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                                  UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13D/A
                    Under the Securities Exchange Act of 1934
                                (Amendment No. 1)

                       ELECTRONIC SENSOR TECHNOLOGY, INC.
                       ----------------------------------
                                (Name of Issuer)

                    Common Stock, par value $0.001 per share
                    ----------------------------------------
                         (Title of Class of Securities)

                                    285835104
                                 --------------
                                 (CUSIP Number)

                                   Philip Yee
                Secretary, Treasurer and Chief Financial Officer
                       Electronic Sensor Technology, Inc.
                           1077 Business Center Circle
                         Newbury Park, California 91320
                                 (805) 480-1994
                -------------------------------------------------
                  (Name, Address and Telephone Number of Person
                Authorized to Receive Notices and Communications)

                                 With a copy to:

                               Neil W. Rust, Esq.
                                White & Case LLP
                        633 West Fifth Street, Suite 1900
                          Los Angeles, California 90071
                                 (213) 620-7700

                                 March 28, 2008
             -------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition that is the subject of this Schedule 13D, and is filing this
schedule because of Sections 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check
the following box [ ].

The remainder of this cover page shall be filled out for reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).

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CUSIP NO. 285835104

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1      NAME OF REPORTING PERSON                                   3 Springs, LLC

       I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

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2      CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP                   (a)[X]
                                                                          (b)[ ]

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3      SEC USE ONLY

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4      SOURCE OF FUNDS                                                        OO

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5      CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS
       IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e)                            [ ]

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6      CITIZENSHIP OR PLACE OF ORGANIZATION                             Delaware

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        NUMBER OF        7      SOLE VOTING POWER                              0
          SHARES
       BENEFICIALLY      -------------------------------------------------------
        OWNED BY         8      SHARED VOTING POWER                3,853,160 (1)
           THE
        REPORTING        -------------------------------------------------------
       PERSON WITH       9      SOLE DISPOSITIVE POWER                         0

                         -------------------------------------------------------
                         10     SHARED DISPOSITIVE POWER           3,853,160 (1)

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11     AGGREGATE AMOUNT BENEFICIALLY OWNED BY THE
       REPORTING PERSON                                            3,853,160 (1)

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12     CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11)
       EXCLUDES CERTAIN SHARES                                               [ ]

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13     PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)              2.47% (2)

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14     TYPE OF REPORTING PERSON                                               OO

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(1)    Includes 3,595,913 shares of Electronic Sensor Technology, Inc.'s common
       stock, par value $0.001 per share (the "Common Stock") and 257,247 shares
       of Common Stock underlying warrants exercisable within 60 days of
       March 31, 2008.

(2)    This percentage is calculated based upon the total amount of outstanding
       shares of Common Stock beneficially owned by 3 Springs, LLC, including
       shares of Common Stock that 3 Springs, LLC has the right to acquire
       within 60 days pursuant to warrants, divided by 155,853,385, which
       represents the total number of shares of Common Stock issued and
       outstanding as of March 31, 2008, plus the shares of Common Stock that 3
       Springs, LLC has the right to acquire within 60 days pursuant to
       warrants.

CUSIP NO. 285835104

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1      NAME OF REPORTING PERSON                                    Francis Chang

       I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

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2      CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP                   (a)[X]
                                                                          (b)[ ]

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3      SEC USE ONLY

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4      SOURCE OF FUNDS                                                        OO

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5      CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS
       IS REQUIRED PURSUANT TO ITEM 2(d) or 2(e)                             [ ]

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6      CITIZENSHIP OR PLACE OF ORGANIZATION                        United States

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        NUMBER OF        7      SOLE VOTING POWER                    170,000 (1)
          SHARES
       BENEFICIALLY      -------------------------------------------------------
        OWNED BY         8      SHARED VOTING POWER                3,853,160 (2)
           THE
        REPORTING        -------------------------------------------------------
       PERSON WITH       9      SOLE DISPOSITIVE POWER               170,000 (1)

                         -------------------------------------------------------
                         10     SHARED DISPOSITIVE POWER           3,853,160 (2)

--------------------------------------------------------------------------------
11     AGGREGATE AMOUNT BENEFICIALLY OWNED BY THE
       REPORTING PERSON                                         4,023,160 (1)(2)

--------------------------------------------------------------------------------
12     CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11)
       EXCLUDES CERTAIN SHARES                                               [ ]

--------------------------------------------------------------------------------
13     PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)              2.57% (3)

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14     TYPE OF REPORTING PERSON                                               IN

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(1)    Includes 170,000 shares of Common Stock underlying an option owned by
       Francis Chang exercisable within 60 days of March 31, 2008.

