Abstract:
An electronic alarm and a vending machine equipped with the alarm monitors a plurality of zones by suitable circuitry to detect vandalism and theft. Each zone has a mechanically-triggered sensor that provides an electrical output. The zones comprise a pair of door sensors and a separate, shock sensor. A solid-state logic circuit includes a red and green indicator light, and a loud warning buzzer ultimately triggered by the sensors. A circuit time delay and logic scheme analyzes sensor status, and separate false-alarm prevention circuits insure proper triggering after a predetermined delay. Alarm status is indicated by highly visible green and red status lights mounted on the door. A buzzer sounds in response to sensor activation and circuit logic. A back-up battery that is coupled to the logic circuitry for fail-safe operation includes an automatic recharge system, and dual red and green LED&#39;s monitor battery condition.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates generally to vending machine alarm systems. More particularly, the present invention relates to alarm-equipped vending machines typically used at self-service car washes that are deployed in unattended locations, and which are subject to relatively high rates of vandalism and theft. 
   2. Description of the Related Art 
   Over the last several years, the self-service car wash industry has greatly modified the quality and quantity of products and services that are offered to customers. Many ancillary products such as vehicle waxes, detergents and other diverse items are sold from self-service “coin-operated” vending machines of diverse sizes, configurations and shapes that are usually mounted conveniently close to the washing bays. (As used herein the term “coin-operated” refers to self service vending machines that accept coins, credit cards, currency, tokens, or combinations thereof). Besides offering the consumer several cleaning options related to the vehicle exterior, typical self-service car wash installations offer a variety of products and choices relating to the vehicle interior. For example, numerous coin-operated suction-applying vacuuming systems exist. Various carpet cleaning and spot removal products are available for more vigorous interior cleaning. Various towels, dashboard cleaning solutions or preparations, various waxes, deodorants, and other diverse automotive items are typically stocked by well-equipped vending installation. Coin-operated vending machines that dispense fragrances and apply them to the vehicle interior are becoming relatively common. 
   In the self-service car wash industry most common coin-operated vending machines are installed outdoors at unattended locations. Of course, industry practice has been to mount the machines as safely and securely as possible within illuminated, high visibility areas. Often, custom-designed concrete “islands” are created at the carwash site specifically for mounting vending machines. Despite the advantages in security that result from specialized mounting designs, the risks of burglary and vandalism are ever-present. Most vending machines comprise a dollar-bill changer accessory, and a coin storage box. Many machine components are viciously mutilated when thieves smash their way through external components trying to break into these components. Although the burglary of money stored within vending machines is significant, the cost of physical damages inflicted upon vending machine structures by thieves during a theft often exceeds the amount of money stolen. As a result of such factors, burglary and/or intrusion warning systems designed specifically for vending machines have been proposed previously. However, known alarms suffer from many disadvantages. 
   Usually burglars try to pry open the vending machine door with a crow bar or other large lever, the use of which results in significant damages. Most of the alarms proposed to date are triggered by a switch at either the bottom or top of the door which is set off when the cabinet door, or a portion of the door, is deflected. However, if the burglar or vandal is attempting to pry open the door at a point below the latch, and if the alarm switch is above the latch, the alarm may not be triggered. Some alarms trigger only after significant structural damages are incurred by the machine. Many alarms require constant attention and complex maintenance by the proprietor. Some alarms are simply too difficult to set and reset. Most importantly, many common systems are prone to frequent, irritating false alarms. 
   SUMMARY OF THE INVENTION 
