The 4017 decade counter has ten outputs which go HIGH in sequence when a source of pulses is connected to the CLOCK input and when suitable logic levels are applied to the RESET and ENABLE inputs.
The 4017 IC
The 4017 takes a clock pulse in and then steps the output from negative to positive in a series of ten steps, with only one pin being on at a time. It has the unique capability of counting up to a certain number and then restarting the count, counting up to a certain number and halting, or it can be cascaded to more 4017's for a higher count.
The outputs are labeled 0 through 9. It can sink about 10 ma. of current per pin and is a very versitile IC. It operates from 3 VDC. to 15 VDC.
18 Stage LED Sequencer
18 Stage LED Sequencer
The question sometimes comes up of how to cascade 4017 decade counters for more than 10 sequencial stages. The LED sequencer below shows a possible solution using a few extra parts.
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.
Authentic Looking Knight Rider Led
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 |
Knight Rider Lights Project
| Circuit diagram for standard LED output. | |
 | |
You can use 12V bulbs for the output, simply substitute the IC for the LEDs, the bulbs are then connected to the IC's outputs.
This set up is ideal for running off a car battery.
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. |
Basic 4017 dice
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 |
Digital Combination Lock by IC 4017
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……
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