(2)    Includes 3,595,913 shares of Common Stock and 257,247 shares of Common
       Stock underlying warrants exercisable within 60 days of March 31, 2008
       owned by 3 Springs, LLC and beneficially owned by Francis Chang by virtue
       of his position as sole member of 3 Springs, LLC.

(3)    This percentage is calculated based upon the total amount of outstanding
       shares of Common Stock beneficially owned by the Reporting Persons,
       including shares of Common Stock that the Reporting Persons have the
       right to acquire within 60 days pursuant to an option and warrants,
       divided by 155,853,385, which represents the total number of shares of
       Common Stock issued and outstanding as of March 31, 2008, plus the shares
       of Common Stock that the Reporting Persons have the right to acquire
       within 60 days pursuant to an option and warrants.

Item 1.  Security and Issuer

         This Schedule 13D relates to shares of common stock, par value $0.001
per share (the "Common Stock"), of Electronic Sensor Technology, Inc., a Nevada
corporation (the "Issuer"), held by the persons identified herein. The address
of the principal executive office of the Issuer is 1077 Business Center Circle,
Newbury Park, California 91320.

Item 2.  Identity and Background

         This Schedule 13D is filed jointly by Francis Chang, a United States
citizen, and 3 Springs, LLC, a Delaware limited liability company ("3 Springs";
Mr. Chang and 3 Springs are each sometimes referred to herein as "Reporting
Person" and are collectively referred to herein as the "Reporting Persons"). The
Reporting Persons are making this single, joint filing because they may be
deemed to constitute a "group" within the meaning of Section 13(d)(3) of the
Securities Exchange Act of 1934, as amended (the "Act"), with respect to the
transaction described in Item 3 of this Schedule 13D and thus are eligible to
make a joint filing under Rule 13d-1(k) promulgated under the Act. Attached
hereto as Exhibit 99.1, and incorporated herein by reference, is a Joint Filing
Agreement among Reporting Persons indicating that this statement is filed on
behalf of each of such Reporting Persons.

         Mr. Chang is retired and he currently serves as a director of the
Issuer. Mr. Chang has served as a director of the Issuer since January 31, 2005
and served as Secretary, Treasurer and Vice President of Finance and
Administration from February 1, 2005 through November 1, 2006. Mr. Chang was the
Vice President of Finance and Operations of Electronic Sensor Technology, L.P.
from March 1995 through February 2005. Mr. Chang does not serve as a director of
any other publicly reporting company.

         Mr. Chang is the sole member of 3 Springs. 3 Springs is an investment
holding company. The address of the principal business office of each of Mr.
Chang and 3 Springs is c/o Electronic Sensor Technology, Inc., 1077 Business
Center Circle, Newbury Park, California 91320.

         Neither of the Reporting Persons, nor to the best knowledge of the
Reporting Persons has, during the last five (5) years, been convicted in a
criminal proceeding (excluding traffic violations or similar misdemeanors) or
been a party to a civil proceeding of a judicial or administrative body of
competent jurisdiction resulting in a judgment, decree or final order enjoining
future violations of, or prohibiting or mandating activities subject to, Federal
or State securities laws or finding any violation with respect to such laws.

Item 3.  Source and Amount of Funds or Other Consideration

          This statement is being filed to report the fact that as of the date
hereof, due to dilution of the Common Stock beneficially owned by the Reporting
Persons as a result of the recent investment by Halfmoon Bay Capital Ltd, each
of the Reporting Persons has ceased to be a beneficial owner of more than 5%
of the Common Stock of the Issuer.

         The Issuer was incorporated under the laws of the state of Nevada as
Bluestone Ventures Inc. ("Bluestone") on July 12, 2000. The Issuer changed its
name to Electronic Sensor Technology, Inc. on January 26, 2005. The Reporting
Persons acquired their shares of Common Stock in connection with the acquisition
by merger of the parent companies of Electronic Sensor Technology, L.P. (the
acquisition, as more fully described below, referred to herein as the
"Transaction").

