Talk:Redstone Comparator

Uses
Zigzagar 20:29, 25 November 2012 (UTC) Let's think of some good uses and looks for this right below:
 * Weight-dependant minecart intersections would be cool. Servers could have a sign that says "for rail 1 take 1 stack of cobble" and so on. It could use the signal strength dependant on weight and the capacitors will use only the ones they detect to switch a curved rail. Funky3000 21:33, 25 November 2012 (UTC)

Another possible use for the capacitor block would be to create an actual capacitor, where the capacitor can be used in a comparator to compare the input current with the internal charge of the capacitor, allowing for more true technologies to be implemented. Additionally, again using a storage medium for current (e.g, a ring of repeaters connected by opaque blocks.), better counters could be constructed, where a single input will simply charge the apparatus, while a second input would cause overflow, and the output would carry to the next unit. I had an idea where similar structures could even be used to create complex RSNNs (Resonant Spiking Neural Networks). 11:14, 15 December 2012

Block Name
At this stage the name is not really official, but I'm curious why they are calling the block a Capacitor when its real world equivalent is clearly a Comparator (real world Caps are energy storage devices, not energy comparing devices) Antiroot 20:06, 8 December 2012 (UTC)

->EDIT: The real world equivalent is actually an Avalanche diode. 11:06 15 December 2012 (EST)

Really any diode is capable of only outputting a high value if it's breakdown voltage (reverse biased) or forward voltage drop (an ideal/perfect diode) is exceeded, however since this "capacitor" block would have a configurable threshold (which typical diodes do not) a comparator is still a close equivalent, the only thing that does not match a real world comparator is that it seems the threshold is not dependent on a second input signal. So in a sense it would act similar to a configurable avalanche or zener, but since repeaters are commonly known as diodes (in a one direction current flow sense) having two blocks colloquially known as diodes would be misleading. Not intending to disagree/argue, just fueling the discussion machine

Edit: Dinnerbone's latest post of a Comparator does in fact expect two inputs (similar to a real world comparator's + - pins) and it has two modes, an open-loop and a mode similar to an op amp's negative feedback mode (although it's not exactly the same) Antiroot 19:41, 27 December 2012 (UTC)


 * The Capacitor IS the Comparator https://twitter.com/Dinnerbone/status/284388625595125760 Too bad Trigger hurt already made a page at Comparator, or I would move this.  20:21, 27 December 2012 (UTC)


 * Moved. -- Orthotope 20:59, 27 December 2012 (UTC)

Redirect
This page is redirected from Capacitor, but Capacitor is used in the box at the bottom. Pokechu22 02:21, 11 December 2012 (UTC)


 * I'm not too concerned about this; we'll get all the links sorted out once we know the official name of the block. I think it's unlikely to be 'Capacitor Block', so any links changed to point directly here would have to be changed again later. -- Orthotope 10:12, 11 December 2012 (UTC)
 * It's not official name it's completely different block. Check this wikipedia:Comparator and this wikipedia:Capacitor.--Darkhammer 03:27, 28 December 2012 (UTC)


 * As of today, 'Comparator' is the official name of the 'Capacitor' mentioned at MineCon, regardless of their real world counterparts.  03:34, 28 December 2012 (UTC)

Name problem, yet again
According to what I know, this seemed more Zener diode than capacitor.

Zener diodes are special diodes designed to work reversed. They will "regulate" the voltage between the ends of the device to its breakdown voltage, if possible. Usually, one end of the diode is grounded and the other is used to obtain a steady reference voltage. This property of Zener diodes are widely used as a voltage reference in a lot of real-life electronics, mainly power regulators and adapters (Maybe you can find one in the power adapter for your computer, either standalone or built into a power regulator chip like 7805.)

Given that in Minecraft, the circuitry all automatically get grounded to a common place, the behavior of "capacitor" essentially reminds of a way to connect a Zener diode to a circuit.