   Our unique alarm is adapted for installation within an upright cabinet associated with a typical vending machine. The alarm functions with conventional door designs, or with modern multi-point locking systems. A plurality of zones are monitored by the circuitry to detect vandalism and attempted theft. In the preferred mode, each zone includes a suitable sensor that responds to mechanical inputs and provides an electrical output. Preferably the sensors comprise a pair of door monitors and a separate, vibration or shock sensor. A solid-state monitoring circuit carefully analyzes the status of the sensors, providing two separate false-alarm prevention circuits. If conditions warrant it, an alarm is generated in response to the sensors after a predetermined delay time expires. 
   Alarm status is preferably indicated by a green status light and a separate red status light mounted on the machine front (i.e., upon the door or the cabinet). Both status lights are highly visible, so that an attendant need not exit his vehicle when inspecting an installation. Alarm states include an “Idle Mode”, an “Armed Mode,” and a “Detected Mode.” In the idle mode service or maintenance may occur, as the alarm is disarmed. Most of the time the alarm assumes the “armed mode” and guards against vandalism or theft. In response to an intrusion the detected mode is enabled, and audio and visual warnings occur. 
   The circuit includes a buzzer that is activated by the combination of sensor activation and circuit logic. A back-up battery is coupled to the logic circuitry for fail-safe operation. Means are provided to automatically charge the battery, and dual red and green LED&#39;s driven by voltage sensing circuitry indicate battery condition. 
   The alarm preferably comprises a receiver that responds to a portable key-fob unit that an attendant may carry. A separate internal transmitter can remotely relay “detected mode” alarm conditions and status to a central location, but means are provided for relaying warnings via direct wire where required. 
   Thus, a basic object of the invention is to provide a highly sensitive, but intelligent, alarm system suitable for use with modern, self-service car wash vending machines. 
   Similarly, it is an object to provide a secure, alarm-equipped vending machine for vending automotive car-wash products, including vacuum, fragrances, cleaning solutions, and the like. 
   It is also a basic object is to provide a reliable alarm system ideal for car wash vending machines that sit alone in unattended, dimly lit locations that are subject to relatively high vandalism rates. 
   Furthermore, it is an important object to provide an audio-visual indication system for an alarm and a vending machine equipped with such an alarm, emulating the type of alarms used in modern vehicles. Specifically, it is a feature of the alarm that a blinking red light indicates that the alarm is properly set and protecting the machine. 
   Another basic object is to provide a car-wash vending machine that is difficult to successfully vandalize or burglarize. 
   A related object is to provide a vending machine alarm system that recognizes minor jolts or bumps during normal machine operations. It is a feature of the invention that the alarm will not respond to minor, ordinary vibrations of the type encountered in normal use. 
   Another object is to provide a vending machine alarm that can be user-set and reset with a minimum of inconvenience. 
   Another object is to provide an alarm system of the character described that allows a proprietor to drive through an installation with multiple alarm-equipped machines and quickly determine the status of each. 
   Yet another object is to provide an alarm of the character described, and a vending machine equipped with such an alarm, that unambiguously and reliably displays its status. It is a feature of our invention that flashing lights, that may be visually inspected by an attendant as he or she simply drives by the vending machine, brightly indicate the alarm state. 
   Another important object is to provide an alarm of the character described with an intelligence capability that enables the alarm to recognize desired alarm signals indicating theft, vandalism, unauthorized machine movements and the like. 
   It is also an important option to provide an alarm of the character described with a battery recharging system, and a means for warning the attendant or service personnel about the state of the battery and alarm recharging circuitry. 
   Another important object is to provide a transmitter and receiver means for vending machine alarms that enables the alarm to communicate remotely. 
   It is also an important object to provide a vending machine of the character described that is ideally adapted for car wash installations and which is relatively easily serviced. 
   Another object of my invention is to provide an alarm system of the character described that may be advantageously employed in conjunction with a variety of coin-operated vending machines and applicator systems. 
   These and other objects and advantages of the present invention, along with features of novelty appurtenant thereto, will appear or become apparent in the course of the following descriptive sections. 