         On February 1, 2005, pursuant to the terms of an Agreement and Plan of
Merger by and among the Issuer, Amerasia Technology, Inc. ("Amerasia
Technology") holder of approximately 55% of the partnership interests of
Electronic Sensor Technology, L.P., L&G Sensor Technology, Inc. ("L&G Sensor
Technology") holder of approximately 45% of the partnership interests of
Electronic Sensor Technology, L.P., Amerasia Acquisition Corp., a wholly-owned
subsidiary of the Issuer, and L&G Acquisition Corp., a wholly-owned subsidiary
of the Issuer, the Issuer acquired 100% of the outstanding equity partnership
interests of Electronic Sensor Technology, L.P. Under the Agreement and Plan of
Merger:

   (i)   Amerasia Technology merged with and into Amerasia Acquisition Corp.
         such that it became a wholly-owned subsidiary of the Issuer;

                                        1

   (ii)  L&G Sensor Technology merged with and into L&G Acquisition Corp. such
         that L&G Sensor Technology became a wholly-owned subsidiary of the
         Issuer;

   (iii) as a result of the mergers of (i) and (ii), the Issuer indirectly
         acquired the partnership interests of Electronic Sensor Technology,
         L.P.; and

   (iv)  The Issuer issued 20,000,000 shares of its Common Stock to the
         shareholders of Amerasia Technology and L&G Sensor Technology.

         Prior to the Transaction, Mr. Chang owned 30.21% of the outstanding
shares of Amerasia Technology. Pursuant to the Agreement and Plan of Merger, Mr.
Chang had the right to receive 3,081,421 shares of Bluestone common stock in
exchange for his shares of Amerasia Technology, which he assigned to 3 Springs
and such shares were issued to 3 Springs in the Transaction.

         Prior to the Transaction, Electronic Sensor Technology, L.P. entered
into Debt Conversion Agreements with holders of its outstanding debt, including
Mr. Chang and Amerasia Technology. Pursuant to the Debt Conversion Agreement
with Mr. Chang, Electronic Sensor Technology, L.P. agreed to convert $226,720 of
debt into the right to receive 226,720 shares of Bluestone common stock and a
warrant to purchase 113,360 shares of Bluestone common stock at $1.00 per share,
exercisable only if the trading price of such stock is at least $1.50 per share,
which Mr. Chang assigned to 3 Springs. Pursuant to the Debt Conversion Agreement
with Amerasia Technology, Electronic Sensor Technology, L.P. agreed to convert
$952,577 of debt into the right to receive 952,577 shares of Bluestone common
stock and warrants to purchase 476,289 shares of Bluestone common stock at $1.00
per share, exercisable only if the trading price of such stock is at least $1.50
per share. Following the Transaction, the Issuer issued such common stock and
warrants to the former debtholders of Electronic Sensor Technology, L.P., of
which 3 Springs received (i) 226,720 shares and a warrant to purchase 113,360
shares by virtue of the debt owed to Mr. Chang and (ii) 287,773 shares and a
warrant to purchase 143,887 shares, which represented Mr. Chang's portion of the
shares and warrants received by Amerasia Technology and distributed to its
shareholders.

         Mr. Chang was granted an option to purchase 80,000 limited partnership
interests of Electronic Sensor Technology, L.P. at $1.00 per limited partnership
interest on December 31, 2003. Such option was terminated, pursuant to a
Termination Agreement, in connection with the Transaction and was replaced with
an option to purchase 80,000 shares of Common Stock at $1.00 per share.

         On January 16, 2007, Francis Chang was granted an option under the
Issuer's 2005 Stock Incentive Plan to acquire 50,000 shares of Common Stock at
an exercise price of $0.24 per share. The options granted to Mr. Chang are fully
vested as of the date hereof.

         On March 5, 2007, Mr. Chang was granted an option under the Issuer's
2005 Stock Incentive Plan to acquire 40,000 shares of Common Stock at an
exercise price of $0.19 per share. The option shares were fully vested upon
grant.

         The summary descriptions contained in this Schedule 13D of the
Agreement and Plan of Merger and other related agreements and documents do not
purport to be complete and are qualified in their entirety by reference to the
complete texts of such agreements and documents listed in Item 6 and
incorporated herein by reference.

Item 4.  Purpose of Transaction

         The Reporting Persons engaged in the Transaction (as described in Item
3 above) based on the belief that the transaction would, among other things, (a)
provide the Issuer's business with increased access to capital, (b) enhance the
competitive position of the Issuer's business and (c) allow the Issuer's
business to expand its research and development, product commercialization and
manufacturing efforts.

         Neither Mr. Chang nor 3 Springs has any plans or proposals of the types
set forth in clauses (a) through (j), inclusive, of the instructions to Item 4
of Schedule 13D.

