No. But you can look up trazlanders redstone activated spawner filter and you could spawn mobs were you want when you want and how you want.

But that doesn't use command blocks

If you don't want a constant stream of mobs, and you don't want players spawning more than they should, you need command blocks & the scoreboard.

Unless you put in the code 52 to get spawner

Now as most people have tried to explain, there is no specific command. Others have mentioned people using up all the spawn eggs in the dispensers. Here is the tutorial on how to spawn mobs, but only allow a player to spawn them once. It also includes basic instructions on how to enable them to spawn them again after a specific amount of time.

Sorry it took so long, but i had problems recording the video. Followed by problems uploading....

https://www.youtube.com/watch?v=4lKQ5cc1xu4

Hope you are able to use it

That is true, but there are ways to prolong over usage, like a series of hoppers and a chest full of eggs, or if you are on a server, maybe a plugin that makes dispenser inventories infinite

If you need mobs to spawn with redstone, can you use dispensers?

I don't believe so, but if you are interested in command blocks there are a lot of great tutorials for them on youtube and good info on minecraft wiki.

You can't spawn mobs with command blocks but you can edit mob spawners to do so. Check out SethBling's Youtube channel for videos and filters on how to do this. In particular the 'create spawners', 'change mob properties' 'change spawner properties' and 'create geared mobs' filters will help you edit and spawn mobs.

now unless someone makes a mod/plugin for that there is really no way to do this

Nope. You can not use command blocks on mobs.