Steve H created a set of five short videos about the Astrolabe last year. They are available on YouTube. This provides a short overview of the instrument. It explains its use, history and construction.
The second part covers some more detailed calculations.
The third part explores the use of an Ephemeris explaining, for example, how to work out the best time to look for Jupiter in the night sky.
The fourth part explores the long history of Astrolabes and related instruments. From the fourth century BC up to Albert Einstein.
The last part covers the theory behind Astrolabes and how you can make your own.