Weighted Pressure Plate

A weighted pressure plate is a block that can be used to measure the number of entities on it.

There are two versions of the weighted pressure plate: the light weighted pressure plate (aka "gold plate": ) and the heavy weighted pressure plate (aka "iron plate": ). The only difference between the two are the number of entities required to produce specific signal strengths.

Obtaining
A weighted pressure plate can be using any pickaxe. If mined without a pickaxe, it will drop nothing.

A weighted pressure plate will also be removed and drop itself as an item:
 * if its attachment block is moved, removed, or destroyed
 * if a piston tries to push it or moves a block into its space

Usage
A weighted pressure plate can be used to measure the number of entities on it.


 * Placement


 * To place a weighted pressure plate, use the control while aiming at the face of a block adjacent to the destination space.


 * A weighted pressure plate can be attached to:
 * the top of any full solid opaque block (stone, dirt, blocks of gold, etc.), including full-block mechanism components (command blocks, dispensers, droppers, note blocks, and redstone lamps)
 * the top of a hopper, fence, nether brick fence, an upside-down slab, or upside-down stairs.


 * A weighted pressure plate cannot be attached to the side or bottom of any block, but attempting to make such an attachment may cause the plate to attach to the top of a block under the destination space. For example, if a fence is on the ground, attempting to attach a plate to the side of the fence will cause the plate to be attached to the top of the ground next to the fence instead.


 * Activation


 * A weighted pressure plate activates when an entity is on top of it (specifically, when the entity's collision mask intersects the bottom quarter-block of the weighted pressure plate's space, which may include entities flying close to the ground) and deactivates 5 redstone ticks (0.5 seconds, barring lag) after no entities are on top of it, with a minimum activation time of 10 redstone ticks (1.0 seconds, barring lag).


 * A minecart traveling on rails will activate a weighted pressure plate next to a diagonal track but not one next to a straight track.


 * Behavior


 * While active, a weighted pressure plate:
 * powers adjacent redstone dust, or adjacent redstone comparators facing away from the plate, to a power level proportional to the number of entities on the plate (see table, right)
 * strongly powers a full solid opaque block beneath the weighted pressure plate to a power level proportional to the number of entities on the plate (see table, right)
 * powers adjacent redstone repeaters facing away from the weighted pressure plate to power level 15
 * activates adjacent mechanism components, including above or below, such as pistons, redstone lamps, etc.


 * An item stack counts as a single entity, no matter how many items are in the stack. When multiple items of the same type fall on a weighted pressure plate, they may initially be separate item entities and the weighted pressure plate will count them separately, but if they then collapse into a single item stack entity the signal strength from the weighted pressure plate may go down.

Water and lava will flow around a weighted pressure plate without affecting it.

Weighted pressure plates are not solid (they are not a barrier to entity movement). A block under a weighted pressure plate can provide a solid surface underneath it (for mobs to walk across, items to fall on, etc.), but when a weighted pressure plate is placed on a block with a small collision mask, such as a fence or nether brick fence, it is possible for entities to move through the plate while still activating it (walking through it horizontally, or falling through it vertically). Thus, a weighted pressure plate on a fence can be used to detect entities without stopping them (more compactly than a tripwire circuit).

Weighted pressure plates are 0.0625 blocks high ($1/16$ of a block) when inactive and 0.03125 block high ($1/32$ of a block) when active, but because they are not solid they do not affect the position of entities "on top" of them (for example, a player on top of a weighted pressure plate is actually standing on the block beneath it).

Data values
A weighted pressure plate is defined by its ID and block data. A weighted pressure plate also has a block state which is expected to replace the functionality of block data in a future version.

ID
A weighted pressure plate's ID specifies what type of weighted pressure plate it is.

Block data
A weighted pressure plate's block data stores its power level:

Video
Note: This video was made before 1.7.2 and is outdated. In particular, you no longer need as many items for either plate.

Issues
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