[meatmanek]

If you're looking for code on how to pulse-width modulate the spikes so that you can decrease the speed, it can be done. However, realize that the spikes are mechanical devices, and switching them on and off wears them down. Normally, this isn't a problem, but it will be if you're switching them on and off once every second. The solution for the problem is to go to a solid state system - the Victor.

Now, if you're trying to run it slowly sometimes and quickly other times, you'll want to go with a Victor.

If you're trying to run it more slowly all of the time, the best solution might just be to change the gear ratio so you have more torque.