This is a short article on how to get true stereo from your electronics.
In order for a sound to be stereo, it needs two discrete audio paths. Without two discrete channels of audio, your electronics will always be in mono, no matter where you pan them.
In practical application this means running both the left and right output from your synth/sampler instead of just one side. Plug those two channels in next to each other on the mixer and pan them hard left and right.
By simply adding another channel of audio for your electronics, you've increased the depth and realism of your production. Effects like tremolo, stereo delay, and pan automation should now be apparent.