John Daniel Brosnan, 71, who founded his own burglar and fire protection company in Washington and who was active in the affairs of Catholic University, died Dec. 26 at Georgetown University Hospital. He had emphysema.

Mr. Brosnan was born in Washington and graduated from St. John's High School and in 1930 from Catholic University's for the Westinghouse Corporation after college.

In the late 1930s, he started his own business. This became the Federal Engineering Co. The firm installed and operated burglar and fire alarm systems. About 1970, Mr. Brosnan sold it to Wells Fargo Alarm Services, but continued as manager until his retirement in the early 1970s.

Mr. Brosnan was a member of the Institute of Electrical and Electronics Engineers and the North Washington Lions Club.

At Catholic University, he was a member of the Vaeth Unit of the Catholic Student Mission Crusade, the university's Century Circle and its Senators Club and the Friends of the Library of Catholic University. He was a member of the Church of the Annunciation and was active in behalf of the United Cerebral Palsy Fund.

He also was a member of the Banshee and Saints and Sinners clubs.

Survivors include his wife, the former Rae Embrey, of Washington; a sister, Helen M. Brosnan of Washington, and a brother, Thomas, of Fayetteville, N.Y.

The family suggests that expressions of sympathy be in the form of contributions to the Young Artist Fund, c/o Drama Department, Catholic University, Washington, D.C., 20064, or to Co -- Hope, Keezletown, Va., 22832, a home for the physically handicapped.