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unit noise_p;

interface

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

type
  TForm1 = class(TForm)
    Button1: TButton;
    Timer1: TTimer;
    Label1: TLabel;
    procedure Button1Click(Sender: TObject);
    procedure FormCreate(Sender: TObject);
    procedure Timer1Timer(Sender: TObject);
  private
    { Private declarations }
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  hoch:boolean;
  i:integer;

implementation

{$R *.dfm}

procedure TForm1.Timer1Timer(Sender: TObject);
begin
windows.Beep(i,53);
if hoch then i:=i+10 else i:=i-10;
if i=2300 then hoch:=false;
if i=300 then hoch:=true;
label1.Caption:='Frequenz: '+inttostr(i);
end;

procedure TForm1.FormCreate(Sender: TObject);
begin
i:=20;
hoch:=true;
end;

procedure TForm1.Button1Click(Sender: TObject);
begin
timer1.Enabled:= not timer1.Enabled;
end;

end.