THIS NOTE AND THE  SECURITIES  TO BE ISSUED  UPON ITS  CONVERSION  HAVE NOT BEEN
REGISTERED  UNDER THE UNITED  STATES  SECURITIES  ACT OF 1933,  AS AMENDED  (THE
"ACT"),  AND MAY NOT BE  OFFERED OR SOLD IN THE  UNITED  STATES  (AS  DEFINED IN
REGULATION S UNDER THE ACT) OR TO OR FOR THE ACCOUNT OR BENEFIT OF U.S.  PERSONS
(AS DEFINED IN REGULATION S) EXCEPT PURSUANT TO REGISTRATION UNDER THE ACT OR AN
EXEMPTION FROM THE  REGISTRATION  REQUIREMENTS  OF THE ACT AND APPLICABLE  STATE
SECURITIES LAWS.  MOREOVER,  THIS NOTE MAY NOT BE EXERCISED BY OR ON BEHALF OF A
U.S. PERSON UNLESS REGISTERED UNDER THE ACT OR AN EXEMPTION FROM REGISTRATION IS
AVAILABLE.

APRIL 7, 2000                                                    U.S.$10,000,000

                             OPAL TECHNOLOGIES, INC.

                               4% CONVERTIBLE NOTE

     THIS  NOTE  is  one  of  a  duly  authorized   issue  of  Note(s)  of  Opal
Technologies,  Inc., a corporation duly organized and existing under the laws of
the State of Nevada (the "Company"),  designated as its 4% Convertible Notes due
on April 9, 2003 in an  aggregate  principal  amount not  exceeding  Ten Million
United States Dollars (U.S.$10,000,000).

     FOR  VALUE  RECEIVED,  the  Company  promises  to pay to  Marlborough  Gold
Limited,  a  wholly-owned  subsidiary of United Power  Investment  Limited,  the
registered  holder hereof and its  successors  and assigns (the  "Holder"),  the
principal  sum of Ten Million  United  States  Dollars  (U.S.$10,000,000)  on or
before April 9, 2003 (the  "Maturity  Date") plus  interest on the principal sum
outstanding at the rate of 4% per annum payable quarterly in arrears. Accrual of
interest  shall  commence from the date of any advance and shall  continue until
payment  in full  of the  principal  sum has  been  made or duly  provided  for.
Interest  will be paid to the  person  in whose  name  this Note (or one or more
predecessor  Notes)  is  registered  on the  records  of the  Company  regarding
registration and transfers of the Notes (the "Note Register"). The principal of,
and  interest  on,  this Note are payable in such coin or currency of the United
States of  America as at the time of  payment  is legal  tender  for  payment of
public and private  debts,  and shall be paid by wire  transfer as designated in
writing  by the  Holder  hereof  from  time to time.  The  Company  will pay the
principal of and all accrued and unpaid interest due upon this Note.
<PAGE>

     This Note is subject to the following additional provisions:

     1. The Company shall be entitled to withhold from all payments of principal
of, and  interest  on, this Note any amounts  required to be withheld  under the
applicable  provisions of the United States income tax or other  applicable laws
at the time of such payments.

     2. This Note has been issued subject to investment  representations  of the
original  purchaser  hereof and may be transferred or exchanged in the U.S. only
in  compliance  with the  Securities  Act of 1933,  as amended (the "Act"),  and
applicable  state securities laws. Prior to due presentment for transfer of this
Note,  the  Company  and any agent of the  Company may treat the person in whose
name this Note is duly  registered on the  Company's  Note Register as the owner
hereof for the purpose of  receiving  payment as herein  provided  and all other
purposes,  whether or not this Note be overdue,  and neither the Company nor any
such agent shall be affected by notice to the contrary.

     3. The Holder of this Note is  entitled,  at its option,  at any time after
October  10,  2000,  to convert the  original  principal  amount (the  "Original
Amount") of this Note into fully paid and non-assessable shares of common stock,
$.001 par value, of the Company (the "Common Stock") at a conversion  price (the
"Conversion Price") equal to US$0.20; provided,  however, that the Company shall
be required to convert no less than US$1 million of the Original Amount.