                                        2

Item 5.  Interest in Securities of the Issuer

         (a), (b) There were 155,853,385 shares of Common Stock issued and
outstanding and no shares of preferred stock issued and outstanding as of the
close of business on March 31, 2008. Each shareholder is entitled to one vote
for each share of Common Stock on all matters submitted to a shareholder vote.
As of the date hereof, 3 Springs has beneficial ownership (within the meaning of
Rule 13d-3 under the Exchange Act) and shared power to vote and shared
dispositive power over (i) 3,595,913 shares of Common Stock and (ii) 257,247
shares of Common Stock underlying warrants, which represent approximately 2.47%
of the shares of Common Stock deemed to be issued and outstanding as of March
31, 2008, taking into account the total amount of outstanding shares of Common
Stock beneficially owned by 3 Springs, including shares of Common Stock that 3
Springs has the right to acquire within 60 days pursuant to warrants, divided by
155,853,385, plus the shares of Common Stock that 3 Springs has the right to
acquire within 60 days pursuant to warrants. Beneficial and percentage ownership
by each of the Reporting Persons of Common Stock, and voting power held by each
Reporting Person, reported in this Item 5 is based on the foregoing and is
limited to the number of shares of Common Stock such Reporting Person may
acquire within 60 days of March 31, 2008.

         Mr. Chang beneficially owns 170,000 shares of Common Stock underlying
an option exercisable within 60 days of March 31, 2008, and by virtue of his
position as sole member of 3 Springs, beneficially owns (i) 257,247 shares of
Common Stock underlying warrants exercisable within 60 days of March 31, 2008
and held by 3 Springs and (ii) 3,595,913 shares of Common Stock held by 3
Springs, which, in the aggregate, represent approximately 2.57% of the Common
Stock deemed issued and outstanding as of March 31, 2008, taking into account
the total amount of outstanding shares of Common Stock beneficially owned by the
Reporting Persons, including shares of Common Stock that the Reporting Persons
have the right to acquire within 60 days pursuant to an option and warrants,
divided by 155,853,385, plus the shares of Common Stock that the Reporting
Persons have the right to acquire within 60 days pursuant to an option and
warrants. Mr. Chang has sole voting and dispositive power with respect to the
170,000 shares of Common Stock underlying the option held by Mr. Chang and
exercisable within 60 days of March 31, 2008. 3 Springs and Mr. Chang share
voting power and dispositive power with respect to the 3,595,913 shares of
Common Stock and 257,247 shares of Common Stock underlying warrants held by 3
Springs.

         (c) Neither of the Reporting Persons has effected any transaction in
the Issuer's securities in the last 60 days.

         (d) Not applicable.

         (e) Not applicable.

Item 6.  Contracts, Arrangements, Understandings or Relationships with Respect
         to Securities of the Issuer

         Mr. Chang is the sole member of 3 Springs.

         As part of the Transaction, Mr. Chang entered into or approved the
following agreements:

         (a) Agreement and Plan of Merger, dated as of January 31, 2005, by and
among Bluestone Ventures Inc., Amerasia Acquisition Corp., L&G Acquisition
Corp., Amerasia Technology Inc., and L&G Sensor Technology, Inc. (the form of
which is incorporated herein by reference from Exhibit 99.2 of Schedule 13D
filed on January 8, 2007).

         (b) Termination Agreement, dated January 22, 2005, between Electronic
Sensor Technology, L.P. and Francis Chang (incorporated herein by reference from
Exhibit 99.3 of Schedule 13D filed on January 8, 2007), pursuant to which all
prior option agreements by and between Electronic Sensor Technology, L.P. and
Francis Chang were terminated and replaced with an option to purchase shares of
Bluestone.

         (c) Debt Conversion Agreement, dated January 22, 2005, between
Electronic Sensor Technology, L.P. and Francis Chang (incorporated herein by
reference from Exhibit 99.4 of Schedule 13D filed on January 8, 2007), pursuant
to which the debt owed by Electronic Sensor Technology, L.P. to Francis Chang
was converted into the right to receive securities of Bluestone.

                                        3

         (d) Debt Conversion Agreement, dated January 22, 2005, between
Electronic Sensor Technology, L.P. and Amerasia Technology, Inc. (incorporated
herein by reference from Exhibit 99.5 of Schedule 13D filed on January 8, 2007),
pursuant to which the debt owed by Electronic Sensor Technology, L.P. to
Amerasia Technology was converted into the right to receive securities of
Bluestone.

         (e) Notice of Grant of Stock Option and Option Agreement (incorporated
by reference from Exhibit 10.2 of the Issuer's annual report on Form 10-KSB for
the fiscal year ended December 31m, 2004 filed April 15, 2005).

