Hi,
I am interested to make a very simple circuit. I have DC voltage from 10V to 15V in my home in which i want to add this circuit on it .I want that a 3mm (Red led) may blink after every 1 or 2 sec when it is connected with the circuit.Definitely there will be need of capacitor and resistor etc etc. If any one knows how make to make this circuit with diagram I shall be thankful to him. Currently i am using breadboard for testing and 9 volt batter i am using with it .
Thanks in advance.

 

So, you want a LED to flash when it is connected to your ~12V supply?

The simplest solution is to use an LED with an integrated flasher. Then all you need to do is connect it to the supply.

Alternatively a 555 chip and a few components will flash an ordinary red LED. Or even a discrete relaxation oscillator.

 

Yes i shall connect it with 12.5V DC supple so in that case with 555 chip can someone help me for the diagram .

 

Here's the datasheet for a 555. The circuit you want is Section 7.4.2 Astable Operation. You would connect a 12V LED to the 555 output, or an ordinary LED with a 1k series resistor: https://www.ti.com/lit/ds/symlink/lmc555.pdf.

Alternatively, here's a discrete circuit I have often used. Not many more components than the 555 circuit:

 

about https://www.google.com/search?chann...+red+led+flash+duration+at+dispersed+daylight

an overkill circuit the exact values for resistors depend on both TYPE and instances (hFE values) of the transistors used
you can do by single comparator https://www.ti.com/product/TL391B-Q1 or 18V CMOS Schmitt inverter https://www.onsemi.com/pdf/datasheet/mc14584b-d.pdf ← 6x outputs in parallel gives ? some 50 mA drive ?

 

slight tweak to boostbuck circuit in #4:
added C2 so that LED does not light up immediately (you wanted 1-2sec delay).
added R6 to make LED go fully off (optional).

 

If any one knows how make to make this circuit with diagram I shall be thankful to him.

Is this schoolwork?

 

one low component count option is to use Schmidt trigger NAND gate. then one input can be used to make an oscillator (input to output resistor, input to GND capacitor). the other input can be used to make delay input to Vcc resistor, input to GND capacitor). and bonus is one still gets three more gates for whatever purpose. of not used, connect their inputs to gnd. load (LED and resistor) from output to Vcc.
if the space is concern there are single gate ICs in SMD though they are only good for up to 5 or 6V meaning there would be need to use voltage regulator or zener...

 

Here you go. Adjust R1 for desired frequency.

 

Thanks all for your valuable support .Really appreciate it .Well currently i am a beginner and want to start from small/baby projects.MrChips you have draw a very simple circuit. will try it . I shall try it on LTspice first then do on my breadboard

 

it will not work in LT spice. models in LTspice do not handle accurately transistor behavior when reverse biased.

 

Hi Gar
It will not work on LTS, as the reverse breakdown voltage is not specified to match a real 2N3904.
E

 

Thanks all for your valuable support .Really appreciate it .Well currently i am a beginner and want to start from small/baby projects.MrChips you have draw a very simple circuit. will try it . I shall try it on LTspice first then do on my breadboard

Don't be surprised if your simulation doesn't work. That circuit relies on exceeding the reverse breakdown voltage of the collector-emitter junction and many simulation models don't model it.

 

Thanks once again for guiding me.What about proteus software for testing purpose .
Well I shall try it on my breadboard

 

Thanks once again for guiding me.What about proteus software for testing purpose .
Well I shall try it on my breadboard

It's not the software, but the device model.

If you find a model for the transistor that accurately models the collector-base breakdown and reverse active regions, then the simulation can yield good results. But these are regions that very few circuits operate in and manufacturers don't spend much time modelling them, instead they often use unrealistic parameters for these characteristics.

Also, the behavior of the transistor with an open base is much more complex than the SPICE models are designed for and so models that are intended to apply to this case are actually subcircuits that are crafted to have the desired behavior.

This is actually something that is pretty common in high-fidelity device models. The MOSFET model for the IBM 130 nm CMOS process was actually a subcircuit with over three hundred components. I know because I looked at it naively thinking that I could tweak it to fit our operating regime -- a notion I gave up the moment I opened the file.

 

Hi,
I am interested to make a very simple circuit. I have DC voltage from 10V to 15V in my home in which i want to add this circuit on it .I want that a 3mm (Red led) may blink after every 1 or 2 sec when it is connected with the circuit.Definitely there will be need of capacitor and resistor etc etc. If any one knows how make to make this circuit with diagram I shall be thankful to him. Currently i am using breadboard for testing and 9 volt batter i am using with it .
Thanks in advance.

Hi there,

Since you mentioned the 555 timer and other versions were given already, here is a version of a 50 percent duty cycle oscillator using the 555 timer. Not much to it if you want to use this device. Be sure to read the text.
In the formulas, a space is treated as a multiplication. If that's not clear I'll add some dots to show multiplications.

I include a little historical data (ha ha) because I got the original drawing (right side of image) from the back of the package that the 555 timer from Radio Shack came in back in the early 1970's I think it was. They often put a little data on the back of the carded parts they sold that they hung on hooks in the stores.

The clearer drawing I redid so it can be viewed easier. The original text on the card was not that good and the camera I used long ago did not have very high resolution. I don't think I have the actual card package anymore either.

 

You can just buy a 1 Hz flashing LED 3mm Red for a few cents, Here is one such example.
A simple Google of "3mm blinking led" will bring up a few dozen examples.

Ron

 

Here's the datasheet for a 555. The circuit you want is Section 7.4.2 Astable Operation. You would connect a 12V LED to the 555 output, or an ordinary LED with a 1k series resistor: https://www.ti.com/lit/ds/symlink/lmc555.pdf.

Alternatively, here's a discrete circuit I have often used. Not many more components than the 555 circuit:
View attachment 366704

An example of a D. A. N. D. Y. Circuit.
Discretes are not dead yet

 

if you play/tinker around with the Joule Thief self-feedback and bias capacitors you can achive a different flashing modes - if you got a common mode input choke for/from some (blown) mains AC-DC adapter it will bare you from winding one (an auto TF for the blocking oscillator)

 

You can just buy a 1 Hz flashing LED 3mm Red for a few cents, Here is one such example.
A simple Google of "3mm blinking led" will bring up a few dozen examples.

Ron

Hi Ron,

I got a few of the 'flickering' LEDs that look like candles. Now they actually make candles with those LEDs inside so they look like candles. They have a lot of different sizes from very small 1 inch diameter 1 inch high to 3 inch diameter and 6 inches high. It got quite a few of them. I also got the non flickering types. I highly recommend them for power outages as they run for several days and you can place them on the floor so you can see where you are walking. Some of the non flickering ones die down faster though sometimes just 24 hours, but they take regular coin cell batteries too so easy to change.