Abstract:
A battery holder containing positive temperature coefficient (PTC) resetable fuse to electronically limit the maximum current that can be drawn from circuits built using reusable electronic component housings. A power supply with similar housing to reusable battery holders, also designed to limit maximum current and perform electrically equivalent to two or more battery holders. A reusable electronic housing with means for attaching any two leaded electronic component for insertion into quick connect assembly system. This housing also contains a positive temperature coefficient (PTC) resetable fuse to electroniclly limit the maximum current that can be sent through the attached two leaded component.

Description:
FIELD OF THE INVENTION 
   This invention relates generally to devices used with circuits that easily and quickly connect together and specifically to circuits constructed by children or students. It insures that the circuit will be safe and is designed to prevent damage to components or any object or person in close proximity to these components. 
   BACKGROUND OF THE INVENTION 
   There are toys and teaching aids that use a mechanical connector to quickly assemble electronic circuits. Sooner or later these components are connected to a power source such as a battery. If the circuit allows too much current to flow, certain devices may become extremely hot and even explode. 
   Fuses may be connected in series with the power source that will open when excessive current flows. Since most inexpensive fuses must be replaced, this process is inconvenient and allows the child or student the option of using a conductor that eliminates the protection device. Mechanically resetable fuses are expensive and some can be held in the on position to eliminate the protection feature of the fuse. 
   Another safety problem exists when polarized capacitors are installed backwards in electronic circuits. The capacitors leakage current will increase significantly and the device will rise in temperature and may even explode. Many existing products do not consider the safety of the child or student when allowing for the insertion of capacitors and other “off the shelf” electronic components. 
   SUMMARY OF THE INVENTION 
   Quick connect assembly systems currently being sold consist of a box of electronic devices mounted to quick connect bases. Diagrams for hundreds of circuits are included to educate a student or entertain a child. When these circuits are assembled the child can listen to a radio station, send a flying saucer on mission, create and store sounds . . . just to name a few. Sooner or later the child or student will either connect a component incorrectly or decide to experiment with the connections. 
   Whenever new circuits are constructed the potential for damage to the parts will occur and safety problems will arise. 
   To take care of excessive current and circuit shorts, a specially designed battery holder and AC/DC interface containing a PTC resetable fuse has been invented. A positive temperature coefficient (PTC) resetable fuse electronically limits the maximum current and automatically resets when the problem is removed. This device can be inside the module and not available to the child or student for maximum amount of protection. When the battery holder provides the input power, the PTC resetable fuse is in series with the positive terminal. Even if the external power supply with quick connect circuit type connector is used, the student or child is protected since it also has the PTC resetable fuse in series with the positive terminal. 
   This PTC fuse will rise in resistance value and limit the amount of current flowing whenever it is raised in temperature. By placing it in series with electronic components, it will limit both AC and DC currents to a safe level if the parts are used incorrectly. As current increases the temperature of the PTC also increases. This raises the resistance of the PTC which lowers the voltage and prevents damage to the electronic components. As soon as the electrical current level is restored to a safe level, the temperature of the PTC will drop allowing circuits to receive the proper voltage. Placing the PTC inside the battery holder or inside the quick connect circuit AC/DC power plug, prevents the user from touching it when it is at an elevated temperature. The use of non-polarized capacitors will help take care of incorrect DC connection of capacitors but will not cure the problem of extremely high AC currents through capacitors that can also cause heating and explosion. By placing PTC resetable fuses, that cannot be removed by the child or student, in series with sensitive electronic components of all these problems can be eliminated. Adding the PTC resetable fuse in series with any “off the shelf” component will likewise prevent excessive current from flowing. Any module that accepts non-polarized capacitors or “off the shelf” components should have this type of protection. 

   
     BRIEF DESCRIPTION OF FIGURES 
     The accompanying Figures illustrate the following: 
       FIG. 1  shows a drawing of a wall type power source  100  that provides stackable DC voltage outputs  107 ,  108 ,  109 ,  110 . The special modules  101 ,  102  on the ends of each output cord  111 ,  112  are designed to be unique and interface only with snap circuit devices. Each module  101 ,  102  containing a PTC resetable fuse  103 ,  104  respectively, wired in series with the plus terminals  107 ,  108  for safety protection. Each module  101 ,  102  has a plus  107 ,  108  and a minus  109 ,  110  DC voltage output terminal. 
       FIG. 2  is a schematic of an electronic circuit used to make the DC outputs  107 ,  108 ,  109 ,  110  of an AC to DC power source stackable (no common ground). 
       FIG. 3  is a schematic of typical regulating circuit placed in each of the DC output pairs  107 ,  109  and  108 ,  110 . This circuit provides current limiting and heat protection. 
       FIG. 4  is a drawing of a quick connect circuit module that uses springs  402 ,  403  to connect any two leaded “off the shelf” component  401  in series with a PTC resetable fuse  404 . 
       FIG. 5  is a drawing of a clear quick connect circuit Base  500  that can be used to mount battery holder module  600 , and other quick connect  510  through  516  similar to the spring circuit module  400 . 
       FIG. 6  is a battery holder module  600  designed to hold two batteries  601 ,  602 . The battery has a positive terminal  603 , and a negative terminal  604 , that are designed to connect to existing snap circuit components. The positive terminal  603  is in series with a PTC resetable fuse  605  to limit the maximum current taken from the batteries  601 ,  602 . 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The present inventions consist of an improved battery holder module  600 , Positive Temperature Coefficient Automatically Resetable Fuses  103 ,  104 ,  404  and  605 , a specially designed power source  100  with unique stackable output plugs  101  and  102 , a quick connect module  400  for electronic components, a clear see through plastic base  500  with mechanical compatible connectors for quick connect circuit interfacing some of which are shown as components  510 – 516 ,  600 . The battery holder module  600  is designed to be used as a direct replacement for existing quick connect circuit type battery holder modules. The clear plastic base  500  serves as a support to mount the quick connect circuit modules. 