180.160.173.240 11:25, 17 December 2012 (UTC)

The name will be what it will be. "Comparator" is a good, understandable name for the block and is a much better name than "capacitor." Keep in mind that Redstone is completely different from real electricity in that it doesn't have to make a true "circuit." Names cannot match real life components exactly. --96.237.54.85 02:34, 5 January 2013 (UTC)

Available Information
There are a few things we could figure out regarding the thing. We know how it looks, yet there's no picture of it. It's also a good guess doesn't have physics,(it's an "attached" block, they generally don't) is transparent,(it must be, it's non-full) has a a low luminance when it's active,(it's redstone) has a 0 blast resistance,(also since it's an "attached" block) does not require a tool to break,(it's redstone) isn't renewable,(it's still redstone) and can be stacked.(no reason why not) I'm not familiar whith the policy regarding speculation on this wiki, but I just had to point it out.Spykee 16:48, 28 December 2012 (UTC)


 * The policy is zero speculation. We gather info from official Mojang sources or gameplay from development and official releases. While some conclusions may seem obvious, like yours assuming it has the same block characteristics as a repeater, it is still speculation, and doesn't belong here.  19:04, 28 December 2012 (UTC)

Thanks, as I said, I wasn't familiar with the speculation policy. What about the picture then? Spykee 14:29, 3 January 2013 (UTC)

Comparator in the snapshot
Someone without an account here - the Comparator, in the snapshot, takes input from the left or right and back side of the block with the output at the front. For reference, the output is where the side with the torch by itself is. In my tests:
 * If the signal from the back is weak while the signal from the left is strong, the Comparator will not emit a signal.
 * If the signal from the back is strong while the signal from the left is weak, the Comparator will emit the stronger of the two signals.
 * If the signal from the back is strong while the signal at the left is equally as strong, the Comparator will emit a fresh pulse. 71.252.223.107 17:23, 3 January 2013 (UTC)

Right click
Right clicking on comparator turns on or off the 3rd torch. But I haven't found how it changes behavior of comparator. 93.73.186.104 21:50, 3 January 2013 (UTC)

I think the third torch only matters when the input is another comparator, like in the second image.

85.55.199.216 13:58, 4 January 2013 (UTC)

Similar to the Op-amp
It's just me or the comparator is very similar to a operational amplifier

85.55.199.216 13:54, 4 January 2013 (UTC)

As a replacement for a rapid pulsar
When a redstone comparator is placed to power a dispenser, then powered up, the comparator will act as a rapid pulsar. It will not blink, but still power the dispenser to shoot at a rate of 300 items per minute, (or 5 items per second) Which can be useful to making extremely compact machine guns. Also due to the comparator's rapid activation rate (1/2 tick) the machine gun can turn on in a moment's notice, useful for making traps. Note: The dispenser will run out of ammunition (If it is filled with 64 in all 9 slots) in two minutes. (This is without a hopper adding extra ammunition)

Tl;dr: {lever/power source} + Comparator + Dispenser filled with arrows/firecharges/snowballs/eggs/items = PEW PEW! (At a rate of 5 items per second) 72.213.204.32 23:17, 5 January 2013 (UTC)Ferrariic "TheArcticFalcon"

Defining "how full" for a comparator.
The table indicates that not only slots, but "half slots" are significant. But that raises a bunch of questions: --Mental Mouse 00:17, 7 January 2013 (UTC)
 * 1) Some items stack only to 16, and some are unstackable.  Do these count as full slots, and do, e.g., snowballs, register "half slots" at 8?
 * 2) What are the rounding rules?

Your first question: Yes if it only stacks to 16 it will count as a full slot. (As long as the capacity is reached, it will be accepted as a full slot) Your second question: Minecraft rounds down, for example; Filling a hopper with 2 64s and 1 32 (Which would be half it's capacity) should read out 7 1/2, but it reads out as 7 out of the total of 15. Proving that Minecraft rounds down. This allows you to completly fill your chests without them sending off a full signal with a couple blocks missing. 72.213.204.32 05:08, 7 January 2013 (UTC)Ferrariic

I suspect it tracks quantity as an int and truncates rather then rounds down, not a functional distinction, but a minor one. 8.36.16.208 20:48, 11 March 2013 (UTC)

Comparator no longer provides autoupdates
An administrator will need to update the wiki, it doesn't let me remove the section "As a block updater" under "uses".

Thanks! --97.65.109.74 20:03, 31 January 2013 (UTC)

Rapid Pulser?
I saw a suggestion here for a Rapid Pulser, but it doesn't work for me, so I looked for another way.

It just needs to be wired into a loop that starts at the output of the Comparator and ends at the secondary input at the side and the Comparator at subtraction mode.

I= Input/Power O= Output >= Comparator r= Redstone

I >rrr O  rr

The problem with this is that it has a minimum distance in Redstone Wires to work, depending on the length of the loop.

