public void cargar_controles()
{
conexion.conexion c = new conexion.conexion();
c.cargar_datagrid(dg_conductor, "select * from conductor");
c.cargar_combox(cb_interno, "select * from interno", "interno", "interno");
c.cargar_combox(cb_placa, "select * from auto", "placa", "placa");
}