EXHIBIT 5.1


October 7, 2002

Ault Incorporated
7105 Northland Terrace
Minneapolis, Minnesota 55428-1028

         Re:  Registration Statement on Form S-3
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Ladies and Gentlemen:

         We have acted as counsel to Ault Incorporated (the "Company") in
preparation of the Registration Statement on Form S-3 to be filed by the Company
with the Securities and Exchange Commission on October 8, 2002 relating to an
offering of up to 600,000 shares of the Company's Common Stock, no par value per
share (the "Common Stock") issuable (a) upon conversion of 2,074 shares of
$1,000 face value Series B 7% Convertible Preferred Stock (the "Preferred
Stock") and (b) as stock dividends on the Preferred Stock in lieu of cash. The
please be advised that as counsel to the Company, upon examination of such
corporate documents and records as we have deemed necessary or advisable for the
purposes of this opinion, it is our opinion that:

         1. The Company has been duly incorporated and is validly existing as a
corporation in good standing under the laws of the State of Minnesota.

         2. The shares of Preferred Stock and the issuance thereof have been
duly authorized by the Company.

         3. The shares of Common Stock issuable upon conversion of the Preferred
Stock, when issued by the Company upon conversion of the Preferred Stock, will
be validly issued, fully paid and nonassessable.

         4. If and when issued by the Company, the shares of Common Stock
issuable as dividends on the Preferred Stock will be validly issued, fully paid
and nonassessable.

         We express no opinion as to the laws of any state or jurisdiction other
than Minnesota. We do not undertake to update or supplement this opinion letter
or the opinions expressed herein.

         We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement, and to the reference to our firm under the heading
"Legal Opinions" in the Prospectus comprising a part of the Registration
Statement.

                                                 Very truly yours,

                                                 /s/ LINDQUIST & VENNUM P.L.L.P.