The full scheme is on the way )))
This happened
)))
I finished it
))
Here is a fully working model of the Fluke 732a oven.
You can look at the resistance of the thermistor connected to the front terminals of the device.
Also the temperatures of the furnace itself and the printed circuit board and all other signals
)) For example, turning on the power (last picture)
Model limitations:
1. Two elements were added that were not included in the standard LTSpice package:
- LM358 (model included but you may have to connect it yourself)
- Current Limiting Diode (model attached and included in the diagram)
2. I didn’t have models for many elements. I installed similar ones. Therefore, subtle nuances of behavior may be incorrect. For example, germanium diodes were replaced with silicon schottky ones.
3. The thermal model of the oven must be close to reality and based on calculations. But there are a lot of simplifications in it. For example, the heating of the board itself was calculated through the air from the bottom of the box. Other heat transfer routes are not taken into account.
4. The result coincides with those measured on a live device
5. The circuit is taken from a later edition without transistor Q14 on board A4.
Conclusions from the model.
As you can see, at startup the iron box heats up more than necessary and subsequently gradually lowers the temperature while the board itself warms up. This ensures very smooth heating of the board itself.
If you find any errors or inaccuracies, please let me know
I am often very inattentive.