   
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     In the following drawings, which form a part of the specification and which are to be construed in conjunction therewith, and in which like reference numerals have been employed throughout wherever possible to indicate like parts in the various views: 
       FIG. 1  is a fragmentary isometric view of a vending machine equipped with our alarm unit; 
       FIG. 2  is a block diagram of the preferred alarm system; 
       FIG. 3  is an electrical schematic diagram of the preferred power supply and battery recharging circuit; 
       FIG. 4  is a block diagram of the preferred receiver integrated into the alarm; 
       FIG. 5  is an electrical schematic diagram of the preferred transmitter that is integrated into the alarm; 
       FIGS. 6–9  together form an electrical schematic of the preferred alarm circuit; 
       FIG. 10  is a diagrammatic view illustrating how  FIGS. 6–9  should be positioned for viewing; 
       FIG. 11  is an electronic timing diagram of the preferred alarm circuit showing various signals that are generated within the circuit revealed in  FIGS. 6–9 ; and, 
       FIG. 12  is a pictorial view of the preferred remote control key-fob. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   With initial reference now directed to  FIGS. 1 and 2  of the appended drawings, the preferred vending machine has been generally designated by the reference numeral  10 . It will be appreciated at the onset that the vending machine may be employed to vend a variety of products, and it may include a variety of internal parts, shelves, dispenser arrangements, coin-acceptors, dollar-bill acceptors or other typical accessories and features that are known to those skilled in the art. Vending machine  10  comprises a rigid, upright, cabinet  11  preferably made of stainless steel. The cabinet is normally disposed upon a suitable supporting surface  17  ( FIG. 1 ), which preferably is provided by a suitable, elevated outdoor pedestal mounting of conventional design. Plumbing and electrical connections necessary for vending machines of this genre will be available proximate the mounting island, and often they are wired through the island into the interior volume  16  of the vending machine, as recognized by those skilled in the art. 
   The machine cabinet may be sized and shaped as desired. The illustrated cabinet  11  comprises a separate, frontal section  12  shaped generally like a parallelepiped that is associated with a somewhat cylindrical rear. Alternatively the entire cabinet may be in the form of a parallelepiped. A large, generally rectangular front door  14  is mounted to front section  12  with an elongated hinge  15 . The cabinet  11  has a top  18  and sides  19  that surround cabinet interior volume  16 . When door  14  is closed, the cabinet interior volume  16  will be substantially sealed and protected from the outside environment. As will be recognized by those skilled in the art, a variety of conventional vending machine equipment and components (i.e., such as power supplies, pumps, timers, circuit boards, fuses, wiring etc.) will be protectively housed within interior volume  16 . In some designs, various quantities of physical products to be vended will be stored within interior volume  16  as well. 
   As a preliminary security measure the preferred compound hinge structure  15  enables the door  14  to nest, when closed, within a protective, recessed region of the cabinet offset from the frontal edges of the machine top  18  and sides  19 . The latter construction minimizes machine susceptibility to prying. The hinged front door  14  is manually manipulated during service by a handle  20 . The door  14  is released by a key  21  that moves locking channel section  23 . Preferably, multi-point locking is established by channel  23  that is engaged by the multiple door locking pins  24  ( FIG. 1 ) projecting from the door&#39;s inner surface  25 . This preferred multi-point locking structure is described in co-pending application owned by the same assignee as this case, entitled “Vending Machine Cabinetry With Security Locked Double Hinged Door,” Ser. No. 10/857,078, filed May 28, 2004, which, for purposes of disclosure, is hereby incorporated by reference. Of course it is to be understood that our alarm is intended for use with other vending machine configurations and designs as well, and is not limited to multi-point locking systems. 
   Alarm  28  is securely mounted within the machine cabinet  11  upon a suitable interior panel  29  or other mechanical support. The preferred peripheral circuitry  30  is illustrated in block form in  FIG. 2 . As described further below, alarm  28  monitors and responds to a plurality of separate “zones,” preferably three. The first zone comprises as internal, normally-closed vibration or shock sensor  32  mounted within the cabinet interior volume  16 . Sensor  32  opens only when it senses shock. The two other “zones” monitored by alarm  28  are a pair of normally-open mechanically or magnetically operated door sensors  34  and  35 . These sensors  34  and  35  are preferably mounted to contact the door  14  ( FIG. 1 ) when it is closed. When the door  14  is closed, sensors  34  and  35  “close” to complete a circuit through them. Alarm status is preferably indicated by a green status light  37  ( FIGS. 1 ,  2 ) and a separate red status light  38  mounted atop door interior surface  25 . Status lights  37 , and  38  preferably comprise LED&#39;s. Both are visible from the front of the door or cabinet, once the door is shut, the vending machine is switched “on,” and the alarm is turned “on” and then appropriately “armed.” 
   The alarm  28  may assume three separate states of operation, an “Idle Mode”, an “Armed Mode,” and a “Detected Mode,” that are explained in detail hereinafter. In the idle mode the alarm is disarmed, and service or maintenance activities are possible, as the alarm does not respond to a disturbance. In the “armed mode” the alarm monitors potential vandalism or theft activities or other disturbances to the vending machine, all of which are collectively referred to herein as intrusions, and circuitry to be described processes derived intrusion information. In the detected mode, detection circuitry has confirmed a proper intrusion, the alarm has been triggered, and audio and visual signals are provided. In the idle mode when the alarm is disarmed, a “Disarmed” status is indicated by a steady green light (i.e., status light  37 ). The alarm logic circuitry is discussed hereinafter in detail. Preferred alarm conditions indicated by the status lights  37 ,  38  ( FIG. 3 ) are as follows: 
   
