Currently, I'm limited to using at most 15 blocks of redstone. Is there a way to bypass this limit? I dont want to use Wireless redstone because I want to see what is connected to what. Would be nice if someone knows how to disable the limit without writing the whole redstone engine again!
There are a number of methods for extending a redstone signal:
Just plonk down repeaters. Each one gives you another 15 blocks, however, there is a 1-tick delay in the signal for each repeater you use, which can slow down large circuits.
This allows for instantaneous redstone transmission over long distances. There's a wiki page for it! It's a little complex, so here's video:
Should the video go down, a search for Instant Wire will turn up many more.
MineFactory Reloaded has redstone wiring that can extend for supposedly unlimited distance, preserving signal strength, using a network system.
In addition to the accepted answer, extremely long distance wires can be made with a rate of 1 redstone to one block by using redstone torches. Put a single block down in the path of the redstone wire and put a wire on top, making sure that it is exactly 15 blocks from the source or the last torch switch, and put a redstone torch on one of its sides. With an odd number of switches, you will end up with the state of the last redstone torch the same as the state of the first one, essentially transmitting the signal. I believe there is a single tick of delay between the block a redstone torch is on being powered and it actually turning off, so this does introduce some delay, but it is significantly less costly than the "instant" wire (which has the delay of the piston anyway).
Repeaters! If you put a repeater down the redstone circuit will flow for another 15 blocks. This will slow the circuits signal down to the other end, but its useful in times. The number of ticks you add to the repeater, the slower the signal will go through the trail. You can craft a repeater with 3 stone, 2 redstone torches and one redstone. Hope this was helpful :)