Tech Circles

First off make a NEW layer for your circle(or circles) and select the circle marquee tool.

Draw a circle (click on the canvas with circle marquee tool and drag, hold shift to make perfect circle)

Now with the marquee still selected(in other words, dotted line around the circle still there), go to Edit> Stroke...
Choose a width and color of your choice. You can also change where the stroke will be placed(center, inside, outside).

Now press ctrl + d to deselect the circle. Now use the rectangle marquee tool to draw a rectangle across the circle. Hit the delete key, and deselect again.

Keep repeating the above steps (even the new layer step), and start cutting them out differently and use different stroke widths, and your creativity.