| ??? 06/13/12 13:57 Read: times |
#187693 - Logically, not physically Responding to: ???'s previous message |
Per Westermark said:
Richard Erlacher said:
HI wanted to use the DAC's in place of some of the pot's but in parallel with them, so the instrument could be driven by software if desired, but could also be hand-operated. Doesn't sound easy to have a DAC and a pot in parallel. The POT and DAC were separated by an analog multiplexer. The theory was that a switch could control whether the DAC's or the POT's were in use to set the various control voltages. It was very tempting to make it overly complex. I'm not even sure the thing was ever completed. You didn't consider using a rotary encoder to allow you manual control of the DAC?
No ... nobody thought of that. It was just a way for us to use those free samples of the MAX038 that we all seemed to have at the time. It looked like a really "pregnant" project. I was disappointed that the frequency topped out at 20 MHz, others were more concerned about the trouble in making the output voltage swing 15-20 volts to either side of common, as was usual with old-style signal generators. At the time, I was enamored of being able to phase-lock two generators (that's what the MAX038 is, after all) of different frequency, so I liked it. I had to phase-lock two, and sometimes three of the TEK FG504's that I had. ISTR that was in the early '90's ... We weren't terribly busy at the time. RE |
