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| Why HP power supplies doesnt have a obvious feedback loop? |
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| duak:
Most of the hp lab power supplies were designed using the same basic idea of a floating regulator. The output voltage is determined by a command voltage that is derived from a reference current passing through a variable resistance or just from a voltage that is provided from some external source. This allowed them to be to be programmed externally, paralleled to increase current, put in series to increase voltage, and to sense the load voltage to compensate for voltage loss in the cabling. This makes them very versatile and comes in handy when the supplies are used in automatic testing. I didn't appreciate how brilliant the idea was until I started using the supplies. Some of the Lambda and Kepco supplies use a similar idea. Here's a link to a document that describes the idea: https://www.hpl.hp.com/hpjournal/pdfs/IssuePDFs/1962-07.pdf Here's a later version that goes into more detail: http://hpmemoryproject.org/an/pdf/an_06-65.pdf Cheers, |
| jaycee:
--- Quote from: Efe_114 on March 13, 2019, 07:42:28 pm ---What is advantages/disadvantages of this method? Why is this used in this design? I am a knowladge addict sorry for so much questions. Lemme guess, is it so OpAmps will never get out of supply voltage? --- End quote --- Well it simplifies design greatly as the opamps do not have to see the full supply voltage, which means a wide range of opamps can be used. It also means the supply voltages for the opamps can be well regulated and low noise, increasing PSRR of the main regulator. It also scales very well.. for example it's no problem for the main output to be 18V, 30V, 60V, whatever you need... without having to modify the regulation loop much. |
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