From: patenaude@nhtima.enet.dec.com (Roger Patenaude)
Newsgroups: rec.games.pinball
Subject: Re: What are Solid State Flippers
Date: 1 Oct 92 18:29:49 GMT
Article-I.D.: e2big.1992Oct1.182949.23689
Reply-To: patenaude@nhtima.enet.dec.com (Roger Patenaude)
Organization: Digital Equipment Corporation


Ok, I said I would.....



                               FLIPPER Theory
                             By Roger Patenaude


   Flippers are all basically the same, you energize a coil and it pulls in
   a plunger that is connected to a rod that flips a wedge shaped piece of
   plastic. But how this is implemented can be in a few different ways.
   I'll try to list in chronological order of appearance.



                           SERIES FLIPPER CIRCUIT

   This design has two coils wrapped around a single plunger, one large
   high power high current one to provide the initial bang and a smaller
   one to hold the plunger extended.


                     +VCC ---------/fs/-----+
                                            |
                                            +----+ 
                                            |    |
                                            _    |
                                            _    -
                                 large winding   eos
                                            _    _
                                            _    |
                                            |    |
                                            +----+
                                            |
                                            _
                                            _
                                 small winding
                                            _
                                            _
                                            |
                          +-----------------+
                          |
                        -----
                         ---  ground
                          -

   As you can see the two coils are wired in "series" with one another.
   When the flipper switch is closed the voltage (AC in older EMs and
   24-48VDC in newer machines) is applied to the coil. The coil is
   energized and pulls in the plunger who then pushes against the
   end-of-stroke switch. Once the switch is open we no longer have power
   through the big heat generating coil but we still do to the smaller
   coil so that we can hold the flipper switch without burning anything
   out. This setup is commonly used in the pre-early 80's machines.

   Some small add-ons you'll see to this on newer machine may be,,

   A) A diode across the windings, this stops a spike to be induced back
   into the logic when the coil is deenergized buy the collapsing
   magnetic field. (AKA: Ringing)

   B) A capacitor across the flipper switch, this reduces the arcing
   caused during the opening of the contacts.

   C) A capacitor across the EOS, same reason as above.



                          PARALLEL FLIPPER CIRCUIT

   For all intensive purposes this works the same as the series circuit
   except that the coils are now wired in parallel of each other. This
   means that we can use lower current to fire the coil and a higher
   voltage. Usually ~48VDC where series used lower voltage ~24VDC with
   more current. This is used in most of the games from about the early
   80's to the early 90's.


                     +VCC ---------/fs/-----+
                                            |
                                            +------+
                                            |      |
                                            -      |
                                           eos     |
                                            -      |
                                            |      |
                                            |      |
                                            _      -
                                            _      -
                                 large winding    small winding
                                            _      -
                                            _      -
                                            |      |
                                            +------+
                                            |
                                            |
                          +-----------------+
                          |
                        -----
                         ---  ground
                          -

   The problem with both the series and parallel designs are;

   A) Heat generated by the inner windings could not escape outward
   because of the insulation provided by the outer winding while the
   flipper was held. So the heat went inward instead. This causes the inner
   plastic sleeve the distort and bind the plunger, which caused more heat
   until it burnt out.

   B) Even though the flipper switch and EOS now have capacitors across
   them they still arc. This arcing causes impedance in the circuit hence
   lowering the available power to fire the coil. So with age you get
   weaker flippers. To fix this you have to constantly clean and rebuild
   them.

   C) EOS switches come out of adjustment or burn and in effect stop
   working. When this happens we don't de-energize the outer coil and
   although we get a strong flipper we also get a very short lived coil.

   D) The capacitors break off under the stress and we start to get
   weirdness in the game due to the spikes caused by the collapsing
   magnetic field makeing it back into the logic.

   E) Mechanical wearing out of the flipper parts.

   So DATA EAST came out with,,


                            SOLID STATE FLIPPERS

   Other wise known as a Daygar (SP?) design. In this circuit you use only
   one winding instead of two and two voltages instead of one.


                          PARALLEL FLIPPER CIRCUIT


                        +----------------+
                        |  +-----50vdc\  |
           +--/fs/---------|           >----+
           |            |  +-----8vdc-/  |  |
         -----          +----------------+  |
          --- ground                        |
           -                                |
                                            |
                                            |
                                            |
                                            _       
                                            _       
                                 large winding                 
                                            _       
                                            _       
                                            |       
                                            |          
                                          -----
                                           ---  ground
                                            -


   Now when you push the flipper button you fire both 50VDC and 8VDC at
   the coil. The 50V is on a one-shot so it times out rather quickly and
   the 8VDC is left as a hold voltage. 

   In this design you don't need a EOS (you enter you initials for high
   score with a dual set of flipper switch contacts), you don't generate
   as much if any heat because you are not wrapping one coil around the
   other, you don't arc you flipper switches because you are only
   grounding a low TTL (~3.5-4.5VDC) signal instead of 24VDC->110VAC.

   One major problem in the earlier solid state flipper implementations
   was that it was too good, too strong. Experienced players lost the
   "feel" of the flipper and often times the strength broke playfield
   parts. 

   DE used this design from about TIME MACHINE through PHANTOM Of The
   OPERA but now since the advent of TMNT they have slightly redesigned to
   a slightly weaker more controllable design. 

   Williams/BALLY have also started to use solid sate flipper designs.
   ADAMS FAMILY (T2 was still parallel) was the first. Because of the
   logic now employed in this design you also get the benefit of
   overriding the flipper switch input by OR'ing in an enable from logic
   (every wonder how THING flips in TAF??).

   I hope this little paper on flippers will help all you aficionados to
   under stand "how and why".

   Roger Patenaude


--
__

    |\/\/\/|                        Roger Patenaude
    |      |                        Pinball Pathologist
    |      |                        "Specializing in Autopsies of Dead Pins"
    | (.)(.)                       
    C      _)      /------------\  
    |  ,___|    ---| Don't Have |  
    |    /         | A Cow Man! |  
    /---\          \____________/