Hi,
I don't know this board and have no affiliations with companies or sellers but commenting as an electronic enthusiast.
Do notice there are two variations of this board. One has additional components in the motor outputs in the form of 2 white ceramic
power resistors at zero ohm for driver ic protection and an inductor at the 5 volt power input for better noise suppression to the
sensitive control circuits.
The board is professionally laid out and the current setting and sense resistors are at the bottom layer so users not likely to touch and short them out. It has dip switches to select fine steping modes and current decay ( DCY ). It also has 24 volt input glass fuse and 6 ampere diode
for reverse current protection. More importantly the control signals from PC parallel port are isolated by opto couplers from the high power
motor power supply to protect PC. Of course you can mod the other board to have these extras like fuse, resistors and inductor.
Lastly there is current setting adjusting potentiometer and the sliding switch silkscreen say " half or full flow" which is linked to current adjust but I don't really know for sure what it means. Does it mean if half or full select will mean whatever adjustment from blue pot it will reflect accordingly? If I were to choose I'll certainly choose the one with additional components. Forgot to mention red led for power on and green led for driver ic activity?
Also notice the screws use triangle bits so make it harder for curious
people to open up but not difficult to buy triangle screw drivers.
Sorry the inductor L1 could be for 24volt line.