     4.  Conversions  of this Note  shall be  effectuated  by  surrendering  the
Note(s) to be converted  (with a copy, by facsimile or courier,  to the Company)
to the Company with the Form of Conversion Notice (attached hereto as Exhibit A)
executed  by the  Holder of this Note  evidencing  such  Holder's  intention  to
convert  this Note or a  specified  portion  (as  above  provided)  hereof,  and
accompanied,  if required by the Company,  by proper assignment hereof in blank.
No  fractional  or scrip  representing  fractions  of  shares  will be issued on
conversion, but the number of shares issuable shall be rounded up to the nearest
whole number of shares. The date on which notice of conversion is given shall be
deemed to be the date on which the Holder  has  delivered  this  Note,  with the
conversion  notice duly executed,  to the Company,  or if earlier,  the date set
forth in such notice of conversion if the Note is received by the Company within
three business days thereafter.

     5. No amount of  accrued  but  unpaid  interest  otherwise  payable  by the
Company shall be subject to conversion  and the Company shall be bound to accrue
and pay all interest on all principal  balances  outstanding up to the date that
Notice of Conversion is served on the Company.
<PAGE>

     6. No  provision of this Note shall alter or impair the  obligation  of the
Company,  which is absolute  and  unconditional,  to pay the  principal  of, and
interest on, this Note at the time, place and rate, and in the coin or currency,
herein prescribed.  This Note ranks equally and ratably with all other Notes now
or hereafter issued under the terms set forth herein.

     7. The  Company  shall be  entitled,  at its sole  option  and upon  proper
notice, to automatically  convert ("Forced Conversion") any amount remaining due
and  payable  under this Note into  Common  Stock,  and only if, the closing bid
price of the Common  Stock is greater than $2.00 for a period of at least twenty
(20)  consecutive  trading days ending not more than two business  days prior to
giving of notice by the Company of its election to cause such Forced Conversion.
In the event the Company elects to cause a Forced Conversion,  the Company shall
notify  the Holder in  writing  ("Notice  of Forced  Conversion")  by  facsimile
transmission  and by certified  mail at the number and address set forth for the
Holder  below,  or at such other number and address as the Holder may notify the
Company  of from time to time.  Notice of Forced  Conversion  shall be deemed to
have been given as of the date such notice was transmitted by facsimile or three
business days after the date depositee in the United States mail,  certified and
postage pre-paid, whichever is earlier. The Conversion Price with respect to any
such Forced Conversion shall be the then applicable Conversion Price on the date
of such  Notice  of  Forced  Conversion.  Upon  receipt  of a Notice  of  Forced
Conversion,  the Holder shall promptly return to the Company this Note and, upon
receipt by the Company of the Note, the Company shall issue the shares  issuable
as a result of such Forced Conversion.

     8. The Company hereby  expressly waives demand and presentment for payment,
notice of nonpayment,  protest, notice of protest, notice of dishonor, notice of
acceleration  or intent to accelerate,  bringing of suit and diligence in taking
any action to collect  amounts  called for  hereunder  and shall be directly and
primarily  liable  for the  payment  of all sums  owing and to be owing  hereon,
regardless  of and  without any  notice,  diligence,  act or omission as or with
respect to the collection of any amount called for hereunder.

     9. The Company agrees to pay all costs and expenses,  including  reasonable
attorney's  fees,  which may be incurred by Holder in collecting  any amount due
under this Note.

     10. The following shall constitute "Events of Default" under this Note:

     (a)  Any default in the payment of principal or interest on this Note;

     (b)  If the Company  shall fail to perform or observe  any other  covenant,
          term,  provision,  condition,  agreement or  obligation of the Company
          under this Note and such failure shall  continue  uncured for a period
          of seven (7) days after notice from the Holder of such failure;
<PAGE>

     (c)  If the Company shall (i) become  insolvent,  (ii) admit in writing its
          inability  to pay its debts as they mature,  (iii) make an  assignment
          for  the  benefit  of  creditors  or  commence   proceedings  for  its
          dissolution,  or (iv)  apply for or consent  to the  appointment  of a
          trustee,  liquidator or receiver for it or for a  substantial  part of
          its property or business;

