Hi all! I would like to introduce one project I was working on for a pretty long time. Now in late development stage but soon I will present it on some crowd funding site. It is very special resistance substitution box (device) that can be useful for prototyping on breadboard, fast circuit board debugging and teaching. It consists of four potentiometers that can be easily replaced by the user. There are no limitations - the user can mount multi-turn pots, stereo pots, mono pots of different resistance rating. By using mono (single) potentiometers the principle is easy - when user wants to set some resistance, he just flips a switch that will connect the potentiometer to measurement circuit of the device and he is informed about set resistance via LCD display.
After the value is set, you can flip the switch again and the potentiometer will be connected to the output connector. The value will be still indicated. Leads are inserted into breadboard where they behave like you inserted resistor instead. It is a matter of seconds to change its resistance by the same procedure.
With stereo(dual) potentiometer you have one significant advantage. Due to the existence of the second gang(track), you can have potentiometer resistance connected to your circuit, change its resistance at the same time and still be informed continuously about resistance value that is set (device measures the resistance of the second gang(track) and after compensation you get the resistance value that is set on primary gang(track)). Compensation is necessary, because the resistance measured on second gang is not exactly value that you will measure on primary gang that is substituting resistance in your circuit (so-called gang error - dual pots arent ideal). But with calibration procedure that this device is capable, the value measured is compensated and you get value you can trust.
The principle is maybe more obvious on attached picture.
Additional features
- Possibility to save all resistance values to one of the 4 profiles. You can then reload the profile values and manually adjust pots so your circuit that you had connected in past will behave the same way.
Thus you can use this device for several circuits at the same time and you have information on what resistance was set for the circuits before. - Calibration capability for stereo pots (gang error reduction)
- Capability to remove and mount different potentiometers (multiturn, linear, logarithmic) with different values of maximum resistance. Information about the all potentiometers is then displayed below the displayed resistance.
- DFU - device firmware update with the PC and micro USB cable.
- Additional configuration - color schemes, test modes, factory reset etc etc
As an example I've just plugged dual op amp to my breadboard and inserted leads from the device and created relaxation oscillator. Only had to plug capacitor. It was finished after quite a short time and the possibility to change resistance easily of all three resistors in circuit is just awesome.
The accuracy of measurement of resistance is also pretty good. Still improving but for now it is definitely below 1% of resistance value. Tested against calibrated HP multimeter.
What is your opinion? Fill the poll please :-) Thank you!