For comparing my Voltmeters and because of deep interest I build a LT1027 based 5V Reference Voltage Source.
I build it Bird Nest style ( hope this is the right expression) on a single side Copper Board.
The low noise Voltage regulator (LT1763) is mounted on a daughter board.
Daughter board with Voltage Regulator.
First test if it fits in the housing.
Final build but some decoupling capacitors and the input protection diodes still missing.
The finished Refernze in Housing.
Reference in Housing-
First measurements with my 4,5 digit handheld multimeter shows 4.997V
After 30 days of continous running the measurement with a new calibrated 6,5 digit voltmeter shows between 5,00096 and 5,00097V.
The oszilloscope pictures shows the difference between batterie and power supply operation.
All measurements are done with a 1:1 probe with the following settings:
1mV/Div und 2mS/DIV
GND Button pushed.
Reference operated with a linear LM7815 based power supply. Not floating!!
Reference powered with 9V Block batteries.
I have build a 15V power supply with an electronic ripple rejection(it is from an German Electronic Forum) followed by an LM7815.
The result is a line similar to the picture with the batterie operation. No ripple. The line is twice as thick ( hope this is the right expression)
Oscilloscope picture follows…
Rippel rejection German article in ELKO Forum
LT1027 Kondensator Noise Reduktion German thread in Mikrocontroller Forum
Thanks to all supporting thread members.
I put the whole circuit into styrofoam insulated Box and put a PTC-heater foil under the Metal case.
This is the PTC-heater Foil, 12Volt 3Watts. The heater is only controled with it built in PTC. I used a 12 V Switching Power supply for the heater and a linera voltage source for my reference.
Here some measurements at different temperatures:
My thermometer is not calibrated it started at 9° Celsius which is equal to the ambient temperature of 15°Celsius. Hope to get a better one the next days…
Will be continued…