The originals used a now nearly unobtainable SAD512D chip, but the wizards on FSB converted it to work with an MN3007. Now that those are also hard to get a hold of, I’ve laid this out for an MN 3207–which is almost the same as the 3007, just with a slightly different pinout for power and ground. But if you want to use a 3007, I’ve included a daughter board that will let you use it (it will also work to use a 3207 in place of a 3007). This will best fit in a 125B and the schematic can be found here.
