The post explains a simple LED flashing beacon circuit which exactly simulates arotating police beacon lightby generating alternating pulses of suddenly rising and fading illumination effect on the connected LED. The idea was requested by Mr. Ankit Agarwal
Technical Specifications
Can you advice on how to make the following circuit A single flashing LED circuit, in which the LED flash simulates that of beacon ie when the LED flashes, first it glows slowly, then to full intensity, and then fades.
这给出了旋转灯塔或飞机尾巴上的灯的效果。电路旨在在汽车中使用（作为闪烁的后灯），因此电路可能在12V上起作用，LED可能足够明亮清晰可视化，以便可能是1瓦SMD LED。
Kindly advise
谢谢
The Design
The proposed idea of a single LED rotating beacon lamp simulator can be implemented using the above shown circuit.
Here the IC 4017 and the IC 555 together are configured to generate a sequential chasing high logic across the 10 pinouts of the IC 4017.
The IC 555 is wired as a standard astable which feeds the clock or the flashing signal at pin14 f the IC 4017.
The IC 4017 responds to these clocks and generates a shifting high logic across its 10 outputs from pin#3 to pin#11.
These pinouts are integrated via individual diodes, and the common terminal can be seen connected with the base of a TIP122 transistor.
This transistor includes a 1 watt LED across its base emitter points which enables it form an emitter follower configuration with the LED.
This means that the LED will be supplied with a voltage level that may almost equal to the base voltage of the TIP122, and if this varies, the LED supply can be expected to vary accordingly.
The resistors connected across all the shown outputs of the IC 4017 is selected with an incrementing order or in way such that it forms an incrementing potential divider with reference to the preset resistance which may be seen across the base and ground of the TIP122.
因此，随着4017 IC在其引脚上产生转移或追逐高序列，带有预设电阻值的电阻在TIP122晶体管的基础上产生相应增加或减少电势差。
反过来，这种效果允许在整个LED之间产生不同的电势差，这对此做出了响应，并产生了所需的突然上升和衰减效果，反之亦然，对LED模拟旋转的信标光线。
The speed at which this happens can be set or adjusted with the help of R2.
The light intensity on the LED can be adjusted by suitably setting up the preset at the base of the TIP122 transistor.
The values of the resistor across the pinouts of the IC 4017 may be selected and swapped as per the user preference for generating different random flashing effect with due experimentation.
A rough simulation effect of the above explained rotating beacon simulator circuit using LED may be witnessed as given below.
An easier and cheaper alternative for a revolving LED beacon light can be seen below, although the effect may not be as impressive as the above design.
Please note that you may have to play with the 10K, 1K and the capacitor values to get the most desirable revolving lamp effect from the above circuit.
Simple Emergency Flasher
The next emergency lamp flasher can be used for distress calling, during a car accident or car breakdown:
Dear Sir, many thanks for promptly building the schematic.
如果所需的效果是闪光灯的1个周期，则在10-15秒或更高的情况下停顿，然后又一个闪存周期等等，在组件值中应进行什么可能的更改
Dear Ankit, for that you may do the following steps:
remove the diode and resistor from pin11, and make it blank
next, connect pin13 to ground through a 2.2M resistor
Now connect pin11 with pin13 via a 470uF capacitor, (+) to pin11, (-) to pin13
Can an LDR be added in this circuit so that the flasher functions automatically after dark.
Kindly advise
you can add the last circuit from the following link and use it to keep the above circuit switched OFF during daytime
//www.addme-blog.com/2012/01/how-to-make-light-activated-activated-day-night.html
Dear Swagatam
Please inform the function of R1, C3, R15 and 1000µF.
Dear Abu-Hafss,
the 1000uF is not required, I forgot to remove it in the simulation.
C3 is for resetting the IC 4017 on power switch ON, but here this may not be required so it may be removed…R15 is for enabling the C3 resetting action, therefore it can also be removed and pin15 can be directly connected to ground
先生，我对电路设计感兴趣。我想从你那里了解更多。
Hello sir,
Please sir can you modify this
控制AC 220伏特灯泡的电路
Ubaid, it can become much complicated due to the inclusion of a PWM stage and a MOCxx opto coupler stage…
谢谢you sir for answer.
Hi Swagatam,
电路中R1的价值是什么?
此致，
Nélio.
Hi Nelio, R1 is not required, you can do without it, I lifted the drawing from one of my other application designs, and forgot to remove it for this design.
Hi,
谢谢for your replay. I remember this circuit. Replacing R5-R14 with trimmers what would be the maximum value? 10K? Considering TIP122, I can connect 2 LEDs in series, right?
此致。
NA
Hi, yes the preset can be 10K, it's basically for setting up the base voltage for the TIP122 such that it varies from the minimum LED fwd drop value to the max LED fwd drop value….for two LEDs this could be from minimum 5V to a maximum 7V
the above range should be uniformly distributed across the 10 outputs of the 4017.
Hi,
In the original circuit you miss a 1000uF capacitor, but present in the simulation! Is it needed? Since I'll be using 2 standard LED's, can I replace TIP122 by another ref., smaller, that can withstand both LED's?
此致。
Nélio.
1000UF可以试验以平滑褪色效果，尽管它不是那么重要……。
Swagatam, this post section was not loading and I posted my question in the simple wind generator post.Now I think I have my answer after reading Nelio's comments! Thanks for your time
Cuyler, sometimes this happens, if you refresh the page and try then mostly it will start loading normally again, anyway I am glad you found the solution
Can I connect a 6no 4pin RGB LEDs in place of 1Watt led. What modification to do for that?
please first build and confirm with a 1 watt LED then we will proceed with RGB
que valores son las resistencias 5 17
You can use 1K for R5—R14
Sir,
Can I have a modified version of above rotating beacon circuit with two numbers of 10 watts or less LED lamps with adjustable/selectable On/Off (ie 20 or 30 flashes etc) period?
Hi Pradeep, you can use two TIP142 in parallel and put two 10 watt LEDs at their emitter terminals for getting the effect. For speed adjustments you can tweak the R2 pot.
Sir,
谢谢for your prompt and swift reply. My requirement was bit different, ie, two numbers of LED lamps of 10 Watts each working in a flip flop manner. kindly suggest the modification to be carried in your given circuit.
谢谢
Pradeep，您可以尝试以下概念：
//www.addme-blog.com/led-obstruction-light-circuit/
Eliminate the entire LDR stage along with D1/D2.
And replace R9/R10 with 10uF capacitors for getting a slow fade effect
感谢您是否可以将巡回赛的成就更新为注释。因此，我们可以在不介绍的情况下组装。
I have updated the drawing at the bottom of the post!
首先，感谢您将其放在这里并帮助同胞发烧友。我想知道是否有实际电路运行的视频？在购买零件并构建零件之前，我想确保效果是我想要的。谢谢你。
There’s no video at this moment, however The circuit should work perfectly according to my understanding.