     
       
             
           
             
             
             
           
         
             
               TABLE 1 
             
           
           
             
                 
             
             
               Status of Installed Alarm vs. Indicator light condition 
             
           
        
         
             
               Alarm Condition 
               Red light status 
               Green light status 
             
             
                 
             
             
               Idle Mode, “On” but 
               Off 
               Steady On, machine 
             
             
               disarmed 
                 
               service OK 
             
             
               Machine “armed” 
               On and Blinking 
               Off 
             
             
               Detected Mode (Alarm 
               On and Fast Blinking 
               On and Fast Blinking 
             
             
               activated and tripped) 
             
             
                 
             
           
        
       
     
   
   With joint reference now directed to  FIGS. 2 and 3 , a battery-backed up power supply has been generally designated by the reference numeral  40 . Connector  42  applies twelve volt rms A.C. voltage across diode rectifier bridge  43  that outputs approximately sixteen volts D.C. to line  46  at node  44  across filter capacitor  45 . Line  46  ( FIGS. 3 ,  7 ) delivers voltage to a remote buzzer  254  ( FIG. 7 ). Voltage is delivered through jumper  47  to optional filter capacitor  48  and regulator IC  49  (i.e., a 7805 chip) that outputs regulated five volts D.C. across filter capacitor  50  to line  51 , which runs to the various +5 volt devices. Line  53  connects optional filter capacitor  54  and regulator IC  55  (i.e., a 7812 chip) to the unregulated sixteen volts D.C. appearing at node  44 . Regulator  55  outputs across filter capacitor  56  to +12 volt D.C. source line  57 . 
   A back-up battery  58  is coupled via back-biased diode  59  to node  44  to power the alarm when no A.C. power is available from connector  42 . Battery  58  is physically remote from the alarm unit and it is interconnected to the power supply circuitry  40  with connector  39 . Preferably the battery is secured within the vending machine cabinet. Means are provided to charge battery  58 , and a charge indicator comprising a green LED  68  and a red LED  69  ( FIG. 3 ) is provided to monitor its status. Line  41  from connector  42  ( FIG. 3 ) leads to half-wave rectifier diode  60 , filter capacitor  61 , and series resistor  62  to pin  6  of electrical relay  63  that leads via line  64  and interface  65  to a green LED  68 . Relay contact  6  connects to contact  7  during normal operation so that green LED  68  is normally activated to indicate that battery  58  is fully charged. The companion red LED  69  is activated on line  73  when relay contact  6  connects to contact  5  to indicate that the backup battery  58  is charging. 
   There are two battery voltage monitoring systems ( FIG. 3 ) for controlling recharge operations. Battery voltage is monitored and compared to two reference points via comparators; the first comparator determines when the battery voltage has dropped and recharging is necessary; the second comparator determines when voltage is so low that recharging is unsafe. A recharging circuit uses comparator  74  and a companion recharge-prevention circuit uses comparator  90 . The recharge circuit comprises relay  63  ( FIG. 3 ) which can be activated by switching transistor  71  that energizes relay coil  70  to recharge battery  58  by closing relay contacts  3  and  4 , so current through resistor  52  trickle charges battery  58 . When the battery  58  is not being recharged, relay contacts  6  and  7  are connected, and contacts  2  and  3  are connected ( FIG. 3 ). Transistor  71  can be switched “on” by comparator  74  via resistor  78  and line  76 . With transistor  71  “on,” relay contacts  3  and  4  are connected, and contacts  5  and  6  are connected. Pin  2  of comparator  74  is connected via line  78  to node  79  at the junction of voltage divider resistors  80  and  81  that are connected across battery  58 , to monitor battery voltage. Pin  3  of comparator  74  connects to node  86  at the junction of divider resistors  87  and  88  that are connected to variable resistor  89 , which can adjust the reference voltage appearing at node  86  to approximately 7.97 volts. Comparator  74  seeks to enable recharging when the battery voltage, preferably 13.5 volts, drops too low at node  79 . 
   The recharge prevention circuit ( FIG. 3 ) assumes that the battery cannot be trickle charged, but must instead be replaced or recharged by a high amperage external charger, if battery voltage drops beneath approximately 10.5 volts. In the recharge prevention circuit, pin  6  of comparator  90  ( FIG. 3 ) is similarly connected via line  91  to line  78  to derive battery voltage reading. Pin  5  of comparator  90  leads to a resistance divider node  93  between resistors  94 , and  95  to establish a reference voltage. If battery voltage is too low, comparator  90  turns on transistor  96  via node  92  and resistor  97  to turn off transistor  71 . With transistor  71  “off”, relay coil  70  is “off” and the relay  63  is unswitched. Relay contacts  3  and  4  are disconnected so trickle charging through resistor  52  stops. 
