Turn signal alarm if left on

I need lots of help. I’m trying design a timing circuit.

I’m hard of hearing and many times I drive down the road with my turn signals going. I have put a buzzer on the turn signals and that works fine. However its aggravating to listen to the buzzer when waiting to make a turn or change lanes.

I’m trying to design a circuit that when I active the turn signal it starts a timer and if after (a adjustable time delay let’s say 15 seconds to one minute). If after that delay the turn signal is still on, the buzzer will sound with each flash until I turn off the signal. Turning off the turn signal at any will reset the timer.

I have looked everywhere for a circuit that would work. I have tried many different 555 Timer circuits but couldn't make any of them work.

I want to use the turn signal as the trigger. That signal cycles between about 4 and 9 volts as measured On my VOM. The meter is too slow to get a good voltage reading.


1. Turn signal on starts timer.
2. Timer times out in 15 to 60 seconds adjustable.
3. Timer when times out energizes a relay (12 Volts) and the turn signal is routed to thebuzzer thus each time the turn signal flashes the buzzer sounds.
4. Any time the turn signal is turned off the timer resets.

Hi. You can try the attached circuit. It should work. The circuit is connected in place of where your existing buzzer is connected.

Things I don't like about it is the large timing capacitor since you have a large time delay period, and the circuit takes a few seconds to reset. The buzzer turns off immediately when you switch the turn signal off, but if you switch the turn signal back on again without waiting for a few seconds, it will alarm before the designed delay period is reached, the time delay depending on how long you did wait. The time delay period is approx. equal to the product of R1 and CT if the circuit is allowed the few seconds to fully reset. Also, your buzzer should not draw more than 100 mA, or else a buffer transistor and a couple of resistors need to added. If an electromechanical buzzer then an inverse diode must be placed in parallel with the buzzer.

I thought of maybe using a counter circuit to count the flasher pulses. That could work too.

I can try to explain what i have thought to do:

When the lever is not activated, the zero output goes into an inverter transistor setup to charge a capacitor. The same lever output goes into a transistor to bias it to allow current to flow from the charged capacitor once it is activated.
It acts as a charge, discharge circuit for the capacitor, and the transitors are the switches for it.
Then take the pulse that is generated from discharging of the capacitor and send it to a monostable circuit, calculate the R C values to get the delay time that you want. After the circuit discharges you need the buzzer to sound.
Take the output from the monostable circuit, and invert it using a transistor circuit, then take that output and give it to an AND gate setup with the other input to the AND gate from the lever as is

This setup will make the monostable circuit receive a single pulse only when the lever is activated to avoid another input trigger

Not sure where to connect the turn signal. Right now one leg of the buzzer is connected to ground. The postive side of the buzzer is connected to the turn signal lamp socket thru a diode (1N4001).

Where you have +12V is that connected to a 12 volt constant supply; and -V connected to ground all the time. The signal from the turn signal goes where?

I'm 68 years old and know very little about circuits.

Thanks for all your help. I can build the drawing just don't understand where to connect the turn signal signal V+ or V-
I think the time period can be obtained with a 500K pot and a 100 MF cap.

Thanks again for all your help.
RexOfNapa@comcast.net sends

Stumped said:

Not sure where to connect the turn signal. Right now one leg of the buzzer is connected to ground. The positive side of the buzzer is connected to the turn signal lamp socket thru a diode (1N4001).

Where you have +12V is that connected to a 12 volt constant supply; and -V connected to ground all the time. The signal from the turn signal goes where?

I'm 68 years old and know very little about circuits.

Thanks for all your help. I can build the drawing just don't understand where to connect the turn signal signal V+ or V-
I think the time period can be obtained with a 500K pot and a 100 MF cap.

Thanks again for all your help.
RexOfNapa@comcast.net sends

Click to expand...

You're welcome. That's fine. Just connect the +V and -V terminals to the same places that your existing buzzer terminals are connected, making sure that the +V terminal is connected to the junction of your existing lamp socket diodes and the -V terminal is connected to ground. Edit: You'll need to continue to use your existing diodes so that the circuit works with either turn signal.

Since your existing buzzer has one side grounded it looks like your turn signal relay switches the +12V power side to power your turn signal lamps. What I usually see in autos is that the turn signal relay switches the ground side of the turn signal lamps. But no matter. The attached circuit doesn't care. Leave your existing diodes leading from the lamp sockets in place and substitute the attached circuit for your existing buzzer only.

Thanks for posting the schematic for the time delay one shot using the 555. I did a little playing with the time constant cap and resistor values to get a 45 second delay, but otherwise everything else is the same. Just perfect for a turn signal warning alarm!

My yamaha Fj1200 had a turn signal reminder from the factory, it used a reed switch on the back of the speedo, it was an old mechanical speedo with a rotating magnet.
A counter counted the pulses after so many a buzzer went off in time with the inidcators.
Newer bikes like cars use a vehicle speed sensor, usually 4 pulses per rev, you could use this maybe with something like a 4040 binary counter and latch a relay that controls a buzzer.

You might google self-cancelling turn signal. i remember seeing an aftermarket self-cancelling turn signal for vintage automobiles that didn't have turn signals. Can't put my finger on it. They use an accelerometer to self cancel. I saw some for motorcyclles when I searched.

Basing the warning on time isn't necessarily good ether.