The LiD [Liquid in Dispenser] T-flipflop first came to my attention as part of a door design by Nitrox Nova (qqv. Easy Iron Doors in All of My Redstone Inventions & the associated video Minecraft Compact Iron Door With Buttons! (No Pressure Plates) )

As no version of this T-flipflop appears in https://minecraft.gamepedia.com/Memory_circuit#T_flip-flop , it is believed to be novel.

The functioning of this circuit is based on three behaviors:

• that a dispenser containing a full bucket (water or lava) will alternately place and retrieve the liquid as the dispenser is repeatedly activated,
• that a comparator 'reading' a dispenser will have an output of two (2) when the contents are a single non-stackable item and an output of one (1) when the contents are a single stackable item,
• a full bucket is non-stackable, an empty bucket stackable (to 16).

The basic form of the LiD T-flipflop is shown here:

With the liquid in the dispenser [above], the full bucket gives a comparator output of two (2)... just sufficient to power the repeater or turn off the RS-torch on the pink wool.
With the liquid dispensed [below], the empty bucket gives a comparator output of one (1), which powers only the redstone dust [RSD] on the white wool.
(In each example, any – or all – of the red glass may be removed if one is unconcerned with the water flowing. )

The example used in the above referenced door build makes use of a further mechanic to slightly compress the output side of the flipflop; the principle is illustrated by the following example.


In this instance the comparator 'reading' the dispenser [the upper comparator, pointing to the left] is set to subtract mode, and a reference signal of strength one (1) provided by a second comparator 'reading' a container.

As seen in this overhead:
the function is otherwise identical to the version first shown. [Note that the input and water chamber in the above example have been relocated from the door build for greater clarity.]

Any container may be used to provide the reference signal with furnaces [8 cobble] and half chests [8 planks] the least expensive options. Any single stackable item will generate the required signal strength of one (1)
[A few blocks such as cakes and cauldrons are other options: qv. https://minecraft.gamepedia.com/Redstone_Comparator#Measure_block_state (particularly the chart "Minimum Items for Container Signal Strength ") for a full guide.]


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