   Charging status is indicated by LED&#39;s  68 ,  69  ( FIG. 3 ). When relay contacts  5  and  6  are connected by activation of transistor  71  during battery charging, red LED  69  is “on” via line  98 , that is thus interconnected to power via resistor  62 . If battery voltage is acceptable to comparator  74 , and recharging is unnecessary, the green LED  68  will be “on,” powered via line  66  ( FIG. 3 ). If the recharge prevention circuit is activated, i.e., comparator  90  is outputting at node  92 , transistor  100  is switched “on” via resistor  101  so the voltage at node  103  across resistor  104  goes low, turning off green LED  68 . 
   Referencing primarily  FIGS. 2 ,  4  and  5 , the alarm portion of vending machine  10  preferably comprises a receiver  112  ( FIGS. 2 ,  4 ), and a separate transmitter  114  ( FIGS. 2 ,  5 ). Receiver  112  responds to remote transmitter key fob  21  ( FIG. 2 ), enabling remote control of the alarm. Transmitter module  114  transmits alarm “detected mode” status remotely, either though radio transmission or by direct wire or both. 
   The receiver module ( FIG. 4 ) responds to key fob  21  ( FIGS. 2 ,  12 ), which is a small, portable unit with built-in authentication mechanisms for security, which is operated by three simple push-buttons described later. Power to the receiver module  112  ( FIG. 4 ) appearing on line  116 , which is coupled to +5 volts via line  51  ( FIG. 3 ), is delivered via resistor  118  to pin  5  of the receiver IC  120 . Chip  120  is a Linx Technologies RXD-315 encodable receiver integrated circuit, and it is programmed by DIP switch  122  that interconnects with chip pins  15 – 24  ( FIG. 4 ) for addressing; i.e., switch  122  matches IC  120  for use with a given key fob  21  ( FIG. 2 ). Pin  28  of receiver IC  120  ( FIG. 4 ) receives RF energy from jack  124  that is connected to antenna  126 . Pin  3  of receiver IC  120  (i.e., labeled “D 1 ” in  FIG. 4 ) resets the alarm on line  284  ( FIGS. 4 ,  8 ) in response to a key fob-transmitted remote signal if it goes high. Pin  8  (i.e., “D 3 ”) via line  150  ( FIGS. 4 ,  6 ) turns the green indicator status light  37  ( FIGS. 1 ,  2 ) “on” during the idle mode. Pin  9  (i.e., D 4 ) outputs on line  170  ( FIGS. 4 ,  6 ) to activate the red status light  38  ( FIGS. 1 ,  2 ) during the “armed” mode. 
   The transmitter module  114  ( FIG. 5 ) responds to a signal on line  119  ( FIGS. 5 ,  9 ) from pin  3  of timer  239  ( FIG. 9 ) described hereinafter. The signal on line  119  reaches transistor  121  through resistor  123 , energizing coil  111  of relay  125 . Relay contact  3  connects with terminal  127  ( FIG. 5 ). Relay contacts  5  and  6  interconnect an R/C timing circuit formed by resistor  128  and capacitor  130 , that connect at node, pin  6  leading to pin  6  of transmitter IC  131 . Resistor  133  discharges capacitor  130 . Preferably the programmable transmitter IC  131  comprises a Linx Technologies model TXE-315. Sensors  32 ,  34 , and  35  ( FIG. 1 ) are respectively connected to pins  2 ,  3 , and  7  of IC  131  via connector  214  ( FIG. 7 ) via lines  210 ,  211 ,  212  connected to lines  135 ,  134 , and  132  respectively that connect to pins  7 ,  3 , and  2  respectively of transmitter IC  131  ( FIG. 5 ). DIP switch  136  connects to pins  13 – 22  of transmitter IC  131  for unique addressing. These settings must be different from the receiver settings established by DIP switch  122  ( FIG. 4 ). DIP switch  138  connected to pins  8 – 12  of IC  131  ( FIG. 5 ) encodes data from IC  131  to identify a particular alarm unit. In this manner multiple alarm units may be used within a given location; the attendant for example, can determine which unit within a group of units at a particular installation was vandalized. 
   With joint reference now directed to  FIGS. 6–9  (which should be arranged for viewing as in  FIG. 10 ), the alarm activation circuit has been generally designated by the reference numeral  149 . The receiver IC  120  ( FIG. 4 ) outputs to a key fob demodulator, generally designated by the reference numeral  155  ( FIGS. 2 ,  6 ). Receiver control from pin  8  of IC  120  ( FIG. 4 ) is applied to line  150  and resistor  152  across capacitor  154  to pin  2  of NOR gate  156  ( FIG. 6 ). Gate  156  outputs to NAND gate  157  via line  158 . Gate  157  drives NAND gate  161  ( FIG. 8 ) via line  160 . Gate  161  outputs on line  162  to NAND gate  163  that activates transistor  165 . The green status light  37  (i.e., actually an LED) discussed previously is activated when transistor  165  turns “on.” As seen at the upper right of  FIG. 8 , the LED anode is connected via resistor  167  and connector  168  to +5 volts; the cathode end is in effect grounded by transistor  165 . When green status light  37  is illuminated it means that the alarm is disarmed. 
   Receiver IC  120  ( FIG. 4 ) also activates the red status indicator or LED  38  ( FIG. 8 ) to show that the alarm is “armed.” Pin  9  of receiver IC  120  ( FIG. 4 ) outputs to line  170  ( FIGS. 5   4 ,  6 ) through capacitor  172  and resistor  174  to activate NOR gate  177  that is coupled to NAND gate  178 . The output of NAND gate  178  on line  179  reaches pin  2  of NAND gate  157  through resistor  180 , causing a chain reaction through NAND gates  161 ,  163  and transistor  165  to turn off green LED  37 . 
