Change impulse signal to the straight signal


I have an impulse signal from my car turn light and i want to change it to the straight signal without the pulses. I heard about multivibrator like C4047

Anybody knows how to plug it ? I knows where put the VCC but how about the impulse signal and rest things?


Google: bistable multivibrator images.
For Arduino you will have to have 5 volt o/p.
Will need to reset the bistable with your code.

Well... i need a straight/stable for the transmitter/relay which in one way will power the Arduino, and in other way the other thing. If it is not necessary i would like to avoid the Arduino for drive the multivibrator, beause i will need to add another chip for the board with arduino. Is there a easer way to drive the multiwibrator, by resistor or potentiometer or other device ?

The turn lights pulse is a very long time duration looking form Arduino.
You can very easily have an if statement in your loop() to ask if an input has become high.
Then save this state in a global, and do your code.

At some point you will need to start over, then you reset your state varaibale and look for a change on your input again.

Very easy to do, as you can almost directly use the "Button" example found here.

Ok Anders i can read it because i know the english but i cant figure out what to think about what i read :smiley:

I ill be straight as possible.

In case of arduino than multiwibrator.
i recieve the pulse signal to the arduino, and when the arduino sense the signal it will send the stable signal to the output. The 5V will be enough to drive the transmitter/relay! but arduino also need after sense the singal delay it because the signal will be high and low in loop. So how can i make it ? i will put it on the Attiny85 maybe.

Here is the logic. Suppose t is the time between blinks (where a blink is the input active time). Any time the input is active, enable the output. If the input has been inactive for greater than time t, disable the output.

It's not more complicated than that.

Now i understand. Do You saw over here similar project? i am a very greeny in Arduino case.

anybody... ?

If a pulse turns the light on, how does it turn it off ? A 555 monostable will only go high with a negative input signal. If you need it to toggle ON with the first pulse and OFF with the next you need a


I have an impulse signal from my car turn light and i want to change it to the straight signal without the pulses.

You have the pulsed DC voltage that makes your turn signal blink and you want to get a Full DC Voltage when ever the indicator is being used?

Use a diode, capacitor and a resistor.

Not sure how smooth you need the DC output, what are you aiming to do with the DC?

Tom..... :slight_smile:

flipflop is something different.

I guess you think of such a code (aargs suggestion):

#define BLINKDURATION 1000 // time (ms) to detect blinker is off
#define BLINKPIN 2           // INPUT blinking signal pin
#define STRAIGHTSIGNALPIN 3  // OUTPUT non blinking
void setup() { pinmode(STRAIGTHSIGNALPIN, OUTPUT); }

void loop () {
 static unsigned long lasttime;
 boolean blinking_input = digitalRead(BLINKPIN);
 static boolean output;
 if (blinking_input == HIGH)
   lasttime = millis(); 
   output = HIGH;
   if (millis() -  lasttime > BLINKDURATION )
   output = LOW; 
 digitalWrite(STRAIGHTSIGNALPIN, output);

assuming a properly blinking signal on BLINKPIN ( 5V-0V when blinking, 0V when not blinking)

[ edit : fixed my favorite error getting the elapsed time ]

Can of course be solved in electronics as well.

You have the pulsed DC voltage that makes your turn signal blink and you want to get a Full DC Voltage when ever the indicator is being used?

Thanks TomGeorge,
I didn't know what the OP was talking about until I read your comment above. I still don't know how the OP plans to turn it off.

Helo Guys!

I need stable DC for the relay. The idea is simple.

Turn the turn signal on, the signal going to the Attiny which make the signal stable, then it goes to the 5V relay which in one way turn the day lights off and turn the signal light on, then when the signal will go off then the relay turn itself and the day light will go on.


1 .after attiny detect the signal it make it stable using own power from VIN.
2. Stable signal going to the relay and change its position.
3. after signal is gone more than i dont know, maybe 2 seconds then the attiny turn off the stabilized signal.

Yes Michael, the 12V from the car will be stabilized to the 5V via 7805 stabilizer.

You need a circuit or algorithm called a "missing pulse detector".

This will output one level if there are no pulses and another level if there are pulses.

You can make this with a capacitor that is charging up and a transistor across it that discharges the capacitor when it gets the pulse. Arrange the time constant so that in the absence of a pulse the capacitor charges up to some threshold voltage that triggers a circuit. This could be monitored on an analogue input.

Alternatively you have a software program that records the millis() time on each pulse. The loop then checks how long it has been since the last pulse and triggers a variable if it has been too long.

i wonder whether hardware solution can be enough precise, and how about durability?
Can the capacitor will charge up enough after one pulse, of course i will put the Schottky diode but will be enough?

I think the software solution will be more flexible and precise ?

That one looks interesting...

What is that element on the input?

Statements with question marks on the end are hard to follow.

I gave you good advice from over 40 years in electronics, no one solution is better than another.

I agree, because this is exactly what i am searching for. i am very thankful for that advice!

Do you have any electronics experience ?

Novice, im still learning. I know the basics.

Before Arduino times we did this with a simple cmos IC. e.g CD4538.
AFAIK, the circuit is called a "pulse stretcher".
A re-triggerable mono.
Like this.