type
  TTimerThread = class(TThread)
  private
    hClose : Cardinal;
  public
    constructor Create;
    destructor Destroy; override;

    procedure CloseMe;
    procedure Execute; override;
  end;


{ TTimerThread }

procedure TTimerThread.CloseMe;
begin
  SetEvent(hClose);
end;

constructor TTimerThread.Create;
begin
  inherited Create(false);
  hClose := CreateEvent(nil, true, false, nil)
end;

destructor TTimerThread.Destroy;
begin
  CloseMe; // schleife beenden
  CloseHandle(hClose);
  inherited;
end;

procedure TTimerThread.Execute;
var dw : Cardinal;
begin
  repeat
    dw := WaitForSingleObject(hClose, 60000);
    if dw = WAIT_TIMEOUT then
       Windows.Beep(200, 200); // mache irgentwas
  until (dw = WAIT_OBJECT_0) or Terminated; // beendet
end;