• Skip to primary navigation
  • Skip to main content
  • Skip to primary sidebar

Homemade Circuit Projects

Get free circuit help 24/7

  • +1000 Circuits
  • Hobby Circuits
  • Basic Circuits
  • Learn Arduino
  • Logic IC Pinouts
  • Disclaimer
You are here: Home / Sensors and Detectors / Car Turn Signal Flasher Circuit with Lamp Malfunction Indicator

Car Turn Signal Flasher Circuit with Lamp Malfunction Indicator

Last Updated on June 29, 2020 by Swagatam 15 Comments

The post discusses an automotive/car turn signal indicator circuit idea with a built-in load malfunction indicator, meaning an additional LED lamp fitted on the dashboard which would warn if any of the side indicators went bad or fused. The idea was researched and requested by Mr. Abu-Hafss.

The Circuit Concept

I have found a transistor-based flasher including a relay, online

Physically, the circuit oscillates when a Load is connected across the pin "C" of the relay and earth. If the load is less than 100 Ohms the oscillation is significantly fast. And if the load is say about 1K the frequency is normal.

However, I could not understand the circuit nor it is simulating in LT Spice. Could you please explain me how the circuit is sensing the change in resistance of the load. And could you please make the simulation work.

OBJECTIVE:

To make a 555 based automotive turn signal flasher circuit which can detect lamp outage. If not possible with 555 then transistors may be considered.

CIRCUIT – A:

Above are the photos and schematic of the circuit. I have physically tested it. It also works on BC558/BC546.

With bench power supply of 12V-2A and load connected at pin (L) and (-), following is the behavior:

· No load, no oscillation

· Pin (L) and (-) shorted, very fast oscillation (relay sounds)

· Load 1 – 1.5K, normal oscillation (about 1.4Hz)

· Load increases, oscillation slows

· Load decreases, oscillation decreases

When using a car battery and 3 x 27W bulbs in parallel the circuit oscillates normally. Even, if a bulb is removed the frequency is unchanged. This means, this circuit does not detect lamp outage. However, the behavior of the circuit with a bench setup may give you some clue to my objective.

CIRCUIT - B

Yesterday, I came across this circuit which has a relay to detect load. I have not yet tested it. I hope this circuit might also help us. Maybe we can replace the relay with a transistor.

Thanks for your help.

Abu-Hafss

IC 555 based car turn signal indicator with pilot warning lamp:

The required circuit design which is shown below may be understood with the following points:

The IC 555 section is wired in the normal astable multivibrator whose  pulse rate at pin## can be adjusted with the help of the given 100K pot.

The two NPN transistors function as current sensor, and IC 555 reset controller.

When power is switched ON, the N/C contacts of the relay connect the turn signal lamps with the 12V supply.

The lamps light up and in the process draw the required amount of current via the Rx resistor.

The above current develops some voltage across Rx which triggers the left BC547 transistor and switches OFF the right BC547 transistor.

The above action resets the IC 555 so that it starts pulsing the relay and the connected lamps.

The LED at its N/O contacts also starts blinking in accordance indicating the correct presence of the lamps at the front and the rear side of the car.

Rx value must be selected such that it develops just sufficient voltage across it to trigger the transistor in response to current consumed by two lamps at the specified rates.

In case even one of the lamps malfunction, the voltage across Rx then wouldn't be high enough to trigger the transistor.

This situation would keep the entire circuit frozen, also keeping the warning LED shut off, providing the necessary malfunction indications to the driver.

SHARING IS CARING!



Previous: Digital Voltmeter Circuit Using IC L7107
Next: Timer Controlled Exhaust Fan Circuit

About Swagatam

I am an electronic engineer (dipIETE ), hobbyist, inventor, schematic/PCB designer, manufacturer. I am also the founder of the website: https://www.homemade-circuits.com/, where I love sharing my innovative circuit ideas and tutorials.
If you have any circuit related query, you may interact through comments, I'll be most happy to help!

