minecraft-java-edition
When I watch that video on YouTube, it shows you how to make a rapid fire tnt cannon. I made it, but when I activate it, it just explodes and the water flow out! I did that in survival mode, so I lost all the stuff to build that cannon because it exploded. Heres the video: Rapid Fire TNT Cannon
Heres some pictures:
While Ronan's answer will probably suffice in this situation, it will not be completely accurate. If you want a device that will pulse exactly 10 times, you can create a sort of counter with pistons. Here's the basic design:
This device uses a set of pistons to pulse a set number of times, then stop. Here's what the piston device looks like:
The glass block does not conduct redstone power, so the repeater does not power "through" it. All the stone blocks do conduct power, though, so those will be powered by the repeater. The pistons are set up to cycle through the blocks once the system is started, and it will stay on until the glass block becomes active.
These are the device's input and output. The lever overrides the glass block and turns the device on. The redstone line on the left will then pulse exactly 10 times before stopping. Note that the device will not stop if the lever remains on, so it might be a good idea to hook up a pulse limiter/extender to the input to keep the machine from malfunctioning.
Additionally, the speed of the pulses are determined by the clock seen in the first picture. By changing how fast the clock moves, you can adjust how often the output pulses. Note that I used all 1-tick repeaters to keep the length of the tick at about 2 redstone ticks, not extended to 4. If you're making it run more slowly, though, that's not necessary.
First, build the base, add water:
Add a holder for the 'firework' tnt block one block above the center:
Wire it up. Two repeaters at full spacing will give a good delay:
Test at this point, make sure all the wires light up when you hit the button. If any fail to, you'll blow it all up. Next, load it!
5..4..3..2..1...
Best Answer
I just re-watched the video, and compared it to what you are showing us here. I think I may have figured it out.
The video instructs you to place the final 3 bits of redstone on the second set of dispensers while the clock is running. This creates a delay between the explosion of the projectile TNT, and the propellant TNT. If you already have redstone on top of the second set of dispensers when the clock starts, the projectile TNT will be dispensed at the same time as the propellant TNT, and go off at the same time as your propellant. That little delay is critical to ensure that your cannon doesn't blow up in place, and that your projectile will actually move forward.