On my Pfaff 1471 a red light comes on when the bobbin is low. It allows you to stop sewing at a good place like after a seam is finished. It actually lets you sew for quite a little bit more. You learn about how far you can go after the light comes on by experience. I love this feature!
Originally Posted by Tropical
My machine doesn't ding (it would annoy me), but it does have a tiny red light above the needle that blinks on when the bobbin is low. I have learned approximately how much further I can sew when that happens. I like that tiny red blinking light.