On Wed, May 10, 2017 at 1:44 AM, Evan Koblentz via vcf-midatlantic < vcf-midatlantic@lists.vintagecomputerfederation.org> wrote:
I wanted to test one of the Lego motors without setting up the whole kit. The motor is designed for 4V DC. Dug through my bin of random wall warts. Closest I could find is 5V DC (and 0.5A but I'm not sure if that matters). Snipped off the wart's barrel connector, spliced a mini-banana lead to each wire, and the motor happily spun away. When I tested the Lego computer interface port voltage it showed around 3.7x on my multimeter whereas the wart produces 5 true. Will I cause any long-term damage to the 30-year-old Lego motor by running it at 25% higher voltage than intended?
The 80s Lego motors were marked at 4.5v, whenever you see them for sale. Many of the wall-warts have very weak regulation, if it's the modern variety, and none if much older. I don't recall the current rating on the motor, but you like to find a power supply with enough current, your 0.5A might be just enough Then the windings in the armature of the motor will begin increase their heat dissipation, not good if running for long periods. Once it does get hot, the windings can deform and possibly short together as the enamel insulation beings to melt. If you constantly run the motor at the higher voltage, it's not that much but still, I think it would take a long time to get hot at just 5v, but longer age is a factor, making it further weak The simplest test is the sniff test, if you smell anything emanating from the motor, and not ozone from the commutation contacts, but rather chemical smell, it might be too late. You're safe by with just 2x C or D cell batteries, a battery holder, or recycle an old-school flashlight into a power supply Dam