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boot

Potis at the AIN

4 posts in this topic

Hi.

I have two relative easy questions:

First I built an array of potis like it is described in the documentation. My question is now: Since all potis are arranged in parallel order the resistance of the 10kOhm potis doesnt vary linear like they do when measured a single one (this comes from the rule of resistance behaviour when resistors are arranged parallel). My question is now if the software considers this. I mean the range and the behaviour of each poti is very sensitive to the number of potis used. Does the software recalculate this into MIDI signals by knowing the number of potis?

Second: I bought potis with a center detent. Unfortunately I recognized that in this detent the resistance values vary from 4.7 up to 4.9 kOhm. The question is now how sensitive or how big the resolution of the AIN is. Am i getting problems using them as EQs?

Best regrads

boot

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the resistors are only acting as voltage dividers. they are just all hooked to the same +V and GND. to have resistances all parallel it would be necessary to also join all wiper pins together, which is not the case. so there shouldn't be interaction between the pots if everything's installed correctly.

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hmm I was quite surprised when I remeasured the potis with a multimeter and the values between the "wipe pin" (in the poti schematic the one in the middle) and the other two have changed drastically. Is this normal? I have additionally added a sketch of my setup. The four parts at the top are some potis. The middle pin is thought to be connected to the AIN.

post-6896-0-03545600-1310550489_thumb.jp

Edited by boot

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Say your pot has three tags. The one in the middle is the 'wiper'. If you set the knob to the middle of its travel, then measure between one tag and the middle one (the wiper) you will get a resistance. Now measure between the wiper and the other tag, you will get another resistance. If the pot is linear, both will be about the same. If the pot is a 'log' pot one will be much larger than the other. This is because log pots are often used for volume control, so that the apparent increase in sound level matches the response of the human ear.

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