# Need help to design an automatic on off on off circuit

#### arpitagarwal82

Joined Jul 23, 2019
1
Hello guys
I like to build decor lamps and lights using led.
One of my project requires a special circuit.
I want leds to glow for 5 seconds after every 60 seconds. So it will be an on-off repeated cycle.
How can I do this?

Please explain it in a way that a lay man can understand.

#### AnalogKid

Joined Aug 1, 2013
8,139
Pretty simple circuit.

What is the operating voltage available for the circuit?

What is the LED voltage and current being switched?

What is your skill set for assembling a small circuit on perf board?

A CMOS 555 (LMC555) circuit can do this, but I'm not a fan of it for loooong cycle times.

Also, there are cycle timer modules on ebay for cheap.

ak

#### MisterBill2

Joined Jan 23, 2018
4,019
A simple way to have 5 seconds on and 45 seconds off would be to drive the LED switching transistor, (MPSA13) with one output of a 4017 decade counter with a simple 555 timer delivering a pulse every 5 seconds. An added effect can come from using the other outputs for other 5 second intervals. While the circuit has a few parts it has the advantage of not being tricky to make it work. Adding a second stage counter could provide the exact 5 seconds on and 60 seconds off. '
How exact are the time requirements?

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#### AnalogKid

Joined Aug 1, 2013
8,139
I want leds to glow for 5 seconds after every 60 seconds.
5 seconds AFTER every 60 seconds (65 second total period)

or

5 seconds IN every 60 seconds (60 second total period)

???

ak

#### Janis59

Joined Aug 21, 2017
790
1) The 555 twin-brother 4060 is much better suited for long time operations up to the several hours.
2) Yet those 5 seconds bay be well made by 555 monostable

Joined Jan 15, 2015
4,581
Hello guys
I like to build decor lamps and lights using led.
One of my project requires a special circuit.
I want leds to glow for 5 seconds after every 60 seconds. So it will be an on-off repeated cycle.
How can I do this?

Please explain it in a way that a lay man can understand.
If you plan to be doing this with several projects and maybe using various LED effects like color changes and LED fade in and out you may want to think about using some small uC (micro controller) circuits rather than discreet components. While circuits can be built with discreet components you can buy micro controller chips at a few bucks each and learn some very basic programming to get some nice visual effects. There are also countless code samples online to get started.

Regardless of how you go about this many of the questions asked need answered. Things like LED types, their current and voltage requirements as well as other questions. Those are key parameters which need to be known to give you any advice.

Ron

#### MisterBill2

Joined Jan 23, 2018
4,019
A CD4060 oscillator plus BINARY counter is not at all close to a 555 device. I addition, it requires decoding the binary count for most intervals. In addition it has a much lower maximum output current.
Using a micro controller will be perhaps a hundred times more complicated and it will cost a lot more, be much larger, and use a lot more power. In addition it will give you much less experience dealing with real-world challenges.

#### AnalogKid

Joined Aug 1, 2013
8,139
Using a micro controller will be perhaps a hundred times more complicated and it will cost a lot more, be much larger, and use a lot more power.
Agree about the complexity, especially for a "lay man". Disagree with everything else.

I have a pretty consistent opinion that microcontrollers (uC's) are way overprescribed on forums. And, I think a 4060 circuit is the best approach (although a CMOS 555 still is a contender if the timing tolerances are loose enough). But in this case, no other approach will cost less or have fewer components than a microcontroller, and some of the newer ones have power levels that are comparable to CMOS. Note that (except for whatever the output is driving) most of the current in a 4060 circuit is drawn by the oscillator, and a low power PIC is pretty much equivalent.
In addition it will give you much less experience dealing with real-world challenges.
Totally agree.

ak

#### MisterBill2

Joined Jan 23, 2018
4,019
Agree about the complexity, especially for a "lay man". Disagree with everything else.

I have a pretty consistent opinion that microcontrollers (uC's) are way overprescribed on forums. And, I think a 4060 circuit is the best approach (although a CMOS 555 still is a contender if the timing tolerances are loose enough). But in this case, no other approach will cost less or have fewer components than a microcontroller, and some of the newer ones have power levels that are comparable to CMOS. Note that (except for whatever the output is driving) most of the current in a 4060 circuit is drawn by the oscillator, and a low power PIC is pretty much equivalent.

