From Minecraft Wiki
Yes, 7 (when on)
Redstone torches can be used as crafting ingredients or redstone components.
 As a crafting ingredient
 As a redstone component
- See also: Redstone circuit
- To place a redstone torch, "use" it (right-click, by default) while aiming at the surface to which it should be attached.
- A redstone torch can be attached to:
- Redstone torches cannot be attached to the bottom of any blocks.
- Attempting to attach a redstone torch to an invalid surface can cause it to "snap" to a valid surface adjacent to the same space. For example, if a fence is on the ground, attempting to attach a redstone torch to the side of the fence will cause the redstone torch to be attached to the top of the ground next to the fence instead.
- See also: Torch placement
- A redstone torch is active unless the block it is attached to is powered. Effectively, a redstone torch inverts the signal applied to its attachment block: power level 0 is changed to 15 and power levels 1 to 15 are changed to 0 (for an alternative that produces a greater range of output power levels, consider a redstone comparator in subtraction mode).
- Walls, fences, glass, slabs, and stairs cannot be powered so redstone torches attached to them cannot be deactivated.
- A redstone torch takes 1 redstone tick (2 game ticks, or 0.1 seconds barring lag) to change state and won't change state unless the signal change to its attachment block is at least 1.5 redstone ticks long (unless the change is caused by the redstone torch itself in a "short-circuit"). For example, a redstone torch won't turn off if its attachment block receives a 1-tick or shorter pulse.
- While active, a redstone torch:
- produces "reddust" particles
powers any adjacent redstone dust to power level 15, including beneath the redstone torch if it is attached to the side of a block
powers any adjacent redstone comparators or redstone repeaters facing away from the redstone torch to power level 15
strongly powers any full solid opaque block above the redstone torch to power level 15 (but not next to or below it)
activates any adjacent mechanism components, including above or below, such as pistons, redstone lamps, etc.
- A redstone torch never affects the block it is attached to, even if it is a mechanism component. For example, a redstone torch attached to the top of a redstone lamp will not activate the lamp.
- A redstone torch will "burn-out" when it is forced to change state (by powering and de-powering the block it's attached to) more than eight times in 60 game ticks (three seconds, barring lag). After burning-out, a redstone torch will produce a "smoke" particle and a hiss similar to an extinguished fire, deactivate, and will then ignore attempts to change its state until the number of state changes in the last 60 game ticks drops to less than eight — after that it will re-activate when it receives a block update (an adjacent block changing its state or a redstone update which wouldn't normally de-activate the redstone torch) or a block tick (block ticks occur randomly, but on average affect a particular block once every 47 seconds). There is no limit on how often a single redstone torch can burn out.
- To remove a redstone torch, "attack" it (left-click, by default). Attacking a redstone torch takes no time and it will drop itself as an item.
- A redstone torch will also be removed and drop itself as an item:
- A redstone torch will be destroyed without dropping itself as an item if lava flows into its space.
|1.0.1||Added redstone torches.|
|1.1.0||Redstone torches can no longer be placed on tree leaves, but only in fancy mode.|
|1.0.2_01||Redstone torch, NOT gates, only signal into blocks above them or next to them.|
|1.2.0_02||Redstone torches no longer duplicate in SMP.|
|1.2_01||Fixed redstone torches acting really weird when placed.|
|1.6.6||It is now possible to place redstone torches on glowstone.|
|1.7.3||Corrected a redstone torch duplication bug when using pistons.|
|1.2||'Burnout' time reduced from 100 ticks to 60 ticks.|
|1.3.1||Redstone torches can now be placed on upside-down slabs and stairs.|
|1.4.2||Redstone torches are destroyed when an anvil falls on them.|
|1.5||13w01a||Redstone torches are used to craft redstone comparators and activator rails.|
|1.8||14w07a||Redstone torches attached to the wall are now simply rotated versions of upright redstone torches, rather than having their own block model.|
|TU1||Added redstone torches.|
Issues relating to "Redstone Torch" are maintained on the issue tracker. Report issues there.