   The quick connect circuit systems that are presently being sold use battery holders that can be placed in series to stack the voltages. The addition of the Positive Temperature Coefficient Automatically Resetable Fuse  605  prevents shorts from producing heat that can damage the battery holder and cause possible injury to the user. A custom wall adapter power source  100  with multiple outputs  101 ,  102  must also be stackable to interface properly with the battery powered quick connect circuit designs in use today. Each output plug  101 ,  102  is driven from an isolated secondary transformer coil  204 ,  205  and uses a separate regulating circuit  207 ,  208  respectively. There may be any number of isolated outputs  101 ,  102  to allow for increased stacking capability. Each one of the regulated circuits  207 ,  208  contains current limiting features to further insure safety when shorts or bad wiring is present. The unique power connectors  101 ,  102  are designed to mate only with other snap circuit modules. The actual shape of the connectors  101 , and  102  is important because this unique design prevents the battery module  600  from being directly connected in parallel with the AC/DC power source connectors  101 ,  102 . This further increases safety by preventing a child or student from easily plugging a battery module  600  in parallel with a power source connector  101 ,  102 . 
   The regulating circuit shown in  FIG. 3  is powered by a transformer  200  with a single primary winding  210  and a multiplicity of secondary winding  204 ,  205 . Each secondary winding will need a separate regulating circuit  207 ,  208  to insure complete isolation. Each regulating circuit  207 ,  208  will contain an electronic circuit similar to the one shown in  FIG. 3 . 
   Figure shows the input to the DC Regulator as a secondary winding  300  on a transformer. This could be either of the two secondaries  204 ,  205  shown in  FIG. 2 . This secondary drive a diode bridge consisting of diodes  301 ,  302   303  and  304  and converts the AC input signal to a DC signal. Capacitor  305  is used to filter out AC ripple. The integrated circuit  306 , a type similar to the LM317, sets the output at 3 volts, provides regulation, and provides short circuit protection. Resistors  307  and  308  are necessary to set the output voltage at 3 volts. 
     FIG. 4  shows a module  400  that allows a student or child to insert a standard two lead component  401 . This module  400  provides a set of clips or springs  402 ,  403  that easily connect to standard electronic component leads  405 . This module  400  also has a Positive Temperature Coefficient Automatically Resetable Fuse  404  in series with one spring connection  403  and the quick connect circuit connection  406  to limit the maximum current that can pass through the connected electronic component  401 . The Positive Temperature Coefficient Automatically Resetable Fuse  404  also will limit the current if an AC or DC power source is connected to the springs  402 ,  403 . 
   All the modules use a base  500  similar to the one shown in  FIG. 5 . The plastic post  502  are spaced to accept the circuit connectors that exist on the quick connect circuit modules in use today. A child or student assembles the project by placing the lower layer of modules  600 ,  511 ,  513 ,  515  onto the plastic post  502  of the base  500  first. The second layer of modules  510 ,  516 ,  514 ,  512  are then added to complete the electrical circuit. Since the child or student has the capability of placing modules in any combination, the possibility of short circuits and excessive currents exist if some type of fuse in not in series with all power sources. 
   The quick connect module  400  of the quick connect circuit connection  406  may have a top side  420  and a bottom side  421 . The top side  420  of the quick connect module  400  may have a male member  422  and the bottom side  421  of the quick connect module  400  may have the female member  423 . The male member  422  may be connected to the female member  423  via a shaft  424 . Accordingly, the male member  422  of quick connect module  400  may not be inserted into the female member  423  of the same quick connect module  400 . Instead, the male member  422  of one quick connect module  400  may be inserted into the female member  423  of a different quick connect module  400  or other component. Further, both the male member  422  and the female member  423  may conduct electricity. 
   The male member  422  may be snap-fittingly coupled with a female member  423 . The male member  422  portion of the quick connect module  400  may have a circular plate-like base  430  and a plug  431  integral therewith. The plug  431  of the male member  422  has an outwardly directed semi-circular locking projection  433  engageable with rods  452  of the female member  423  (as is described below). 
   The female member  423  portion of the quick connect module  400  may have a circular plate-like base  450  and a cylindrical socket  451  disposed on the underside of and integral with the base  450 . The base  450  may have a central bore  453  for receiving the male member  422 . Located within the central bore  453  may be two rods  452 . The rods  452  may be substantially parallel with the bottom side  421  of the quick connect module  400 . A cavity  425  may be located above the rods  452  and within the central bore  453 . A spring may be located within the female member  423  portion whereby the spring provides pressure which forces the rods  452  toward the center of the central bore  453 . While the male member  422  is inserted into the central bore  453  of the female member  423 , the outwardly directed semi-circular locking projection  433  of the male member  422  may contact the rods  452  and force the rods  452  away from the center of the central bore  453 . 
   When the outwardly directed semi-circular locking projection  433  portion of the male member  422  has been fully inserted into the female member  423 , the outwardly directed semi-circular locking projection  433  may reside within the cavity  425  of the female member  423  and the springs may force the rods  452  inward toward the center of the central bore  453 . In this position the male member  422  is removably secured within the female member  423  by the rods  452  which are secured by the springs. The male member  422  may be removed from the female member  423  by applying force to overcome the tension created by the springs in holding the rods  452  under the outwardly directed semi-circular locking projection  433 . 
   Accordingly, although the invention has been described by reference to a preferred embodiment, it is not intended that the novel assembly be limited thereby, but that modifications thereof are intended to be included as falling within the broad scope and spirit of the foregoing disclosure, the following claims and the appended drawings.