--WHarris012 02:40, 12 April 2013 (UTC)


 * It's only the dust on the side of the comparator that varies between "some signal" and "no signal" (no matter the loop length). A loop of N dust causes the signal to drop by N-1 by the time it gets back to the comparator (the first dust right out of the comparator doesn't cause any drop). Then the comparator subtracts I-(N-1) from I to output a signal of N-1 which is strong enough to power N-1 dust, but not the last Nth dust -- which allows the comparator to blink back up to full strength again and repeat the cycle.
 * If you want to get your signal from another part of the loop, just add enough dust to get the same distance traveled as to the side dust. &mdash;Munin295 &middot; Book and Quill.png Stone Pickaxe.png &middot; 03:26, 12 April 2013 (UTC)


 * Yeah, I know; it was kind of a suggestion, really, that is if nobody else has brought the exact same schematics up (I guess I should have brought that up before).. Then I found out that if used this way, it can be used as a stable rapid pulser (opposite of original pulsers, which required a repeater to refine the signal; it can be used directly but does not work with repeaters) that can be controlled with a lever/button in place of the torch. Useful if you want a controlled, short RP.
 * Also, when I needed a RP that alternates at regular intervals, I used two of the same schematic, attached a repeater to the receiving end of one and hooked them up to a single lever. Worked as expected. --WHarris012 02:26, 9 September 2013 (UTC)

Power listings
Might I suggest a table for power listings? Something like this: This could also allow lists in the format '#stacks+#items/64', '#stacks+#items/16', '#items/64'...

NickNackGus 22:25, 5 May 2013 (UTC)

Need Help
I read the article and watched the video but I still dont know what to do with it.MichaelMinecraft 18:19, 23 July 2013 (UTC)

Ignore block 150
User:Darmo117 recently edited the article to remove mentions of block 150 (the "powered_comparator" block which isn't actually used). I just want to say that I support this decision. Block 150 can not be obtained in survival, has no real purpose even in creative mode, etc. At best it might be a piece of trivia. Let's let this article be about the redstone comparator that actually has a use. &mdash;munin &middot;  &middot; 17:45, 21 July 2014 (UTC)

Slow detection on hopper carts
Can anyone confirm that a comparator takes longer to detect items in a hopper minecart than in a normal hopper?

I was trying to make a hidden hopper lock, basically using a sorting unit (a double hopper with 22 items design) and wedging a hopper minecart where the top item-filled hopper goes (the hopper minecraft because it works though a block on top).

The original design always stops at 22 items left in the hopper, but with a hopper cart, it seems to lag behind, leaving 21 or 20 items, requiring 2 or 3 items to trigger again. --Tlaloc Temporal (talk) 08:38, 30 August 2014 (UTC)

1.5 tick
I hav witnessed with my own eyes som1 run a less than 2 tick pulse through a comparator. go to play.xisumavoid.com, plot world, /p visit Dedekind if u dont believe me. I believe it was a 1.5 tick pulse


 * The wiki is about vanilla Minecraft and xisuma's server is modded so can't be used to "prove" something for the wiki. However, you are correct that vanilla comparators can handle 1.5-tick pulses. The article only says that comparators "usually" can't handle 1-tick changes -- so that you've seen 1.5-tick pulses through a comparator is not inconsistent with the article. If you can find a way to describe its behavior more precisely that would help the article. &mdash;munin &middot; Book and Quill.png Stone Pickaxe.png &middot; 16:36, 9 March 2016 (UTC)

Unopenable chests register as normal
The current article states that "if a chest cannot be opened, the comparator will emit zero". My test shows that this is not true. Is this a 1.13 change? 71.238.149.95 23:18, 28 November 2018 (UTC)

False Fact on Trivia
This trivia "Comparators has no bottom texture; they appear transparent when viewed below. I'm planning to remove the false trivia but I don't know how to remove the template. I've even used that fact on a fact generator concept. IllogicalMinelogic (talk) 00:55, 29 July 2020 (UTC)

Lectern Bedrock Edition
Since on Bedrock Edition, a lectern would open 2 pages at a time instead of 1, how is the page measured through a comparator? MinecraftNoobCity (talk) 05:01, 17 May 2023 (UTC)

Comparing signal strength
I don't understand how this formula makes sense: output = rear × [left ≤ rear AND right ≤ rear]. can someone explain this?


 * [left ≤ rear] = [1 if left ≤ rear, 0 if rear < left], vice versa for right side. [0 AND 0] = 0, [0 AND 1] = 0, [1 AND 1] = 1. When the left and right inputs are less than or equal to the rear input, the output is 1 × rear = rear, and otherwise it's 0 × rear = 0. Blue Banana whotookthisname (talk) 12:02, 19 July 2023 (UTC)