     (d)  If a  trustee,  liquidator  or  receiver  shall be  appointed  for the
          Company or for a substantial  part of its property or business without
          its consent and shall not be discharged  within thirty (30) days after
          such appointment;

     (e)  If any governmental  agency or any court of competent  jurisdiction at
          the  instance  of any  governmental  agency  shall  assume  custody or
          control of the whole or any  substantial  portion of the properties or
          assets of the Company and shall not be  dismissed  within  thirty (30)
          days thereafter;

     (f)  If any money  judgment,  writ or  warrant  of  attachment,  or similar
          process,  except  mechanics and  materialmen's  liens  incurred in the
          ordinary  course  of  business,  in  excess  of  US$1,000,000  in  the
          aggregate  shall be entered or filed against the Company or any of its
          properties  or other  assets and shall remain  unvacated,  unbonded or
          unstayed  for a period of fifteen (15) days or in any event later than
          five (5) days prior to the date of any proposed sale thereunder;

     (g)  If bankruptcy,  reorganization,  insolvency or liquidation proceedings
          or other  proceedings  for relief under any  bankruptcy law or any law
          for the  relief of  debtors  shall be  instituted  by or  against  the
          Company  and,  if  instituted  against  the  Company,   shall  not  be
          dismissed,  stayed or  bonded  within  ninety  (90)  days  after  such
          institution  or the Company shall by any action or answer  approve of,
          consent to, or acquiesce in any such proceedings or admit the material
          allegations  of, or default in answering a petition  filed in any such
          proceeding; or

     (h)  The Common Stock (as a class) is suspended  from being listed or dealt
          with on the Bulletin  Board of NASDAQ or a recognized  stock  exchange
          for a continuos period of 14 days due to the default of the Company or
          the  Common  Stock  ceases  to be listed  on the  Bulletin  Board or a
          recognized stock exchange.

Upon the occurrence of an Event of Default, then, or at any time thereafter, and
in each and every such case, unless such Event of Default shall have been waived
in writing by the Holder (which waiver shall not be deemed to be a waiver of any
subsequent  default)  at the  option  of the  Holder  and in the  Holder's  sole
discretion,  the Holder may  consider  this Note  immediately  due and  payable,
without  presentment,  demand,  protest or notice of any kind,  all of which are
hereby  expressly  waived,  anything herein or in any note or other  instruments
contained to the contrary notwithstanding,  and the Holder may immediately,  and
without  expiration of any period of grace,  enforce any and all of the Holder's
rights and remedies  provided herein or any other rights or remedies afforded by
law.
<PAGE>

     11. For so long as any amount payable under this Note remains  unpaid,  the
Company shall furnish to the Holder the following information:

     (a)  No later than ninety (90) days  following the end of each fiscal year,
          beginning with the fiscal year ending December 31, 2000,  consolidated
          balance  sheets,  statements of income and statements of cash flow and
          shareholders'  equity of the  Company  and its  subsidiaries,  if any,
          prepared in accordance with generally accepted  accounting  principles
          ("GAAP"),  and  audited by a firm of  independent  public  accountants
          (i.e., Form 10-K or Form 10-KSB).

     (b)  Within  forty-five (45) days after the end of each quarter (except the
          fourth  quarter) of each fiscal  year,  consolidated  balance  sheets,
          statements  of income and  statements  of cash flow of the Company and
          its subsidiaries, if any (i.e., Form 10-Q or Form 10-QSB).

     12. The Company  covenants and agrees that until all amounts due under this
Note have been paid in full,  by  conversion  or  otherwise,  unless  the Holder
waives compliance in writing, the Company shall:

     (a)  Give  prompt  written  notice to the Holder of any Event of Default as
          defined in this Note or of any other  matter which has resulted in, or
          could reasonably be expected to result in, a materially adverse change
          in its financial condition or operations.

     (b)  Give  prompt  written  notice to the  Holder of any  claim,  action or
          proceeding  which, in the event of any unfavorable  outcome,  would or
          could  reasonably be expected to have a material adverse effect on the
          financial condition of the Company.

