Schematics of delabs

One of the oldest Schematic Archives on the Web. It was in the form of pdf files in the late 90s. Instrumentation and Industrial Designs by delabs and Generic Application Designs.

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Wednesday, March 15, 2017

Millivolt Milliamp Source - Field Calibration Current Loop

This is easy to rig millivolt source for field calibration or troubleshooting of 4-20 mA current loops. Here a Darlington pair is used for current amplification which reduces the Ib error as gain is very high.

EE Design Library - Electronic Product Design Resource.

Millivolt Source - Field Callibration Current Loop

A rotary switch selects, 4-12-20 mA Preset points. A Bourns multi-turn wirewound Pot can also be used with a digital dial. Enclose in a dust proof handheld box. Read more on process calibration.

A mA source terminated with a 10 Ohm or 100 Ohm can turn it into a mV Source. The Resistor should be above 1W and has good temperature stability. Use MFR 1 % many in parallel to get a Instrument shunt if you do not get any.

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