When power is applied, the 15K resistor and 10uF cap at pin 15 will reset the counters to the zero count where pin 3 is at +12 and all other outputs are at zero. The 2 diodes (1n914) and 15 resistor form a AND gate so the clock pulse will be passed to the right side counter when the sequence starts. When the right counter reaches the 10th count, pin 11 will move high enabling the AND gate on the right to pass the clock pulse to the left side counter. As the left side counter advances, pin 3 will be low so that clock pulses cannot advance the right counter. When the left counter turns over and pin 3 again moves high, the sequence will repeat. Thus we get 18 total counts, 9 from the first counter, and 9 from the second.
Note that the 4017 counter will not deliver much current, and so the LED current is set to about 6mA using a 1.5K resistor in series. For more current, you could use transistors on each output as shown in the drawing above, (10 Channel LED Sequencer). But some of the newer bright LEDs are fairly bright at 6mA.
Circuit Design:
The circuit is fairly easy and un-complicated. It uses 2 555 timers and 1 4017 Decade counter. One 555 control the flash rate for the led sequence (decade counting frequency) and the other is to turn the decade counter on and off. Once the led have gone up and down the row once (2 seconds) we switch the power to the 4017 off for 2 seconds and then back on again for another 2 seconds creating a break between each light chase. Fairly simple hey!
Parts:
1x 4017 16 DIL IC | 2 x 555 8 DIL IC |
6x Red LEDs or any of your choice | 2x 10uF Elec Caps |
3x 10nF Caps | 1x BC547, BC108 etc NPN transistor |
6x 1K resistors | 1x 100K resistor |
1x 7K resistor | 1x 110K resistor |
1x 4K7 resistor | 1x 3.3K resistor |
| Circuit diagram for standard LED output. | |
 | |
HOW IT WORKS |
| The 555 timer IC is connected for Astable Operation, the clock pulses are fed to the 4017 IC via the 10K resistor. The 4017 is a 10 stage counter, each of the outputs is connected to the appropriate LED, as some LEDs need to be on for more than one count, we use diodes to avoid a short circuit situation between outputs. The capacitor and resistor on pin 15 of the 4017 are used to reset the counter to zero at initial power up. |
The 4017 counter is a highly versatile and easy to use device. It counts from 0 to 9 and gives the result on one of its 10 output pins. In the dice circuit, the count range needs to be restricted to the range 0 - 5 (six separate numbers) by connecting output 6 to the reset pin. For simplicity, the example circuits use a virtual 2KHz test signal. For a real circuit, you need to replace this with a signal from a fast astable.
| } | ress SW1 to 'roll' the dice |
The circuit shown is for low current LEDs which give good illumination from CMOS outputs. e.g. Rapid part no. 56-0415 Standard LEDs will give disappointing light output unless they are driven by transducer drivers. CircuitWizard does not (as yet) include low current LEDs in its gallery so R3 has been set to 180R. With low current LEDs you can set R3 to 1K.
Note: As only one LED can possibly be on at one time, only one limiting resistor (R3) is required.
This circuit is easily modified to produce a heads or tails game by:
| ¡ | Omitting D3 - D6 |
| ¡ | Moving the reset connection from output 6 to output 2 |
The circuit above above makes use of the CMOS 4017 decade counter IC. Each depression of a switch steps the output through 0 - 9. By coupling the output via an AND gate to the next IC, a predefined code has to be input to create the output. Each PBS switch is debounced by two gates of a CMOS4001 quad 2-input NOR gate. This ensures a clean pulse to the input of each CMOS 4017 counter……
The 4017 is a Complementary Metal Oxide Semiconductor (CMOS) Integrated circuit with sixteen pins, implementing a divide-by-ten function with ten decoded outputs and a carry output. Reset and Count Enable inputs are provided in addition to the Clock input. The pin functions are:
It will work comfortably within a supply voltage range of 3V to 15V. If you try to run it at anywhere over 18V, it might get destroyed.
It will normally count every time the voltage at pin 14 swings from low to high, provided pin 13 is low and pin 15 is not high. The flash animation below might give you a feel of how it works. Click the power switch to start the action!
Just to be complete, the chip will count if the enable input goes high while clock is low. The two inputs are complementary.
If you try to wire this in actual practice, there are a few things to be aware of:
Here are a few solutions to the clock generation problem:
For the greatest speed and reliability you will need to use a double throw switch and two gates in a bistable configuration. The cross connection of the gates ensure that when the switch makes contact and then bounces, the state gets latched and that the output stays steady. From the diagram at left, that is the output A. When the double throw switch is deemed an unnecessary luxury and a slow speed of operation is acceptable, the R-C debounce network followed by a schmitt trigger to sharpen the slow transition may be used. This is the output at B. When you need a continuous train of pulses you can wire up the simplest possible oscillator circuit using a schmitt trigger gate and a resistor and capacitor. Increase the value of the capacitor to make it slower. Or make the resistor variable for an adjustable speed. This is the output at C
The remaining two gates show the preferred way to deal with unused CMOS inputs on a gate package: connect to ground, the supply or to an output which is at a defined level. The CD40106 is a hex schmitt inverter. Quite useful, and able to banish quite a few vexing problems when applied properly. The TTL equivalent is 74HC14, if you need a faster gate. |
Fig 1 4017 Pin-out
The 4017 decade counter is a highly versatile device. It counts positive going edges on the ‘clock’ input and stores the result. The value of the stored count is presented at the ‘decoded’ outputs O0 – O9. The outputs are normally low except for the output that corresponds to the stored count. On the tenth count, ‘carry’ changes from low to high and the counter resets to 0. Carry provides a facility for counting larger numbers; it should be connected to the clock input of the next stage (or digit).
For normal operation, ‘inhibit’ should be held low; making it high stops the counter responding to clock pulses. ‘Reset’ should be held low; making it high resets the counter to 0. At power switch-on, the counter may store a random number. To ensure a zero count, a power-up reset circuit is required (fig 2). +V is the power supply to the whole circuit controlled by SW1. When SW1 is closed, the output to the 4017 reset pin goes high (because C1 is discharged). After a time period (set by R1 x C1) the reset signal decays to a low allowing normal operation of the counter.
The 555 Astable generates a clock for this circuit, an oscillator giving a square wave output at pin 3 which is counted by 4017 to give a running lights effect.
The decade counter-divider CD4017 has 10 outputs, for every low to high transition at the clock input, rising edge, the counter advances one LED. After going one full circle the the first LED lights again and it goes on. You can vary the value of R2 100K Linear potentiometer to make LEDs run fast or slow. The frequency of oscillation of astable 555 is given as f = 1.44 / ((R4 + 2 * (R2 + R3)) * C3)
The 10 outputs have 10 green LEDs. The current thru the LED is limited by R1, the current can be calculated like this (9V - 1.6V) / 1K = 7.4mA this is within 20mA which is the danger limit of the CMOS output. You want it to be bright use transistors for every output.
The cap C1 is a filter and C2 is to prevent noise at pin 5 influencing the output as it is a control voltage point.
You can cascade or chain many more counters with the CO or carry out pin 12 of 4017. The pin 15 reset is kept at low for counting, on high it will reset the counter but is not used in this circuit.
This is Circuit MOSQUITO REPELLANT.
By High Frequency Sound.
Use a electronics part ,easy to find and low cost.
To See Circuit, have IC 555, 4017, 4011 and BC337,BC327.
Output Piezo Speaker.
Volt suppy +12V.
Easy to build see PCB:
