Hi,
Thanks for the remarks.
Most of the ovens i make, are small like the other topic on this forum.
https://www.eevblog.com/forum/projects/small-oven-for-2x-lt1236-%28python-reference%29-no1/The small ovens almost never need capacitief compensation in the loop, this is because the good coupling between the power source and the sensor.
Also becouse there is only a little thermal mass.
JohnnyBergWhen the TI REF5050 came out, i played with the temp output, but you have to use a smal thermal mass and good coupling between the REF50550/REF5010 and the heather.
Someting like a TO220 transistor.
Cut of the thick wires of the TO220 housing, and use thin wires.
Do not mount the TO220 connections on a print, you wil lose so mutch energie and it wil be inposible to get is stable :-)
This is one of the controlers i designed, and i like the most, simple and good controle over the setting.
R1 in the schematic controles the temperature and R3 sets the gain, the do not interact like most of the schematics you see.
Use max. gain as posible, without oscilation.
R4 and R5 keeps the output relatively in the middle of the commonmode range of the INA125.
If you want to use a transistor for the FET, no problemo, just change R4 and R5.
And if you dont like the BPR10 resistor, kick it out, and use only the transistor as the heath source.
I use about 10x the
power as Max to setup the current limit at normal LAB temeprature.
I am not designing for military use, in my LAB its between 18C in the winter and 30C in the summer.
Some pictures of oven design...
This is a piece of ALU tube, the wall is 5MM and you can see a small hole wherethe NTC fitted in, not tested yet.
This is a bad way to do it, a small sheetmetal box...
This is a project i stil have to finnish, a 1Khz AC reference, yes, in the middle a LT1021 as a DC reference.
On the right the LM10 oven controller and on the left you can se a small ceramic TCXO for the 1Khz reference generator.
On the left en right site of the LT1021 you can see a PT1000 sensor for controling the temperature of the oven.
It is al mounted on a big sister of the BPR10 resistor.
On the other site is the control circuit for making 1Khz 1V 0.01% and the distortion in below 0.001%, the 1 Khz wil be within 1PPM.
Maybe this week i finnish this setup of a oven, i uses 4 powerfets to distribute the heat for the oven.
I hope that is wil not be a 0.1Hz oscilator
The black and the white twisted wires are both 5K NTC resistors for controling the oven.
This alu tube is 4mm thick and on top is a thin layer of FR4 mounted.
This are the last ones i show today, smal thick wall alu box.
The design is such that it there is no setting for the temperature.
It wil be whitin 41 tot 44C by design, sweetspot around 42C.
Im made a tester, to test the temp sersor before mounting it in the box.
You can see the sensor in the middle bonded to the aluminum.
This is stil a design in progres, and maybe i wil sell is as a product.
HysteresisI know, for my own use, i select the parts.
This week i received more LT1236A references and i am testing these.
It is difficult to see the hysteresis on a 34461a and i want to ask Andreas how he is using the 3458A DMM.
I have a measuring computer W7 USB-GPIB of HP and a PCI HP GPIB card a modern one.
In the Agilent IO, i can talk to the 3458a, simple commands...
I also installed IZGPIB on this system, but i have yet to learn the command structure.
So Andreas can you kick me in the wright direction so I can make pretty graphs with the 3458a?
If the output is a .cvs, then i am happy Excel wil do the rest.
Kind regarts and thanks,
Bram
sorry for the many grammatical mistakes, strong headache today...