Ulf's Adapter - Question about the trimmers in the circuit diagram

Hello everyone,
I have one or two questions about the trimmer potentiometers in the schematic diagram for Ulf's WorstCase 4.0... To preface, I am not an electronics expert, just a curious amateur.

If I assume that the flow direction of RS232 is from VR1 to OK1 (I hope this is correct, but my following assumption should also apply for the reverse case), I wonder what the lower leg of the trimmer potentiometer is connected to.

Assuming that a current always seeks the path of least resistance, it flows from R1 into the "input" of the trimmer and then through the tap to pin 1 of OK1, and from there, via pin 2, back towards pin 2 of OK2. However, pin 2 of both OK1 and OK2 is also directly connected to the "output" of VR1, which always presents a resistance of 10k ohms. The path through the output and OK1 will always have (*assuming a 0-ohm resistor for OK1 and that the trimmer is not set to its maximum value*) a lower resistance than the other path.

Could we not actually do away with the connection for the "waste"?

Regarding VR2, I'd rather refrain from making any wild speculations.

I'm having the same problem with VR4 (which is probably actually VR3, right?). What's the purpose of the direct connection between pin 2 of OK3 and the third leg of the trimmer? Couldn't we just connect pin 2 directly to R14?

I hope you don't immediately jump down my throat because I don't understand some of the basic concepts of electrical engineering... it's very possible that this is all a bit too advanced for me, so please enlighten me.

Thank you!!!

Tino Kossmann wrote:

For example, if I assume that the flow direction of RS232 is from VR1 to OK1... I wonder what the lower leg connected to the trimmer is for. Bitte gib mir den deutschen Text, den du übersetzt haben möchtest. I'm having the same problem with VR4 (which is probably actually VR3, right?). What's the purpose of the direct connection between pin 2 of OK3 and the third leg of the trimmer? Couldn't we just connect pin 2 directly to R14? I hope you don't immediately tear me down because I don't understand some of the basic things in electrical engineering... it is very likely that this is all a bit too advanced for me, so please enlighten me.

Hi Tino,

In a nutshell:
The potentiometer circuit (as designed in the schematic) has the advantage over a simple series resistor (= your idea) that you can completely reduce the current flowing into the OK inputs down to zero .
So, an expansion of the adjustment range, which is generally beneficial.

More in-depth explanations would be out of place here - the basic principles of electronics are actually not the topic of this forum.