Collected from various spots around the Web, including evanescent eBay listings, and reformatted to make sense, these specs describe the 2M415 stepper driver: a smaller sibling of the 2M542 family.
Blurb
- +15 to 40VDC Supply Voltage
- H-Bridge, 2 Phase Bi-polar Micro-stepping Drive
- Suitable for 2-phase, 4, 6 and 8 leads step motors, with Nema size 16 to 23
- Output current selectable from 0.21 ~ 1.5A peak
- Compact credit card size package
- Optically isolated single ended TTL inputs for Pulse, Direction and Enable signal inputs
- Selectable resolutions up to 12800 steps
- Over Voltage, Coil to Coil and Coil to Ground short circuit protection.
Electrical specs
| Parameters | Min | Typ | Max | Unit |
| Output Current (Peak) | 0.21 | – | 1.5 | Amp |
| Supply voltage | 15 | 36 | 40 | VDC |
| Logic Input Current | 7 | 10 | 16 | mA |
| Pulse input frequency | 0 | – | 200 | KHz |
| Low Level Time | 2.5 | µsec |
Mechanical specs
| Cooling | Natural Cooling or Forced Convection |
| Space | Avoid dust, oil, frost and corrosive gases |
| Ambient Temp | 0 °C – 50 °C |
| Humidity | 40 – 80 %RH |
| Vibration | 5.9 m/s² Max |
| Storage Temp. | -10 °C – 80 °C |
| Weight | Approx. 150 gram |
Dimensions
Wiring diagram
Notice that the driver requires a positive voltage for the optoisolators.
Of course, the box from halfway around the planet contained HB-415M drivers. Should you go looking with the usual keywords, you’ll find that HB-number turns up mostly “House Bill number” citations from various state legislatures. Popping the top off the drive reveals www.sikesai.com, which eventually produces a description and PDF datasheet for the driver. It turns out to be an “Ultra Low Noise” driver, whatever that means, with reasonably standard specifications that correspond more-or-less to the 2M415 drivers I thought I was getting.
The Smell of Molten Projects in the Morning 
By low noise, they mean low audible noise since it switches at ultrasonic frequencies. I find that completely untrue as mine make an audible hiss in the motors but I just need a few more years of hearing loss and then I won’t know about it. YMMV.
Or maybe they have a capacitor on the input that’s supposed to filter out the electrical noise? Sort of like a blender with “Solid State Speed Control” that turns out to have a (one, singular) diode rectifying the power-line input for the half-speed setting. Ya never know!
Without changing a thing, the Sherline’s motors have gotten quieter and quieter over the years. They still drive Mary out of the Basement Laboratory, though.
motors have gotten quieter
Yeah, happened to me, too. Chainsaws used to be way too loud, but over the years (and too much reconstructive ear surgery for otosclerosis) my hearing is charitably described as “low normal”. On a good day.
I’m beginning to suspect that might apply to more than just my ears… [grin]