Contract

Exhibit 10.4

     FOURTH AMENDMENT (the “Amendment”) dated as of November 30, 2009 (the “Amendment Effective Date”) by and between ADVANCED PHOTONIX, INC., a Delaware corporation (the “Company”) and XXXXX X. XXXXXX, an individual (“Holder”), to that certain SECURED PROMISSORY NOTE (the “Note”) dated as of May 2, 2005, as amended by the Amendment dated May 1, 2008, the Second Amendment dated November 26, 2008 and the Third Amendment dated April 1, 2009.

     The Company and Holder have agreed to amend and modify the Note in accordance with the terms and conditions hereinafter set forth. Unless otherwise defined herein, capitalized terms shall have the respective meanings assigned to them in the Note.

NOW, THEREFORE, in consideration of the foregoing, the parties, intending to be legally bound, hereby agree to replace in its entirety Section 1 of the Note as follows:

(1) PAYMENT OF PRINCIPAL. The Principal shall be payable in annual installments of ONE HUNDRED SIXTY SIX THOUSAND SIX HUNDRED SIXTY SEVEN DOLLARS ($166,667) on the first anniversary of the Issuance Date, ONE HUNDRED EIGHTY THREE THOUSAND THREE HUNDRED THIRTY THREE DOLLARS ($183,333) on the second anniversary of the Issuance Date, ONE HUNDRED FIFTY THOUSAND DOLLARS ($150,000) on December 1, 2008, ONE HUNDRED FIFTY THOUSAND DOLLARS ($150,000) on December 1, 2010, and a final installment of THREE HUNDRED SIXTEEN THOUSAND EIGHT HUNDRED THIRTY THREE DOLLARS ($316,833) on March 1, 2011 (the “Maturity Date”).

Except to the extent amended hereby, the Note remains in full force and effect in accordance with its terms and the Interest Rate (as defined in the Note) will continue to be paid at the rate prescribed in Section 2 of the Note. The terms and conditions of this Amendment shall be construed together with the terms of the Note as a single agreement, provided that, to the extent any terms and conditions of the Amendment are inconsistent with the terms and conditions of the Note, the terms and conditions of this Amendment shall govern.

     IN WITNESS WHEREOF, this Amendment has been executed by the Parties as of the Amendment Effective Date.

	ADVANCED PHOTONIX, INC.
	By:	/s/	Xxxxxxx X. Xxxxx
			Xxxxxxx X. Xxxxx,
			Chief Executive Officer
		/s/	Xxxxx X. Xxxxxx
			XXXXX X. XXXXXX