     (c)  At all times  reserve and keep  available  out of its  authorized  but
          unissued  stock,  for the purpose of effecting the  conversion of this
          Note such  number  of its duly  authorized  shares of Common  Stock as
          shall from time to time be sufficient to effect the  conversion of the
          outstanding  principal  balance  of this  Note  into  shares of Common
          Stock.

     (d)  Upon receipt by the Company of evidence reasonably  satisfactory to it
          of the loss, theft,  destruction or mutilation of this Note and (i) in
          the  case of loss,  theft  or  destruction,  of  indemnity  reasonably
          satisfactory to it, or (ii) in the case of mutilation,  upon surrender
          and  cancellation  of this Note,  the Company,  at its  expense,  will
          execute  and deliver a new Note,  dated the date of the lost,  stolen,
          destroyed or mutilated Note.
<PAGE>

     (e)  In the event of a merger,  consolidations or sale of substantially all
          of the  Company's  assets or any other  business  combination,  at the
          option of the Holder, the note may be converted,  in whole or in part,
          into shares of common stock of the Company as provided in Paragraph 3,
          except and save that the data of October 10, 2000 shall not apply.  In
          addition,  upon the  occurrence  of any of the  following  events (the
          "Relevant Event"), the conversion price specified in paragraph 3 shall
          be adjusted in such manner as shall be certified by the then  auditors
          of  the  Company  (the  "Auditors")  as  fair  and  reasonable  in the
          circumstances.  A copy of the certificate of the Auditors  relating to
          any such adjustment shall be given by the Company to the Holder within
          14 days of the occurrence of the Relevant Event:

          (i)  any  variation in the share  capital of the Company  arising from
               any reduction,  sub-division or consolidation of share capital or
               the  issue  of  any  share  capital   (including  any  securities
               convertible   into  share  capital  or  warrants  or  options  to
               subscribe  for any share  capital)  by way of  capitalization  of
               profits or reserves or in connection  with an offer made pro rata
               to shareholders of the Company,  except (a) as  consideration  or
               part  consideration for the acquisition of any assets or business
               by the Company or any of its subsidiaries, or (b) pursuant to the
               exercise of  subscription  rights  under the share option plan of
               the Company; or

          (ii) any distribution of the Company's  capital assets to shareholders
               of the  Company  pro  rata,  whether  in cash or  specie,  except
               dividend paid out of the net profits attributable to shareholders
               of the Company for each financial year of the Company.

     (f)  The  Company  shall not in any way modify the rights  attached  to the
          Common Stock as a class or attach any special restrictions thereto.

     (g)  The  Company  shall  not  issue  or pay up  any  securities  by way of
          capitalisation  of profits or reserves  other than (i) by the issue of
          fully paid  shares of Common  Stock to holders of its shares of Common
          Stock;  or (ii) by the  issue  of  shares  of  Common  Stock  or other
          securities of the Company or any  subsidiary of the Company  wholly or
          partly  convertible into, a rights to acquire,  shares of Common Stock
          to  offices or  employees  of the  Company or any of its  subsidiaries
          pursuant to any employee or executive  share  scheme;  or (iii) by the
          issue of shares of Common Stock in lieu of a cash dividend pursuant to
          a scrip dividend scheme of the Company.
<PAGE>

     (h)  The Company  shall not create or permit to be issued any equity  share
          capital  other  than  Common  Stock,  provided  that  nothing  in this
          sub-paragraph  shall prevent (i) any  consolidation or sub-division of
          the Common Stock; or (ii) the issue of equity share capital which does
          not participate in dividends before a certain date, or in respect of a
          certain  financial period but is pari passu in all other respects with
          the  Common  Stock;  or (iii)  the issue of equity  share  capital  to
          officers  or  employees  of the  Company  or  any of its  subsidiaries
          pursuant to an employee or executive option plan.

     (i)  The Company shall procure that (i) no securities issued by the Company
          shall be converted into shares of Common Stock or exchanged for shares
          of Common Stock except in accordance  with the terms of issue thereof,
          (ii) no  securities  issued by the Company  without  rights to convert
          into shares of Common  Stock or to be  exchanged  for shares of Common
          Stock shall  subsequently  be granted such rights and (iii) at no time
          shall there be in issue shares of Common  Stock of  differing  nominal
          values.

