How to set aperture with cheap extension tubes on the nikon d3100?

Is there a way to set aperture on the nikon d3100 when using cheap extension tubes? I have read that you can set aperture by holding down the depth of field preview button while attaching the extension tube, However the Nikon d3100 does not have a depth of field preview button. Is there any other way to set aperture with cheap extension tubes?

Added (1). By the way, I don't have manual aperture adjustment on my lens.

That will only work if you have a lens with an aperture ring. Your question contains very little information so I bet you're trying to work with the 18-55.In that case, no there's no option to set your aperture.

Cheapest solution is to buy a used Ai or Ai-s lens, anything from 50mm to about 135mm will do nicely.

My guess is no.

The only extension tubes that work with dSLR's and newer AF-S lenses have to be those specifically designed to connect the controls from the camera to the lens. These extension tubes will have electrical contacts on them

Going cheap has limited value in this new age of dSLR cameras

The problem. There's nothing from your camera to tell the lens to adjust the aperture.

The solution.
There's a way to trick your camera. It is inconvenient thought.
1. Mount your lens to the camera. Without tubes
2. Set your aperture
3. Hold down the depth of field preview button (dof preview). And unmount your lens.
4. Look at your lens. You should notice the aperture has shrunken.
5. Mount extention tubes and new lens. Go go go

You set the aperture on the lens - NOT THE EXTENSION TUBES