This is a continuation of the previous two circuits. This circuit controls the temperature in a miniature oven that holds a stable dual voltage reference.
In colder seasons or locations this will maintain the temperature at a higher level. A mini fan in the equipment ensures external heat does not reach the oven, fan keeps the larger chassis cool.
Temperature Measurement and Control
This circuit may fail if the equipment is in very hot open locations, big heaters, hot machines or direct sunlight falls on equipment OR the Lab is not cooled to near normal ambient temperatures.
Electronic Designs, Digital, Analog, Power and Electrical Circuits.
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.

Tuesday, February 26, 2019
High Stability Reference Mirror
LM399 is a Precision Reference chip. From this a dual polarity mirrored reference is derived using OP07 op-amps. This assembly is mounted in a miniature oven to ensure temperature stability.
The oven used Two Steel Boxes one mounted in another with Glass Wool In-between to reduce heater losses. Steel was used to ensure excellent EMI-RFI Shielding. Both the outer and internal shell was earthed.
Instrumentation and Measurement Circuits
Regulated and Filtered Supply to this assembly further ensures consistent performance over the years and in various environments and seasons.
The oven used Two Steel Boxes one mounted in another with Glass Wool In-between to reduce heater losses. Steel was used to ensure excellent EMI-RFI Shielding. Both the outer and internal shell was earthed.
Instrumentation and Measurement Circuits
Regulated and Filtered Supply to this assembly further ensures consistent performance over the years and in various environments and seasons.
Sunday, February 24, 2019
Differential amplifier for HV Power Supply
This is part of a precision High Voltage but Low current Power Supply for Testing leakage currents in passive devices. This Supply is a module for a Automatic Test system in component inspection.
HV Precision Power Supply Circuits
Insulation of Transformers and the Isolation of plastic capacitors are best analyzed by applying a High Voltage and measuring the leakage currents.
These currents are in the order of nano-amps and pico-amps; values close to the bias-currents and leakage currents of devices. Some offsets and corrections can be done in software for the ATE systems.
HV Precision Power Supply Circuits
Insulation of Transformers and the Isolation of plastic capacitors are best analyzed by applying a High Voltage and measuring the leakage currents.
These currents are in the order of nano-amps and pico-amps; values close to the bias-currents and leakage currents of devices. Some offsets and corrections can be done in software for the ATE systems.
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