Vehicle turn signal reminder circuit

Claim 1

A turn signal reminder circuit for connection to the signalling circuit of a vehicle, the signalling circuit including (1) an electrical power source having two terminals, one of which is grounded to the vehicle body, (2) a flasher switch, a double throw left and right turn signal switch and left and right turn lights serially connected to the power source, and (3) a brake light switch and brake lights serially connected to the power source, the turn signal reminder circuit comprising: (a) an astable multivibrator timer circuit for generating an asymmetrically switched output at an output terminal and having a pair of power supply terminals, a first one of its power supply terminals adapted for connection to a first terminal of said electrical power source; (b) an electrically controlled switch having a control input terminal and a pair of switched terminals, one of the switched terminals being connected to the second terminal of the power source and the other switched terminal being connected to the second one of the multivibrator power supply terminals; (c) a filtering circuit for converting voltage pulses from the flasher switch to a continuous voltage, the filtering circuit having an input and having an output connected to the control input terminal of the electrically controlled switch; (d) a sound transducer circuit having one terminal connected to the output terminal of the astable multivibrator timer circuit and another terminal connected to the input of the filtering circuit at a common input node; (e) a disabling circuit connected between the common input node and a node between the brake switch and the brake lights for resetting of the timer circuit upon actuating of the brake; and (f) an enabling circuit connected between the common input node and a node between the flasher switch and the double throw switch for initiating and maintaining operation of the timer circuit.

Claim 7

A method for warning a vehicle driver that the vehicle's turn signals may have been inadvertently left activated, the method comprising: (a) moving a signal switch from a neutral to a signalling position to initiate turn signalling; (b) converting electrical signal light flasher pulses to a continuous enabling signal; (c) effecting the astable switching of a multivibrator timer between a first occurring longer-time, partial cycle and a shorter-time, partial cycle, in response to said continuous enabling signal; (d) enabling an alarm during each said shorter-time, partial cycle; and (e) actuating the alarm by the flasher pulses when the alarm is enabled; and (f) disabling the alarm and resetting the timer in the event of operation of a vehicle brake or the return of the signal switch to the neutral position.

Claim 8

A method for warning a vehicle driver that the vehicle's turn signals may have been inadvertently left activated, the method comprising: (a) moving a signal switch from a neutral to a signalling position to initiate turn signalling; (b) converting electrical signal light flasher pulses to a continuous enabling signal; (c) effecting the astable switching of a multivibrator timer between a first occurring longer-time, partial cycle and a shorter-time, partial cycle, in response to said continuous enabling signal; (d) enabling an alarm during each said shorter-time, partial cycle; and (e) actuating the alarm by the flasher pulses when the alarm is enabled; and (f) disabling the alarm and resetting the timer in the event of operation of a vehicle brake or the return of the signal switch to the neutral position.