Timer в рантайме

[amandra]

есть класс
в нем есть переменная типа TTimer

 TAddBuyParam = class
     Timer : TTimer;
     PS_from : real;
     PS_to : real;
     Time_delay : real;
     PSDecVolume : Currency;
     constructor create(aPS_from, aPS_to, aTime_delay, aPSDecVolume: real);
     destructor destroy; Override;
   end;

не могу разобраться как описать обработчик события для onTimer
подскажите

[Баламут]

unit Unit1;

interface

uses
  Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
  Dialogs, ExtCtrls, StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    procedure Button1Click(Sender: TObject);
  private
    Count: integer;
    Timer1: TTimer;
    procedure MyOnTimer(Sender: TObject);

    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.dfm}

procedure TForm1.Button1Click(Sender: TObject);
begin
  Count := 0;
  Timer1 := TTimer.Create(Form1);
  Timer1.Interval := 500;
  Timer1.Enabled := false;
  Timer1.OnTimer := MyOnTimer;
  Timer1.Enabled := true;
end;

procedure TForm1.MyOnTimer(Sender: TObject);
begin
  Form1.Caption := IntToStr(Count);
  Inc(Count);
end;

end.