At jantarmantar.org we have been modeling the Jantar Mantar instruments since the project began in 2003. Several architecture students created models based on measurements from Virendra Sharma, drawings from G.R. Kaye and Andreas Volwahsen, and our own panoramic photographs. The renderings in these galleries were created by Bei Xu.
The Delhi observatory includes the Misra Yantra, one of the most popular and most often photographed instruments of all. The Misra Yantra is unique to the Delhi observatory, and was not built by Jai Singh, but was constructed after his death, by his son Madho Singh in the early 1750s. I have also included renderings of the Rama Yantra, a paired cylindrical instrument. One other example exists at the Jaipur observatory, but it is much smaller in size.
The Misra Yantra at the Jaipur Observatory. The Misra Yantra is a compound instrument including a Karka Rasi Valaya, Dakshinottara Bhitti, Laghu Samrat, Niyat Chakras, and inclined western quadrant.