Sequencer circuit

Posted on Feb 6, 2014

First, the 4017`s aren`t initialized to a known state since the reset pins aren`t briefly forced high when the circuit powers on. The chips might usually power up in the normal reset condition, but that isn`t probably guaranteed by the IC manufacturer. This is probably only a minor concern. Second, on the IC2 4017, outputs Q2 through Q9 are shorted together and tied to the reset pin.

Click here to download the full size of the above Circuit.

This is a major design flaw. This appears to be an attempt to modify the design of the lower schematic you provide. In that design, there are only 20 outputs used, and when IC2 toggles Q2 high, that high will reset IC2 back to Q0 being high. In your upper schematic, if you are really using all 10 banks of outputs on IC2, none of the outputs need to feed back to the reset pin. Regardless, only certain types of logic can tolerate outputs being shorted together, and the 4017 isn`t one of them. Third, tying an output pin back to the asynchronous (instantaneous, not on a clock edge) reset pin creates what is called a race condition. The width of the reset pulse will only be as long as the propogation delay from the reset pin to the output pin driving it. While this might work, there are a lot of circuit designers who wouldn`t do that. This is also probably only a minor concern. I agree with Cat that a 4017 can`t drive the positive side of a relay. Doing so might work for some reason (as the relay clicks in Janneman1`s video seems to prove), but unless you are using extremely sensitive relays that take little current to energize them, you are violating the output drive spec of the 4017. I don`t know - maybe it works for very short relay pulses, or maybe the chip will put up with this for a while, but this is another major concern. Cat, the 555 schematic you pasted in isn`t the right one. That schematic is the monostable mode...

Leave Comment

characters left:

Related Circuits

Make this Fancy LED Tail Ring Light Circuit for your Car

The following article describes a fancy LED sequencing/diverging ring type light which can be used as a tail brake light in cars. The circuit idea was requested by one of the avid readers of this...

RS232 Reset for Microprocessor

This circuit allows a remote microprocessor to reset the control of a host by sending an interrupt signal on an RS-232 or RS-422 serial line. If the remote machine is restarted on a simple program...

Infrared Cordless Headphone Amplifier

Using this low amount Project one can carbon AUDIO from TV after advancing anyone. It does not use any wire amid TV and HEADPHONE. In abode of brace of affairs it uses airy Infrared ablaze to...

XR2212 PLL FM demodulator Circuit

A simple PLL FM demodulator circuit using IC XR2212 is shown here. XR2212 is a highly stable, monolithic PLL (phase locked loop) IC specifically designed for communication and control system...

Circuits Diagram: Simple 40W inverter

This is the schematic of a simple 40W, 12 to 220 V inverter. You don`t believe, this is simple and cheap and working for me for last 4 years. The heart of the circuit is a CD 4047 IC which is wired...

SimpleCircuit IF Signal Generator

Here is a able ambit of IF arresting architect which may be of absorption to radio hobbyists and professionals alike. Transistors T1 and T2 anatomy an astable multivibrator aquiver in the audio...

Simple variable frequency oscillator circuit

Single Differential Input Adapter for Digital Voltmeter

I some cases, a cogwheel ascribe is bare for voltage measurement. Using the alone one operational amplifier, you can body an adapter to accommodate a amphibian ascribe for your ground-referenced...

New Circuits

Zero consumption Anti-theft High power Code Switch for E-Bike Batteries

This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
Ultrasonic distance finder circuit

The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Simple Metal detector circuit with CD4030

Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Fully automatic watering circuit for flower pots

Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
Simple deep searching metal detector circuit

The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
Sub-Harmonic Bass Converter for Electric Guitars

The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
Echo Depth Sounding Sonar for Boats

In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
100W HiFi Audio Amplifier Circuit

This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
Plant-Pot Water Level Indicator Circuit

A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....

Create NOW your QR MENU for your Restaurant / Hotel / Bar / Caffe,

Comprehensive ordering/paying features. fully personalized to suit your Business.

Update Anytime! Easy and Simple!

Popular Circuits

Ear Protector Circuit

The ear protector is actually a peak audio-detector/shutdown circuit that disables the amplifier...

ZN414 Portable AM Receiver circuit and description

Designed around the popular ZN414 ic this receiver covers the AM band from 550 - 1600 KHz with...

studio synth circuit

I originally wanted to call it Chimera , but then I remembered there`s already a synth company...

Remote Alarm For Smoke Detector

This alarm circuit was designed to monitor a mains-powered smoke detector located in a shed...

Simple Indicator for Dynamic Limiter Schematic Diagram

The indicator described here is specifically designed for adjusting the dynamic limiter described...

led workbench lighting

A very useful workbench lighting unit for electronics hobbyists. The portable inspection lamp...

ttl three state logic probe circuit

The circuit presented here usesNAND logic gates of Hitachi HD seriesIC HD74LS00, which is a quad...

electronic toggle switch no1

This simple circuit will energize and de-energize a relay at the push of a button. Any type of...

compressor microphone

The FM Remote Control Receiver` (available on this website in Infra-red circuits section) has a...

IR remote control computer interfacing

This article tries to get you some idea how to interface IR remote controllers to computer....

Data-Logger Shield for Arduino

There is a small power supply on the board for generating 3. 3V @ 250mA. We don`t use the `built...