This is a tutorial with calculator to help learn the application of 555 which is a very rare chip innovation. It is simple, versatile, flexible and programmable (by tweaking of pots).
Astable 555 Timer Flasher – Interactive demo
The 555 Astable oscillator gives a square wave output at pin 3, The output drives two LEDs, LED1 lights up when pin 3 is low and LED2 when pin 3 is high.
The 555 can source (LED2) or Sink (LED1) upto 200mA. It can even drive a small motor or lamp with diodes added to protect from inductive kickback. Vary Ra, Rb and Ct and see the change of frequency, period and duty cycle.
The CD4020BC, CD4060BC are 14-stage ripple carry binary counters, and the CD4040BC is a 12-stage ripple carry binary counter. The counters are advanced one count on the negative transition of each clock pulse. The counters are reset to the zero state by a logical “1” at the reset input independent of clock.
CD4040BC, 12-Stage Ripple Carry Binary Counters
CD4060BC, 14-Stage Ripple Carry Binary Counters
CD4060 – 14-Stage Ripple Carry Binary Counters
you can also use a crystal between pin 10 and 11 with two caps 22pF from 10, 11 to gnd and a 10M resistor between 10 and 11 in place of R C network for more precision.
This was a attempt to make a Sequential Timer with ICM7217 of Intersil, even though it worked well, it was not developed beyond the prototype stage or first iteration. Only when a product is made in some numbers, the documentation and designs become clear, streamlined and seasoned.
The PCB and Circuit are not complete. It may give ideas. During this time, as far as i can remember, these were the only large CMOS devices. 8080-85 and Z80 devices consumed lot of power and needed big boards and supplies.
ICM7217 4-Digit, Presettable, LED Up/Down Counter Maxim
Study this, if you are not good at firmware or you need a simple solution, this is still a versatile chip. It is better you make your own PCB. This board can be used for prototyping only.
Timer Circuit pdf
Clock Circuit pdf
The MM5369AA and 3.579545 MHz
I have converted from DOS Orcad to Windows, corrected some mistakes, use with care. Orcad on DOS had a very user friendly interface, it had a near windows like GUI on DOS, when windows did not even exist, It had right mouse button controls too.
It is called analog dial timer as it has no digital display, but the chip is digital it is CD4541. It is Mains operated, you could make on-delay or off-delay. By changing the caps and resistors or with even dip-switches you could get timing of few seconds to many hours. Circuit is Analog Timer 4541 .
Some timers energize the relay after a set delay on power start. Some start with relay energized and turn off after set time. Motors and big systems cannot take fast turn-on and turn-off, Some systems will require sections or modules to start one after another as they are interdependent. So Timers in automation were made to effect such delays, the early ones were mechanical clockwork.
The CD4541BC Programmable Timer is designed with a 16-stage binary counter, an integrated oscillator for use with an external capacitor and two resistors, output control logic, and a special power-on reset circuit. The special features of the power-on reset circuit are first, no additional static power consumption and second, the part functions across the full voltage range (3V¨C15V) whether power-on reset is enabled or disabled.
- Available division ratios 28, 210, 213, or 216.
- Increments on positive edge clock transitions.
- Built-in low power RC oscillator.
- Oscillator frequency range . DC to 100 kHz.
- Power on Auto reset initializes all counters.
This is an example of a cascaded or sequential timer, here two CD4541 are forming a two stage timer. You can add more in a chain, but better to use a microprocessor or Microcontroller for such a purpose. But make sure EMI-RFI immunity is high for these circuits or wrong resets and sets can make a machine like an Oven or Environment Chamber malfunction and even ruin the job.
Two Stage Sequential Timer – del90004
U5B a flip-flop is used for the control switches Start and Stop to prime or shutdown the sequential cycle. The first timer U2 sets the flip-flop or register U5A after a period T1, this register turns the relay on thru Q3. The second timer U4 which was triggered by the first will reset the U5A after time period T2, U5A then shuts down relay. U5A also then resets entire process thru U3C and U3D.
U1 CD4541 is a Timer with Long Duration Ability. This timer is started by a low pulse from earlier circuit, when the temperature goes above setpoint, a low state is at U2A inputs, this starts the timer. The timer output goes high after a preset time. U2C-D Flip flop is power on reset via cap C7. Even a manual ‘reset’ is used if required. This alarm toggle is ‘set’ when The temperature remains high even after the preset time period of U1.
Timer and Counter Modules – del90002
A digital counter monitors the number of times a process goes beyond a certain temperature limit over a long cycle of time. This circuit has a Analog Timer and Digital Counter. The Analog timer turns on an Alarm if the Temperature Limit transition is very long.
When i had put the near Obsolete digital circuits online in the late nineties. One person who works in a public institution in the usa, wanted a modification of one of my existing circuits. He had those parts the CD40 Series Logic Chips. He wanted to use only those that he had in his Stock.
I made some modifications and sent it to him, that helped him with his task. These things can be done very easily using the Arduino. One could make a programmable Arduino Timer/Counter with a matching Configuring Software without coding, for such people. Easy and Affordable.
Digital Circuits 2 from delabs
Circuit 1 – Digital Timer Clock With Preset using Thumbwheel switch.
A Thumbwheel Switch has to be used in place of DIP switch shown, just know that 1-2-4-8 nibble (4 bit) should be generated by Thumbwheel switch at preset or jam inputs of 4029.
Use CD4511 if 4513 is not available, but circuit has to be changed a bit around 4511
Circuit 2 – 1 Hz or 1 pps crystal clock using CD4060 and 32768 Hz Crystal.
They have not been tested much… The 4513 control pins 8-4-5-3 connections verify, as i did not get the datasheet.
The circuits will work as the concepts are right, but some tweaks in R C values may be required.
the R C values can only be corrected if you have problem in making it work.
The main problem in the R C values may be related to “the reset at 6 for the tens of seconds and the tens of minutes”.