I have not seen the additions you have made on the PDF because the current computer I use gives an error with the file, I will look at it later on a nother computer.

I pretty much understand how the circuits works. I have made a citcuit long time ago that was very similar to what the Bosch ICs are doing. That was with analog circuits right now I am trying to do most of the Analog stuff using a MCU so to minimize tolerance problems and to cheapen things up and also to add dataloggin capabilities to it.

I built my first circuits based on the Bosch Datasheet for the Sensor itself because I never knew the Datasheets for the ICs existed publicly. The circuit I built before knowledge of the Cj120 datsheet was similar in many ways to the CJ120 but more simplier. Now that I seen the CJ120 the only thing I can not understand is on Page 3 or 4 of the CJ120 PDF, the use of Rical (82 ohms). The fact that I can not speak German only adds to the problem. But I am sure somewhere in my subconcious my mind is solving the issue, so it will only be a matter of time before I know what the RiCal does. I suspect it maybe a reference restance that the resistor in the pump Cell (Ri) should be at during normal operations. The reason I say this is becasue I know pretty sure that the Pump resistance should be close to 80 ohms during normal operation and not the 100 ohms that is shown on the diagram.

There is no need to simulate the BOSCH LSU sensor in my testing since I have about 4 of them lying around. Also the Pump current goes through an external 61.9 resistor, I suspect the 100 ohms you are talking bout is the internal resistance of the pump cell.


I would love to by the bosch ICs from rutronik but they require huge quantity purchases something in the thousands per order.

If I can digitize most of the analog circutry I can make a very cheap, fast and accurate Wideband reader.