Here's a pic taken in 1981 of my old Raleigh Sports with a big headlight from Bicycle Lighting Systems. It used a 6v sealed beam lamp that had a trapezoidal pattern. I think they were designed for scooters. Absolutely the best beam pattern I've ever seen for a bike headlight. The NiCd battery is in the water bottle holder on the seat tube. I still have two of the lamps. The housing was a typical 4" diameter piece typically seen on tractors and probably still available in the hardware store. Whoppin' huge amount of light for the time!