It's actually very easy. I was stuck baby sitting a substation today so I drew up a circuit. Mine included some output resistance, transorb, and fuse protection. This sounds like stuff you don't need. My designs often translate signals to drive a SCADA input 1000's of feet away, so I have to protect them.
OK, the way I see it, you need.
1.) 1, 24VCT transformer,give or take.
2.) 1 bridge rectifier.
3.) 2, quad op amps.
4.) 1, pos. regulator
5.) 2, neg. regulators
6.) 1, 625 ohm precision resistor.
7.) 8 pots, multi-turn if nec.
8.) A hand full of filter & bypass caps
9.) Something to build it in or on.
10.) Line cord, input fuse, switches, VM, mAM, if you aren't using a DMM and need to read values.
OK, all this stuff just counts if you wish to have 4, low impedance 0-10 volt sources and 4, precise 0 to 10 volt to 4 to 20mA converters. One quad op amp would be set up as op amp followers and the other as 4 V-A.
But if you don't need all this stuff and just want to drive inputs, go to the next post. I'll be doing a couple of drawings and submitting them.
Joe
[This message has been edited by JoeTestingEngr (edited 08-01-2006).]
