These increase the output current capacity. The resistors should be approximately 1KΩ, 1W or similar. They are wired to the DAC20 output connector SK2 1 to 8. The "12V" point comes from the middle terminal of the 3 way screw connection for each output. The appropriate jumper needs to be set for continuous power (see manual section 3.2).
You may find you need an aux voltage feed to the DAC20 above +12v: 16-18V DC may be appropriate.
(Please note we've increased the recommended power rating, for cases where a higher supply voltage than 12v is used AND the external resistors)
The DAC20 can NOT drive the newest Cobalt IP motors: these need a higher current when moving than the DAC20 can provide. The Output Adapter circuit we have on the website works fine with them, and we are considering making that available as a product.