Hi,
Today I want to show how I started measuring 14x the LT1021 in a metal housing.
I can't show all measurement data because I don't have access to it now.
But first let's show some respect for the power supply I've used for almost 5 years of continuous operation to test LT1021 references in two groups.
The first group has resulted in my 10V LAB reference is now still use.
I built this power supply over 5 years ago to gain some experience with pre-regulators to limit the dissipation.
I had to, because I had chosen to build the power supply in one of the old Cisco Pix firewalls housings i had laying around.
The beauty of this housing is that it is very solidly built of thick iron.
As you can see here, I can build three more of these power supplies!
The red push button has a double function, a short pulse turns the output on or off.
If you hold the button down longer, the power supply switches between a maximum of 30mA or 200mA output current.
The reference in this power supply is a VRE310a and the quality of this reference is more than sufficient for this power supply.
I have searched for pictures of the inside of this power supply, but some are erased.
I will check later if I can find anything in one of my backups.
The properties of this power supply are very good and it is also very stable.
However, I am not satisfied with this power supply.
The switching pre-controller radiates into the metal of the box and the box radiates back into the sensitive electronics.
I can't win because it's all too close to each other...
The residue of the Pre-Switcher is approximately 1.5mV under full load.
And these specifications don't fit in with my company profile.
So ... do you want to see the schematic of this power supply?
This is the power supply part together with some switching electronics.
And this is the linear controller, it has two difference amplifiers, one for current measurement
and the other for voltage measurement over the Power MOSFet and the difference signal then goes to the pre-regulator.
And now back to the LT1021 test setup!The power supply is hidden here, so I can't turn it off by accident or change the settings.
It is also visible here that at 15V supply voltage the consumption of the 14x LT1021 references is 10.8mA.
The KeySight E3612A is not used in this setup.
Yes! breadboard, that has proven to be good enough for this test setup.
I used two ways to measure the LT1021 voltage so I didn't have a problem with the breadboard paracitic properties
The 1K resistors at the top connect all LT1021 to each other, so that I also have the average voltage of these 14 units.
The first values are noted...
This is one of the waysi used to measure the outputvoltage of a LT1021,
after installing the measuring clamps I leave the whole thing alone for a while until everything is at the same temperature again for a stable readout.
The list is getting longer...
Three months of drift data.
Be aware of the temperature, humidity and also the drift of the TEK 4050 DMM.
And now some data from a year later, there is more, but i can't show it right now, the notebook is on the other side of the world...
This it it for know!
Kind regards,
Bram