   Line  179  ( FIG. 6 ) also connects to pin  13  of AND gate  182  and pin  5  of AND gate  184  via line  185 . Gate  182  outputs on line  186  that is applied to an “armed mode” timer  188  ( FIG. 8 ). Pin  9  of timer  188  outputs on line  190  to NOR gate  192  that outputs on line  193  and reaches inverter  194  ( FIG. 8 ). Driver transistor  196 , which is controlled by inverter  194 , activates the red LED status indicator  38  via line  197  and connector  168 . Flashing of the red LED  38  as per Table 1, above, results from control exercised by timer  188 . However, when the alarm is triggered, during, for example, a burglary, both indicator lights or LED&#39;s  37  and  38  are quickly flashed. Pin  5  of timer  200  ( FIG. 7 ), that is similar to timer  188 , outputs on line  202  ( FIGS. 7 ,  8 ) and reaches pin  12  of NOR gate  192  ( FIG. 8 ). Timers  188  and  200  result from a dual LM556 timer. Timer  188  ( FIG. 8 ) is the “armed mode” timer and timer  200  ( FIG. 7 ) is the “detected mode” timer. 
   NOR gate  192  ( FIG. 8 ) outputs on line  193  which reaches pin  1  of NAND gate  204  which outputs in the detected mode only on line  205  to reach pin  13  of NAND gate  163 . As previously explained, gate  163  controls driver transistor  165  that activates green indicator LED  37 . As a result, the green status light ( FIGS. 1 ,  8 ) is flashed at the opposite phase of the red LED to provide a dramatic visual intrusion warning. 
   Various “zones” or portions of a vending machine may be monitored by the alarm. These have been generically designated as “zone  1 ”, “zone  2 ,” and “zone  3 ” in  FIG. 2 , corresponding in the best mode to door sensors  34 ,  35  ( FIG. 1 ), and vibration sensor  32 . It should be apparent that other types of sensors may be used in substitution for the latter specific sensors. Signals from normally-open sensors  35 ,  34  and  32  (i.e., or zones  1 – 3  respectively) are inputted to the alarm&#39;s first false alarm protection circuit  213  ( FIGS. 7 ,  9 ) via lines  210 ,  211 , and  212  emanating from connector  214  (i.e., as seen in the lower left portion of  FIG. 7 ). Lines  210 – 212  respectively lead to inverters  218 ,  219  and  222  that output to AND gates  224  ( FIG. 7) and 226  ( FIG. 9 ). Inverters  218 ,  219  and  222  establish negative logic; all inputs and outputs of AND gates  224  and  226  are normally high. Gate  224 &#39;s output goes low when either a responsive zone  1  or zone  2  signal is present on one or both of its inputs, which occurs when the monitored sensors  35  and/or  34  “open.” Either the output of AND gate  224  on line  225  or a signal from zone  3  inverter  222  on line  227  must drop (i.e., go low) for AND gate  226  to go low on lines  229 ,  230  ( FIG. 9 ). If any sensor opens, OR gate  234  activates a one-shot multi-vibrator  236  ( FIG. 9 ) through R/C network  235 , inverter  237 , and R/C network  238 . Multivibrator  236  functions as a trigger; it operates timer  239  by outputting a negative-going pulse to timer pin  2  via resistor  240  and lines  241  and  242  ( FIG. 9 ). NAND gate  303  provides an alarm trigger pulse on lined  241  and  242  ( FIGS. 9 ,  11 ). In  FIG. 9  the pulse is represented at test line  305 . 
   Timer  239  ( FIG. 9 ) establishes a 3.5 to 4.5 minute timing interval during the detected or alarm mode. Timer  239  outputs on line  119  via node  244  to activate transmitter  114  ( FIG. 5 ) discussed earlier. Timer  239  also outputs on node  244  and line  246  ( FIGS. 7 ,  9 ), through resistor  248  to activate a solid state switch  249  (i.e., preferably a transistor, seen at the left  FIG. 7 ) which in turn outputs on line  252  through connector  253  to activate audio transducer  254  ( FIG. 7 ), which is preferably a 100 db siren. This siren can only activate when relay contacts  256  (i.e., a first audible alarm control means) and transistor switch  249  (i.e., a second audible alarm control means) are appropriately activated. 
   Power is applied to the transducer from power line  46  ( FIGS. 3 ,  7 ) via relay contacts  256  and line  257  ( FIG. 7 ). Relay coil  258  is directly switched on by any one of a trio  215  ( FIG. 7 ) of transistors that respectively connect to lines  210 ,  211 , and  212  via lines  216 ,  217 , and  221 . Resistors  209  forward bias transistors  215  ( FIG. 7 ) unless shorted by zone lines  210 ,  211 , or  212 . Transistor  203  latches the relay coil  258 . Transistors  215  prepare the alarm transducer  254  for firing by activating relay coil  258  to close contacts  256  whether the alarm is armed or not. However, the intelligent false alarm protection circuit  213  ultimately makes the decision to sound an alarm by controlling transistor  249  ( FIG. 7 ). For the alarm to sound, two events must occur simultaneously; i.e., power must be applied on line  257  (from contacts  256 ), and a control signal must appear on line  246  ( FIGS. 7 ,  9 ) to activate transistor  249 . This preferred arrangement makes it more difficult for a false alarm to occur in response to a line voltage transient, a power surge or the like. 
