Hi Nirmal, thanks for your answer.
You are right, optocouplers (or relais) are the only pieces I still need. Also, I have nothing against soldering my own little 'board' in this situation. Maybe you could suggest me some good optocouplers. I am not experienced with hardware, but I see a problem in the electrical characteristics of the optocouplers: When they switch a measuring signal, the voltage drop should be minimal (maybe < 1uV). Also, if they switch lines for current measurement their resistance should be less then 0.1 Ohm. But I could do away with the 0.1 Ohm requirement by providing a voltage measurement across shunt resistors. I should probably do that anyway since this simplifies the measurement: I only need one (voltage) input to the Keithley 2000. Best regards Johannes On Thu, 25 Mar 2004 07:30:14 -0600 (CST), Nirmal Sharma <[EMAIL PROTECTED]> wrote: >Hi Johannes, > >why do u require switcher??. As u mentioned u are using the >optocoupler which will take digital TTL o/p from DAQ card & switch the >respective analog channel, you dont require any other switcher. Also >switching 100 mV through TTL outputs should not be any problem. > >Hope it works. Your feedbacks are welcome. > >Best Regards, >Nirmal Sharma
