Aids needed:

Sun, Venus, telescope and clear sky (which looked a bit hazy in the morning)

The principe:

By measuring the moments of contact of Venus and Sun as exactly as possible we can get the Sun parallax and then we can calculate the value of the Astronomical Unit from it. The formulas are complicated, but our professor and the pages of the Project VT 2004 saved us from calculating them. Some of us measured the time and we got the resulting one by making an average from them.Here are our results:
T2: 7:38:07
T3:13:02:57
T4:13:22:05
From it we got



The Astronomical Unit (AU)

We were very successful, our tolerance is not worth mentioning (if you want to know it after all it is 0,019%).We measured such Astronomical unit that even Mr. Kepler wouldn't have a reason to be ashamed of it.

AU=149 626 416 km

But that's not all. We measured the Sun diameter/ AU ratio
Rs/1AU=?
Rs=165 mm
Rv=5 mm
165/1600=0,103125

and the angular diamter of Sun and Venus by its illusive movement.
The Earth 1* round /axis rotation is 360° in 24 hours => 1 sec correspond with 15"
tV=5,26s =>The Venus diameter = 78,9''
tS=125,64s =>The Sun diameter = 1884,6'', that's about a half degree

Note:

If you don't like our results, look at your own and examine whether you have not made a mistake!