Main battery disconnection alarm and headlight warning circuit

A main battery disconnection alarm and headlight warning circuit in which the main battery charges and maintains a backup battery in full charge, and when the main battery is disconnected or damaged, the backup battery provides power to an alarm and a control circuit triggers a siren to give warning, and a headlight warning circuit which triggers a siren to give a different warning sound from the main battery disconnection alarm.

BACKGROUND OF THE INVENTION 
There are many kinds of burglar alarms for installation in vehicles. Most 
of them are powered by the vehicle's main battery, and will not function 
if said main battery is damaged or disconnected. Moreover, forgetting to 
turn off the ignition switch or the headlights before leaving the vehicle 
will deplete the battery, but there may be no warning to the owner of this 
situation. In view of the above defects, the inventor has created a main 
battery disconnection alarm and headlight warning circuit. 
SUMMARY OF THE INVENTION 
The present invention provides a main battery disconnection alarm and 
headlight warning circuit which uses D1 and R2 to charge and maintain a 
back-up battery in a fully-charged state; R1, R4, R5, C1, and IC1 to cause 
IC2 to output "0" when the main battery is operating properly, and to 
cause IC2 to have an output of "1" when its input is "0,0" within a time 
determined by R6, R7, and C2 after disconnection of the main battery so 
that the backup battery provides power to operate a alarm and trigger a 
siren; and IC7 to give an output of "1", causing IC3 to output "0" to 
trigger an oscillation circuit composed of IC5, IC4, C7, C6, R20, and R18 
if the vehicle's headlights continue to light for a pre-determined period 
after turning off the ignition switch in order to give a warning distinct 
from that of the main battery disconnection alarm.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
The present invention provides a main battery disconnection alarm and 
headlight warning circuit, in partioular a warning system to prevent the 
cutting off of the vehicle's power source by persons other than the 
vehicle's owner, and to prevent the vehicle's owner from forgetting to 
turn off the vehicle's headlights after the vehicle's engine is shut off. 
The main battery disconnection alarm and headlight warning circuit, 
according to the present invention, is characterized by: (1) A backup 
battery which supplies power to a vehicle alarm system in the case that 
the vehicle's main battery is disconnected, damaged, or drained of power; 
(2) an output to a siren which is triggered when the main battery is 
damaged or disconnected by someone attempting to defeat an alarm system or 
vandalize the vehicle's electrical system; (3) the alarm system and the 
headlight warning circuit are powered by the backup battery when the main 
battery is disconnected or damaged; (4) a warning can be given if the 
vehicle's headlights are not turned off before leaving the vehicle; and 
(5) simple installation. 
The present invention is described in detail with reference to the attached 
drawings. 
FIG. 1 is a block diagram of a preferred embodiment according to the 
present invention. As shown in the drawing, the main battery (1) charges 
the back-up battery (3) via a charging circuit (2) so that the backup 
battery (3) maintains a full charge as a standby power source to the alarm 
(4). Normally, the alarm (4) is powered by the main battery (1), but the 
alarm (4) is powered by the backup battery (3) if the main battery (1) is 
disconnected or damaged. The present invention includes a main battery 
disconnection alarm circuit (5) which gives an audible warning using power 
from the backup battery (3) when the main battery is disconnected or 
damaged. 
Headlight lit signal (6), vehicle ignition key switch (8), and bypass 
signal (7) are sent to the headlight. warning circuit (9). If the 
headlights (6) remain lit after a preset time after the vehicle ignition 
switch is shut off, the headlight warning circuit (9) causes the siren to 
give a warning signal. 
FIG. 2 is a circuit diagram for the preferred embodiment of the present 
invention. As shown in the drawing, point A connects to the positive 
terminal of the main battery, point B supplies backup power to the vehicle 
alarm, point C connects to the positive terminal of the backup battery, 
point D connects the negative terminals of both the main and backup 
batteries, point E connects to a manually-controlled bypass switch, point 
F to the headlights, and point G to the ignition key. The main battery can 
charge and maintain full charge of the backup battery via D1 and R2. The 
backup battery is of conventional structure and not within the scope of 
the claim herein. The main battery gives a signal to IC1 and IC2 from R1 
via R4. After phase reversing at IC1, then D3, R6, R7, and C2 give a 
signal to IC2. R7, R6, and C2 compose a delay circuit. After disconnection 
or damage of the main battery, IC2 will have an input of "0,0" and an 
output "1" during the time predetermined by R6, R7, and C2. This signal, 
after phase reversing at IC3, IC5, IC4, C6, C7, R20, and R18, which 
compose an oscillator, turns on Q1 and RY1 to trigger a siren in order to 
give a warning signal. RY1 in the present invention connects to a siren 
which is of conventional structure and not within the scope of the claim 
herein. 
A signal from the headlights is sent to IC3 via R9, R10, R11, and C4. When 
the ignition switch is in the "off" position, the input at point G is "0". 
When the ignition switch is in the "on" position, input at point G is "1". 
After phase reversing at IC6, and under control by the delay circuit, 
input to IC7 changes to "0,0", and the output becomes "1" after the end of 
the delay period. When the headlights are lit, input to point F is "1", so 
that input to IC3 is "0,1", output is "0" and the oscillator composed of 
IC5, IC4, C7, C6, R18, R19, R20, and D8 turns on Q1 and causes generation 
of a signal to warn that the headlights have not been turned off. After 
turning off the headlights, output at point F is "0", so that output of 
IC3 is "1" and no warning will occur. Point E is a bypass circuit to allow 
the headlights to be turned on when the ignition key is Off Input of a "0" 
signal at point E resets R9, R10, R11, and C4 without triggering the 
alarm. The headlight warning circuit, according to the present invention, 
gives a series of relatively quiet and short intermittent sounds to 
prevent noise pollution and to distinguish it from the main battery 
disconnection warning. The main battery disconnection warning gives a 
series of longer, full-volume intermittent sounds to threaten would-be 
burglars.