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Post by qtsearcher on Jan 20, 2022 21:23:48 GMT -5
Hi, I am working on the Lakeshore power supply 642, and want to use the external current programming. I want to program the current as a sum of a dc and a small sine ac, from the SR 830. But the Lakeshore power supply connection is confusing. The power supply is externally controlled by Lakeshore 475 Gaussmeter, while the Gaussmeter is connected to the computer through a GPIB. Could you give me some suggestions?
Best,
Tao
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Post by Lake Shore Jeff M on Jan 21, 2022 8:12:10 GMT -5
The Model 475 Gaussmeter provides a +/-10VDC control signal to the Model 642. The Model 475 is controlled over the GPIB by the Hall Measurement software. Are you looking to use the Model 642 and electromagnet outside of the Hall system software for some other application?
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Post by qtsearcher on Jan 21, 2022 16:13:11 GMT -5
Hi, Jeff! Thank you very much for your quick reply. I want to modulate the model 475 power supply, so the output current is a sum of a dc current and a small sine ac current. This modulated current will be applied to the magnet. This ac current will be a reference input to the lock-in amplifier, to lock the signal we detect. Please let me know how we can do this.
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Post by Lake Shore Jeff M on Jan 25, 2022 14:00:15 GMT -5
The best way to do this does not use the model 475. Instead, use the GPIB interface to set the DC level. Then from the lock-in reference out (sine wave) connect to pin 11 and pin 3 of the analog I/O connector.
From the front panel set the external current programming mode to sum. The output current of the 642/643 will the be the sum of the DC level set by GPIB and the lock-in reference on the Analog connector
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