   Timer  239  ( FIG. 9 ) also activates multivibrator  260  that is formed by NAND gates  261 ,  262  ( FIG. 9 ), and which drives inverter  265  to output on line  266  ( FIGS. 6 ,  8 ,  9 ). Inverter  265  drives inverter  270  to output on line  272 . Lines  266  and  272  deliver signals identified respectively as “Control  1 ” and “Control  2 ” in  FIG. 11  which are 180 degrees out of phase. Line  266  leads to gate  161  ( FIG. 8 ), and it connects via line  267  ( FIGS. 6 ,  8 ) to AND gate  182  ( FIG. 6 ) previously discussed. Gate  182  controls timer  188  via line  186  ( FIGS. 6 ,  8 ). The CONTROL 2  signal from inverter  270  is applied via line  272  ( FIGS. 6 ,  8 ,  9 ) to NOR gate  177  ( FIG. 6 ), AND gate  184  ( FIG. 6 ), and NAND gate  204  ( FIG. 8 ). Gate  184  outputs on line  276  ( FIG. 6 ,  7 ) to turn timer  200  ( FIG. 7 ) “on.” Timer  200  connects to NOR gate  192  via line  202  ( FIGS. 7 ,  8 ) which outputs on line  193  connected to circuitry discussed previously that controls RED display LED  38  discussed previously. This results in rapid blinking of the RED LED when an intrusion is detected. At this same time, since NAND gate  204  ( FIG. 8 ) also responds to line  272 , it forces green LED display indicator  37  to rapidly switch on and off, via line  205  that goes to gate  163  previously described. 
   Line  272  ( FIGS. 8 ,  9 ) is connected to line  274  ( FIGS. 8 ,  9 ) that connects to one side of a NAND gate  275  that outputs to NAND gate  277 . The other input to gate  275  occurs via line  279 , that leads to a reset circuit  281  activated by hardware reset switch  283  ( FIG. 8 ) that is mechanically located within the interior  16  of cabinet  11  ( FIG. 1 ). The low output of gate  277  appearing on line  289  ( FIG. 9 ) resets timer  239  on pin  4  and multivibrator NAND gate  262 . 
   The purpose of reset circuit  281  ( FIG. 8 ) is to switch the alarm from the detected mode to the idle mode. Reset can be accomplished with hardware switch  283  ( FIG. 8 ), preferably hidden within the cabinet  11 , or with a remote control key fob  21  ( FIG. 2 ). Line  291  ( FIGS. 2 ,  6 ,  8 ) goes high from reset circuit  285  ( FIG. 8 ) and resets key fob demodulator  155 . The remote key fob operates receiver  112  ( FIG. 4 ) causing receiver IC  120  to output on pin  3  via line  284  ( FIGS. 4 ,  8 ) that activates reset circuit  281  ( FIG. 8 ) without any delay, to return to the idle mode. The hardware reset switch  283  ( FIG. 8 ) is hidden within the cabinet  11 . If per chance a thief knows of its location within cabinet interior  16  ( FIG. 1 ), a delay circuit  285  ( FIG. 8 ) prevents the alarm from immediately switching back to idle mode by delaying reset circuit  281  ( FIG. 8 ). Delay circuit  285  ( FIG. 8 ) does not respond to remote “reset” signals on line  284  from receiver IC  120  ( FIG. 4 ) that are transmitted remotely by the key fob  21  ( FIG. 2 ). 
   To prevent initial arming of the alarm (and/or to prevent the warning buzzer from sounding) during service and maintence, a trio of zone-monitoring diodes  280  ( FIG. 7 ) are employed to disable NOR gate  177  ( FIG. 6 ) via line  282  ( FIGS. 6 ,  7 ). 
   As mentioned above, the prevention circuit  213  ( FIG. 9 ) has been designed to minimize false alarms. Attention is directed to the top of  FIG. 9 , wherein a second false alarm prevention circuit  291  is shown. Protective diodes  292  and  294  have cathodes connected to timer  239  to prevent it from responding to voltage transients. The anode of protective diode  292  is connected via lines  229  and  230  to OR gate  234 . The anode of protective diode  294  is connected via line  295  to the output of NAND gate  296  ( FIG. 9 ). One input of NAND gate  296  leads via line  298  to a wave shaping circuit  299  comprising a diode and a pair of resistors. The other input to NAND gate  296  is connected via line  179  to inverter  300  and NOR gate  234  ( FIG. 9 ). The output from NAND gate  178  ( FIG. 6 ) is also received via line  179  and delivered to inverter  300 . Pin  2  (i.e., line  242 ) of timer  239  must go negative to set off the alarm, which is accomplished by the output of trigger  236  ( FIG. 9 ). However, protective diodes  292  and  294  must both be “off” for the timer  239  to be able to respond to multivibrator  236 . The “off” condition can take place for approximately 20 milliseconds only in the “armed” mode when any zone is being disturbed, as detected by sensors  32 ,  34  and/or  35 . 
   Timing 
   Turning to  FIG. 11 , preferred timing considerations have been graphically depicted by the chart  340 . There are three separate alarm states or operating conditions, comprising an “Idle Mode” represented by graph segment  342 , an “Armed Mode” designated by segment  343 , and a “Detected Mode” whose timing conditions are seen in segment  344 . 
   In the idle mode, machine service and maintence is enabled. Lines  211 ,  212 , and  210  ( FIGS. 6 ,  7 ,  11 ) connecting to the various door and vibration sensors can be opened or closed as indicated by trace  345 . Multivibrator  236  ( FIG. 9 ) will be low at this time as seen by trace  346 , and the trigger pulse on line  305  ( FIG. 9 ) is represented by graphical segment  348 . Voltage at the anodes of protective diodes  292  and  294  ( FIG. 9 ) in the second false alarm prevention circuit will vary as seen by segments  350 ,  352 . The CONTROL 1  signal on line  266  ( FIGS. 8 ,  9 ) is designated by reference numeral  354  in the idle mode; the CONTROL 2  signal on line  272  ( FIGS. 8 ,  9 ) designated by reference numeral  355  is generally 180 degrees out of phase. Reset lines  284  ( FIG. 8) and 279  ( FIG. 9 ) correspond generally to traces  356  and  357  ( FIG. 11 ). 