You'll also like:

  • 1.  Electronic Scoreboard Circuit Using IC 4033 Counter
  • 2.  Car Tank Water Sensor Circuit
  • 3.  Electronic 12V DC Capacitive Discharge Ignition (CDI) Circuits
  • 4.  Car Head Lamp Fader Circuit (Breathing Effect Generator)
  • 5.  Transformerless Automatic Night Lamp Circuit
  • 6.  How to Manufacture Automobile Electronic Parts and Earn a Handsome Income

Please Subscribe (Only if you are Genuinely Interested in our Newsletters)


 

Reader Interactions

Comments

    Your Comments are too Valuable! But please see that they are related to the above article, and are not off-topic! Cancel reply

    Your email address will not be published. Required fields are marked *

  1. Search Related Posts for Commenting

  2. Patrick Puxley says

    Thanks for the car flasher circuit. If the lamps are connected directly to earth as is normal in car indicator circuits, can the current sensing transistor (left hand) be connected at a location physically closer to the module, say, on the positive side of the lights before the indicator switch
    Would the circuit have to amended elsewhere
    Thanks
    Patrick

    Reply
    • Swagatam says

      Hi, which circuit are you referring to? Is it the IC 555 one? Anyway yes you can do that without any amendments.

      Reply
      • Patrick Puxley says

        Yes, the 555 circuit.
        Sorry, I saw your note about replying to the correct thread, but it isnt obviuos where the correct place is.
        Although I see the circuit has now been ammended somewhat from the one I was initially referring to, with a diode on the base of the LH BC547 (from a 22uF cap).
        Thanks for your reply

        Reply
        • Swagatam says

          Yes you can place the current sensing stage near the lamps. I have improved the design slightly to ensure that the leftmost transistor remains switched ON even during the OFF periods and allows the 555 flasher to work normally.

          The note is to remind the users not to be off-topic while commenting. Your comment is perfectly related to the article topic so it’s more than fine.

          Reply
          • Patrick Puxley says

            Hi
            I have the circuit working now as drawn, but I cant make it work with connection point for the sensing circuit (LH transistor) on the positive side of the switch (obviously!). The problem is that in a realworld motorcycle solution the lights go directly to earth on the negative side and the indicator toggle switch is physically remote from the flasher unit.
            Need to sense current flow in the positive side of the switch when the indicator switch is closed.
            This is what the physical layout is
            https://flic.kr/p/2irVTbc
            What am I missing?
            Thanks for your help, Im enjoying the learning. This is purely for interest ,because its possible to buy electronic flasher units quite reasonably……..its become a challenge!
            Patrick

            Reply
            • Swagatam says

              Hi, thanks for the feedback,
              you can probably try modifying the design in the following manner:

              555 car flasher with lamp detector indicator

            • Patrik Puxley says

              Thanks. I sort of thought of that but was worried about how large the resistor would be, in series in the lamp circuit. Lamp circuit will be running at 4A (2x21W+5W =47W/12V= about 4A.) Is that right?

            • Swagatam says

              If the lamp current is 4 amps then the resistor can be approximately calculated using the following formula:

              Rx = 1.2 / 4 amps

  3. Swagatam says

    It's my pleasure Abu-Hafss,

    In your circuit it could be because of the large value capacitor, not sure though? Otherwise your simulator could be giving wrongs results because any astable circuit may it be using an opamp or any other similar device will never produce an initial delay when switched ON.

    Reply
  4. Abu-Hafss says

    Hi Swagatam

    Thanks, your appreciation is really like an award for me 😉
    You may post it in your blog.

    The configuration of my op-amp oscillator is almost same as the one shown in figure 29. The only difference is that my design has extra resistor R4, which if removed does not result any change in the output.

    Reply
  5. Swagatam says

    Hi Abu-Hafss,

    please try simulating the Fig29 "square wave oscilltor" shown the following datasheet of LM324, I am interested to see the simulation results:
    http://www.ti.com/lit/ds/symlink/lm124-n.pdf

    Reply
  6. Swagatam says

    I'll check the opamp design and try to solve it, if possible…

    Reply
  7. Swagatam says

    Hi Abu-Hafss,

    Great idea! This will surely work. I'll post it in my blog if you don't mind Mastermindji.