     (j)  If an offer is made to the  holders of Common  Stock (or such  holders
          other than the offeror  and/or any company  controlled  by the offeror
          and/or persons acting in concert with the offeror) to acquire all or a
          portion of the Common Stock,  the Company shall  forthwith give notice
          of such offer to the Holder and use its best endeavours to insure that
          a similar  offer is  extended in respect of the shares  issuable  upon
          conversion of the Note.

     (k)  The Company  shall not make any  distribution  in specie to holders of
          Common Stock.

     (l)  The Company shall use its best endeavors (a) to maintain a listing for
          all the issued shares of Common Stock on the Bulletin  Board of NASDAQ
          or a  recognized  stock  exchange as the Company may from time to time
          determine,  (b) to obtain and maintain a listing on the Bulletin Board
          of NASDAQ  (or a  recognized  stock  exchange)  for all  shares of the
          Common Stock issued on the exercise of the Conversion Rights attaching
          to the Note and (c) to obtain a listing  for all  shares of the Common
          Stock are for the time being listed and will  forthwith give notice to
          the holder of the Note of the  listing or  delisting  of shares of the
          Common Stock by any such stock exchanges.

     (m)  As soon as possible and in any event not later than seven (7) business
          days after the  happening  of a  Relevant  Event,  give  notice to the
          Holder advising it of the date on which the relevant adjustment of the
          Conversion  Price is likely to become  effective  and of the effect of
          exercising its conversion rights pending such date.

     The  Company  shall  ensure  that all shares of Common  Stock  issued  upon
conversion of the Note will be duly and validly issued,  credited as fully paid,
rank pari passu in all respects with the existing shares outstanding at the date
on which the conversion  notice is serviced on the Company and registered in the
name of the Holder or its nominees.

     13. The Holder of this Note agrees to bear the cost of any U.S. withholding
tax on interest payable under this Note.

     14. No recourse  shall be had for the payment of the  principal  of, or the
interest on, this Note, or for any claim based  hereon,  or otherwise in respect
hereof,  against any incorporator,  shareholder,  officer or director,  as such,
past, present or future, of the Company or any successor corporation, whether by
virtue of any constitution, statute or rule of law, or by the enforcement of any
assessment or penalty or otherwise,  all such liability being, by the acceptance
hereof and as part of the consideration  for the issue hereof,  expressly waived
and released.

     15. The Holder of this Note, by acceptance hereof, agrees that this Note is
being acquired for investment and that Holder will not offer,  sell or otherwise
dispose  of this Note or the  shares  of Common  Stock  issuable  upon  exercise
thereof except under  circumstances  which will not result in a violation of the
Act or any applicable state Blue Sky law or similar laws relating to the sale of
securities.

     16.  In case any  provision  of this  Note is held by a court of  competent
jurisdiction  to be excessive in scope or  otherwise  invalid or  unenforceable,
such provision shall be adjusted rather than voided, if possible,  so that it is
enforceable to the maximum extent possible,  and the validity and enforceability
of the  remaining  provisions  of this Note will not in any way be  affected  or
impaired thereby.

     17. This Note constitutes the full and entire  understanding  and agreement
between the Company and the Holder with respect to the subject  hereof.  Neither
this Note nor any term hereof may be amended,  waived,  discharged or terminated
other than by a written instrument signed by the Company and the Holder.

     18. This Note shall be governed by the  construed  in  accordance  with the
laws of the State of Nevada.
<PAGE>

     IN WITNESS  WHEREOF,  the  Company has caused  this  instrument  to be duly
executed by an officer thereunto duly authorized.




                                                     OPAL TECHNOLOGIES, INC.


Dated: April 7, 2000                                 By:/s/ John Koon
                                                     --------------------------
                                                     Name:John Koon
                                                     Title:President

Agreed and Accepted by:
Marlborough Gold Limited


/s/ Eric Cheng
------------------------
Authorized signatory
Name:Eric Cheng
Title:Director
Dated:April 7, 2000