Item 7.  Material to be Filed as Exhibits

Exhibit 24.1      Power of Attorney for Francis Chang (incorporated by reference
                  from Exhibit 24.1 of Schedule 13D filed January 8, 2007).

Exhibit 24.2      Power of Attorney for 3 Springs, LLC (incorporated by
                  reference from Exhibit 24.2 of Schedule 13D filed January 8,
                  2007).

Exhibit 99.1      Joint Filing Agreement among the Reporting Persons, dated as
                  of April 7, 2008.

Exhibit 99.2      Form of Agreement and Plan of Merger, dated as of January 31,
                  2005, by and among Bluestone Ventures Inc., Amerasia
                  Acquisition Corp., L&G Acquisition Corp., Amerasia Technology
                  Inc., and L&G Sensor Technology, Inc. (incorporated by
                  reference from Exhibit 99.2 of Schedule 13D filed January 8,
                  2007).

Exhibit 99.3      Termination Agreement, dated January 22, 2005, between
                  Electronic Sensor Technology, L.P. and Francis Chang
                  (incorporated by reference from Exhibit 99.3 of Schedule 13D
                  filed January 8, 2007).

Exhibit 99.4      Debt Conversion Agreement, dated January 22, 2005, between
                  Electronic Sensor Technology, L.P. and Francis Chang
                  (incorporated by reference from Exhibit 99.4 of Schedule 13D
                  filed January 8, 2007).

Exhibit 99.5      Debt Conversion Agreement, dated January 22, 2005, between
                  Electronic Sensor Technology, L.P. and Amerasia Technology,
                  Inc. (incorporated by reference from Exhibit 99.5 of Schedule
                  13D filed January 8, 2007).

Exhibit 99.6      Form of Notice of Grant of Stock Option and Option Agreement
                  (incorporated by reference from Exhibit 10.2 of the Issuer's
                  annual report on Form 10-KSB for the fiscal year ended
                  December 31m, 2004 filed April 15, 2005).

                          *             *             *

                                        4

                                   SIGNATURES

         After reasonable inquiry and to the best of my knowledge and belief, I
certify that the information set forth in this statement is true, complete, and
correct.


Date: April 7, 2008                    /s/ Philip Yee
                                       -----------------------------------------
                                       Name:  Philip Yee
                                       Title: Attorney-in-Fact for Francis Chang

Date: April 7, 2008                    3 SPRINGS, LLC


                                       /s/ Philip Yee
                                       -----------------------------------------
                                       Name:  Philip Yee
                                       Title: Attorney-in-Fact

                                INDEX TO EXHIBITS

Exhibit 24.1      Power of Attorney for Francis Chang (incorporated by reference
                  from Exhibit 24.1 of Schedule 13D filed January 8, 2007).

Exhibit 24.2      Power of Attorney for 3 Springs, LLC (incorporated by
                  reference from Exhibit 24.2 of Schedule 13D filed January 8,
                  2007).

Exhibit 99.1      Joint Filing Agreement among the Reporting Persons, dated as
                  of April 7, 2008.

Exhibit 99.2      Form of Agreement and Plan of Merger, dated as of January 31,
                  2005, by and among Bluestone Ventures Inc., Amerasia
                  Acquisition Corp., L&G Acquisition Corp., Amerasia Technology
                  Inc., and L&G Sensor Technology, Inc. (incorporated by
                  reference from Exhibit 99.2 of Schedule 13D filed January 8,
                  2007).

Exhibit 99.3      Termination Agreement, dated January 22, 2005, between
                  Electronic Sensor Technology, L.P. and Francis Chang
                  (incorporated by reference from Exhibit 99.3 of Schedule 13D
                  filed January 8, 2007).

Exhibit 99.4      Debt Conversion Agreement, dated January 22, 2005, between
                  Electronic Sensor Technology, L.P. and Francis Chang
                  (incorporated by reference from Exhibit 99.4 of Schedule 13D
                  filed January 8, 2007).

Exhibit 99.5      Debt Conversion Agreement, dated January 22, 2005, between
                  Electronic Sensor Technology, L.P. and Amerasia Technology,
                  Inc. (incorporated by reference from Exhibit 99.5 of Schedule
                  13D filed January 8, 2007).

Exhibit 99.6      Form of Notice of Grant of Stock Option and Option Agreement
                  (incorporated by reference from Exhibit 10.2 of the Issuer's
                  annual report on Form 10-KSB for the fiscal year ended
                  December 31m, 2004 filed April 15, 2005).