   In the armed mode indicated by segment  343  of  FIG. 11 , the alarm is “set” and it is watching for an intrusion. Lines  211 ,  212 , and  210  ( FIGS. 6 ,  7 ,  11 ) connecting to the various door and vibration sensors produce a quiescent signal as indicated by trace  360 . Multivibrator  236  ( FIG. 9 ) will be low at this time as seen by trace  362 , as will the trigger pulse on line  305  ( FIG. 9 ) as represented by graphical segment  364 . Voltage at the anodes of protective diodes  292  and  294  ( FIG. 9 ) in the second false alarm prevention circuit will be high and low as seen by graphical segments  366 ,  368 . The CONTROL 1  signal on line  266  ( FIGS. 8 ,  9 ) will continue high as designated by reference numeral  370 . The CONTROL 2  signal on line  272  ( FIGS. 8 ,  9 ) designated by reference numeral  372  continues to be 180 degrees out of phase. Reset lines  284  ( FIG. 8) and 279  ( FIGS. 8 ,  9 ) correspond generally to traces  374  and  376  ( FIG. 11 ). 
   A vertical dividing line  379  separates the armed mode from the detected mode; the graphical transitions between timing and the various signal states indicates an intrusion. In other words, the detected mode indicated by segment  344  of  FIG. 11  indicates that the alarm is responding to an intrusion. Lines  211 ,  212 , and  210  ( FIGS. 6 ,  7 ,  11 ) connecting to the various door and vibration sensors produce a warning signal indicated by trace  380 ; after timers function they may produce different signals  381 ,  382 . Multivibrator  236  ( FIG. 9 ) will exhibit trace  384 , and the trigger pulse on line  305  ( FIG. 9 ) is represented by segment  386 . Voltage at the anode of protective diode  292  ( FIG. 9 ) in the second false alarm prevention circuit will first be low as seen by graphical segments  388 , but at transition point  387  (i.e., when the door is closed after opening as illustrated by graphical segment  381  in  FIG. 11 ) the voltage rises as indicated by trace  389 . The voltage at the anode of protective diode  294  ( FIG. 9 ) in the second false alarm prevention circuit will be high as seen by trace  392 , and will drop as seen by trace  393 . The CONTROL 1  signal on line  266  ( FIGS. 8 ,  9 ) will drop as designated by signal trace  396 . The CONTROL 2  signal on line  272  ( FIGS. 8 ,  9 ) designated by reference numeral  398  goes high. Reset lines  284  ( FIG. 8) and 279  ( FIGS. 8 ,  9 ) correspond generally to traces  400 ,  402  ( FIG. 11 ). 
   The negative-going trigger pulse  305  ( FIG. 9 ) is represented by traces  348  and  364  in  FIG. 11 . However, means are provided to prevent a similar trigger pulse generated by noise, lighting or other bad line conditions from triggering the alarm. The false-alarm prevention diodes  292 ,  294  ( FIG. 9 ) prevent the alarm from firing if either one is forward biased. Noting traces  350 ,  352  ( FIG. 11 ) the alarm cannot go off. When for example, a door is opened, during the armed mode, indicated by vertical line  377 , time period T 1  begins, as indicated by arrows  406 . At this crucial time, indicated by graphical region  411 , both diodes  292 ,  294  are “low” as indicated by time period T 4  arrows  412 . For period T 4  indicated by arrows  412  ( FIG. 11 ) diodes  292  and  294  are both back-biased. Within period T 4  after delay T 1  pulse  305  occurs (line  386 ) during a period of time T 2  indicated by arrows  409 , to operate timer  239  ( FIG. 9 ). 
   Operation 
   The alarm can assume three operational modes, referred to as the “Idle,” “Armed,” and “Detected” modes. The idle mode is the default occurring automatically when power is applied and the apparatus is first energized. The idle mode is indicated by the green indicator LED  37  which is continuously “on.” Referring to  FIG. 12 , pressing the appropriate button  312  on key fob  21  initiates the “Armed mode” which is indicated by blinking of the red indicator LED  38 . Button  311  ( FIG. 12 ) establishes the idle mode. The armed mode is possible only when door is closed (i.e., the sensors  32 ,  34 ,  35  are not triggered). Remote key fob reset is achieved with button  313 . Orifice  309  is for miscellaneous car keys. An alarm switches state between the “armed mode” and the “detected mode” in response to triggering of any sensor  32 ,  34 ,  35 , as when the door opens or the unit is physically vibrated or pounded. 
   In the detected mode the buzzer  254  ( FIG. 7 ) goes on and both LEDs  37 ,  38  light. The buzzer sounds for approximately four minutes and then goes OFF. LEDs  37  and  38  continue to blink with disregard of the status of the doors (doors can be left open or closed). Any further intrusion causes the buzzer to again sound an alarm for four minutes. The only way to return the system to the default mode is to reset it. There are two ways to reset, either with the key fob  21  or the hidden reset switch  283  ( FIG. 8 ). 
   From the foregoing, it will be seen that this invention is one well adapted to obtain all the ends and objects herein set forth, together with other advantages which are inherent to the structure. 
   It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
   As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.