Totally agree.

ak
A 5 second pulser plus a ring counter is all it would take to deliver the sequence the TS is requesting. 3 IC devices plus the R and C for the 555 device. That is simple and the big benefit is that it does not need any programming at all.

#### AnalogKid

Joined Aug 1, 2013
8,139
A 5 second pulser plus a ring counter is all it would take to deliver the sequence the TS is requesting. 3 IC devices plus the R and C for the 555 device.
Or a single 4060 plus three diodes and an output transistor. To be clear, I'm not advocating a uC; just the opposite.

ak

Joined Jan 15, 2015
4,581
Using a micro controller will be perhaps a hundred times more complicated and it will cost a lot more, be much larger, and use a lot more power. In addition it will give you much less experience dealing with real-world challenges.
I don't know. While I have never been a major fan of using a micro for every solution I only mention it being something to consider. The lowly PICAXE 08M2 chip runs about $2,70 and would be well suited for several LED task including fade in and out as well as color change with a RGB LED. A prototyping board runs about$3.50 allowing the user to setup as many chips as they wish. Yes, the programming aspect, even in basic, is a bit of a challenge but not really all that difficult with likely hundreds of code samples out there online. I merely pointed it out as another option, that's all it was.

Since the original poster never returned with more information as to any LED specifications there isn't much which can be said.
"In addition it will give you much less experience dealing with real-world challenges".
What real world challenges? The original poster wants simple which a lay man can do. Does not seem he or she is pursuing a career in electronics but rather focusing on only building decorative lamps and lights using LEDs. Anyway, it's just another option I figured the original poster could consider rather than building his projects with discreet components.

Ron

#### AnalogKid

Joined Aug 1, 2013
8,139
Based on very little information, here is the basic timer, modified from another design for another forum. This has a fixed on-time-to-total-cycle-time ratio of 5:64.

Adjust the overall cycle period by changing R1. For a 6:64 ratio, move the D3 cathode to Q8 (pin 14).

The output cannot drive an LED string directly. Adding an output stage depends on more information about the LEDs.

ak

EDIT - Updated the decoding feedback per Kjeldgaard (that dastardly Dane).

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#### MisterBill2

Joined Jan 23, 2018
4,019
Quite a few years back, 19 to be specific, I discovered that what DigiKey was marketing as "high brightness" LEDs would produce a very useful amount of light when driven by a single CMOS output. I think that I was using the Qbar output of a CD4038 to pull down the LED fed with 5 volts. Not a bright light by current standards, but indicating what can be done. Or feed the output to the base of an MPSA13 darlington device and have lots of current to play with.

#### Kjeldgaard

Joined Apr 7, 2016
379
Based on very little information, here is the basic timer, modified from another design for another forum. This has a fixed on-time-to-total-cycle-time ratio of 5:64.
Again one of these nice old-fashioned circuits.

I would suggest saving an active component by moving resistor R3 to one of the diode places, and D1 will provide the lowest power consumption.

#### AnalogKid

Joined Aug 1, 2013
8,139
I would suggest saving an active component by moving resistor R3 to one of the diode places, and D1 will provide the lowest power consumption.
I know that trick, then forget it, then know it again, then ...

Updated the schematic.

ak

Joined Mar 10, 2018
3,609
Using a cheapie Arduino NANO board the program was written in block language
(right hand window) in 1 minute. Program is mBlock, its free. Timing fairly accurate,
2% I seem to remember.

As you learn (lots of videos on mBlock, kids in 6 grade and up using it) you can add
more LEDs, control by pushing a button, measure a temperature or other environmental
and display/control stuff. Kids are controlling robot motion with it.

Lots of fun, you just drag and drop the blocks, pick the pins, and tell it to create and

The block at the top tells the tool that is going to generate the code for you where
the program starts. The forever block says run all the blocks inside its "arms" until
you and I turn to dust. Inside are instructions that turn the pin to high (to light LED,
followed by a wait instruction that leaves the pin high for the wait time, then an
instruction to turn pin low and leave it low for the wait shown after it. Then the
instructions repeated endlessly because of the forever block/loop.

Regards, Dana.

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