received at the counter input (the number of presses on S1). That is, if you started from zero, then after each press on S1 the unit will move to the next output. And as soon as it reaches the 9th (pin 11), the next time you press S1 it will go to zero again.

The K561IE8 chip counts up to 10 (from zero to nine, and goes to zero at the ninth pulse), but it may need to count up to another number, for example, up to 6. It is very simple to limit the counting of this microcircuit; you need to connect a wire to its input R (pin 15) with the output at which the counting cycle should end.

In this case it is output 6 (pin 5). As soon as microcircuit D2 counts to 6, a unit from this output will go to its input R and immediately set the counter to zero. The microcircuit will count from zero to 5, and when the sixth pulse arrives, it will go to zero, and then again in a circle.

Thus, the conversion factor (division factor) of the K561IE8 microcircuit can be set extremely simply - by connecting one of its outputs to its R input.

Fig.3
Assemble the circuit shown in Figure 3. The multivibrator on elements D1.1 and D1.2 generates pulses with a frequency of 0.5-1 Hz, these pulses are sent to the input of microcircuit D2, and ones appear alternately at its outputs. These units light up the LEDs VD1-VD10. It turns out that the light point runs from top to bottom (according to the diagram) - the LEDs light up one by one. You can limit the count at any time by using wiring to connect input R to any output, for example, pin 5.

The K561IE8 (K176IE8) chip has one more output, designated “P” - this is the transfer output. It is necessary in order to organize a multi-digit counter system, for example, when you need to count not ten, but a hundred pulses. Then one microcircuit will count units of pulses, and the second will count tens. The output works like this: after setting zero, there will be one at this output, and this will happen until the microcircuit counts five pulses, then zero will be set at this output, and it will be until the microcircuit counts to 10 and spreads to zero.

It turns out that at this output, over the entire counting period of the microcircuit, one negative pulse is formed, the completion of which indicates that the microcircuit has counted to 10. This pulse can be applied to the CN input of another K561IE8 (K176IE8) microcircuit, and this other microcircuit will count dozens of pulses received at the input of the first. And the total conversion factor will be 100. You can turn on the third microcircuit after the second (counting up to 1000), and the fourth after the third (counting up to 10000), etc.

Converting binary code to decimal is good, but how can you tell a person in a convenient form what number is at the output of the counter - connect a light bulb to each output of the decimal decoder, and sign the number on it? Agree, this is inconvenient, although thirty years ago this indication method was common.

Look carefully at the display of any electronic digital watch. For each number on the display there is a field on which seven segments (not counting the comma) are located in a special way - either luminous “dashes” - LEDs (if the display is LED), or fluorescent cathodes of luminescent indicators, or color-changing “dashes” of a liquid crystal display.