A circuit i made using opamps and transistors causes lots of oscillations (parasitic maybe ?), a solution to that which i find very reasonable is to limit the bandwidth of my main driving opamp so any oscillations are attenuated/removed. .
Update : adding a 100uF cap between pin 14 and ground removed about 99% of the oscillations , but instead i got this voltage spike that occurs when i drive the motor with a square wave ( the spike appears with every falling edge)
As far as I understand the question, your problem is with your phase and gain margins of the Op-Amp. To solve this problem, you might have two options, first you can add a compensation capacitor at the output of the Op-Amp (between Node14 and ground). The cap would reduce Unity-Gain Bandwidth of your Op-Amp and hence corrects your phase margin. Second, you can reduce gain of feedback loop (the feedback here is the wire from emitter of Q1 to node 13). In order to reduce feedback loop you can simply use a resistive divider. These topics are addressed here: http://www.mit.edu/afs.new/athena/course/2/2.010/www_f00/psets/hw3_dir/tutor3_dir/tut3_g.html
You cannot change or "limit" the frequency response of the opamp unit - however, you can limit the bandwidth of the loop gain (which is responsible for oscillatory behaviour). This can be done, for example, with a R-C series combination BETWEEN both opamp inputs (nodes 12 and 13). This is a kind of "input frequency compensation". Without knowing the exact loop gain response, one could start with R=100...500 ohms and C=100nF.