    Thanks for this idea!

    Reply
  8. Abu-Hafss says

    Actually, I wanted to use a single IC for the circuit preferably LM324. Two op-amps for the lamp outage detection and one for astable oscillator. However, I faced a drawback.

    https://dl.dropboxusercontent.com/u/20969135/Op%20Amp%20Astable.gif

    Here is the sq. wave oscillator circuit with an op-amp, frequency 1.4Hz. But as you can see in the simulation, the oscillation starts after about 6.5s. Is there any way to avoid that?

    Reply
  9. Abu-Hafss says

    Hi Swagatam

    First of all, please spare time to increase the headings of your so that it is easy to find some particular old posts. I understand it is time consuming but, it will quite helpful. It took me quite some time to locate this post. You can also increase one heading "Automotive projects".

    Ok, now here is the circuit which I designed for the car signal flasher with bulb outage detection function.

    https://dl.dropboxusercontent.com/u/20969135/Flasher.gif

    https://dl.dropboxusercontent.com/u/20969135/Flasher%20Circuit%20description.pdf

    I had completed this design long time ago but, forgot to report you Ustaad jee.

    Reply



Primary Sidebar

Electronic Projects Categories

  • 3-Phase Power (15)
  • 324 IC Circuits (19)
  • 4017 IC Circuits (51)
  • 4060 IC Circuits (25)
  • 555 IC Circuits (94)
  • 741 IC Circuits (18)
  • Amplifiers (49)
  • Arduino Engineering Projects (82)
  • Audio Projects (85)
  • Battery Chargers (76)
  • Car and Motorcycle (88)
  • Datasheets (45)
  • Decorative Lighting (Diwali, Christmas) (32)
  • DIY LED Projects (82)
  • Electronic Components (97)
  • Electronic Devices and Circuit Theory (35)
  • Electronics Tutorial (100)
  • Fish Aquarium (5)
  • Free Energy (34)
  • Games (2)
  • GSM Projects (9)
  • Health Related (17)
  • Heater Controllers (24)
  • Home Electrical Circuits (98)
  • Incubator Related (6)
  • Industrial Electronics (27)
  • Infrared (IR) (39)
  • Inverter Circuits (94)
  • Laser Projects (10)
  • LM317/LM338 (21)
  • LM3915 IC (24)
  • Meters and Testers (55)
  • Mini Projects (153)
  • Motor Controller (65)
  • MPPT (7)
  • Oscillator Circuits (15)
  • PIR (Passive Infrared) (8)
  • Power Electronics (33)
  • Power Supply Circuits (65)
  • Radio Circuits (9)
  • Remote Control (46)
  • Security and Alarm (56)
  • Sensors and Detectors (116)
  • SG3525 IC (5)
  • Simple Circuits (72)
  • SMPS (29)
  • Solar Controllers (60)
  • Timer and Delay Relay (51)
  • TL494 IC (5)
  • Transformerless Power Supply (8)
  • Transmitter Circuits (39)
  • Ultrasonic Projects (12)
  • Water Level Controller (46)

Follow Homemade Circuits

Facebook
Twitter
YouTube
Instagram
My Facebook-Page
Quora

Feeds

Post RSS
Comment RSS

Circuit Calculators

  • AWG to Millimeter Converter
  • Battery Back up Time Calculator
  • Capacitance Reactance Calculator
  • IC 555 Astable Calculator
  • IC 555 Monostable Calculator
  • Inductance Calculator
  • LC Resonance Calculator
  • LM317, LM338, LM396 Calculator
  • Ohm’s Law Calculator
  • Phase Angle Phase Shift Calculator
  • Power Factor (PF) Calculator
  • Reactance Calculator
  • Small Signal Transistor(BJT) and Diode Quick Datasheet
  • Transistor Astable Calculator
  • Transistor base Resistor Calculator
  • Voltage Divider Calculator
  • Wire Current Calculator
  • Zener Diode Calculator
  • Privacy Policy
  • About Us
  • Contact
  • Disclaimer
  • Videos – Circuit Test Results

© 2021 · Swagatam Innovations