PROMISSORY NOTE

$375,000.00                                                April 15, 1995
                                                           Concord, California


         FOR VALUE RECEIVED, the undersigned,  ARIZONA INSTRUMENT CORPORATION, a
Delaware  corporation (the  "Borrower"),  hereby promises to pay to the order of
CLASSIC SYNDICATE, INC., an Illinois corporation, its successors or assigns (the
"Lender"),  the  principal sum of Three Hundred  Seventy-Five  Thousand  Dollars
($375,000.00)  and all interest  accrued  thereon.  The Borrower hereby promises
that the funds loaned  hereunder  shall be used  exclusively  for the payment of
Borrower's April 30, 1995 installment obligation to Bridge Capital Investors II.

         Interest shall accrue from the effective date hereof on the outstanding
principal  balance until all of the  principal  and interest due hereunder  have
been paid.  Such interest shall be calculated at a rate of ten percent (10%) per
annum.  Should  such  amount of  interest  be deemed  to be  usurious  under any
applicable  laws,  rules or  regulations,  then the amount of  interest  charged
hereunder shall be adjusted to the highest rate which is not usurious.  Interest
shall be calculated on the basis of a 360-day year and a twelve 30-day months.

         Semiannual  payments shall be made on October 30, 1995, April 30, 1996,
and  October  30, 1996 each in an amount  equal to all of the  interest  accrued
through the due date of such payment.  All of the outstanding  principal and all
remaining  accrued and unpaid  interest is due and payable in full no later than
April 30,  1997.  Borrower  shall have the right to prepay at any time,  without
penalty,  all or any portion of the principal and/or accrued interest,  provided
that any partial  payments shall be deemed  applicable first to accrued interest
and then to the outstanding principal.

         If any  payments of principal or interest on this note shall become due
on a  Saturday,  Sunday  or a public  holiday  under  the  laws of the  State of
California,  such payment shall be made on the next succeeding  business day and
such  extension of time shall in such case be included in computing  interest in
connection with such payment.

         Payments of both principal and interest are to be made at such place as
the Lender shall designate to the Borrower, in lawful money of the United States
of America, in immediately available funds.

         This note is issued pursuant to, is entitled to the benefits of, and is
subject to the terms of, a  Subordinated  Loan  Agreement  dated as of April 14,
1996 by and between  Borrower and Lender (the  "Subordinated  Loan  Agreement"),
providing  for,  among  other  things,  the  acceleration  of  the  indebtedness
evidenced by this note upon the  happening of certain  events of default and the
subordination of this note to certain other indebtedness of Borrower.
<PAGE>
         This note shall be governed by and  construed  in  accordance  with the
laws of the State of California.

                                     ARIZONA INSTRUMENT CORPORATION


                                     -------------------------------------

                                     Name:________________________________
(Corporate Seal)                     Title:_________________________________


Attest:

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Name:___________________________
Title:____________________________