auto set divider circuit

[wijnendael]

Hi, can anyone give me a clue how the following is obtained.
I have built myself a rudder indicator for my boat that uses a 10K pot as a divider to give me the +/- indication of port and starboard postion on leds. I have to manually trim the pots to set the system up but have recently purchased a piece of kit that will do this automatically by setting the position and then pressing a button. By doing this in the centre and the port and startboard position the unit is set. How do they do this and is it possible to make my circuit do this so it is easier to recalibrate when required. Any information would be greatly appreciated so that i can look into it further.

 

[ericgibbs]

Hi, can anyone give me a clue how the following is obtained.
I have built myself a rudder indicator for my boat that uses a 10K pot as a divider to give me the +/- indication of port and starboard postion on leds. I have to manually trim the pots to set the system up but have recently purchased a piece of kit that will do this automatically by setting the position and then pressing a button. By doing this in the centre and the port and startboard position the unit is set. How do they do this and is it possible to make my circuit do this so it is easier to recalibrate when required. Any information would be greatly appreciated so that i can look into it further.

hi,
You can buy 10K digital pots that have a non volatile memory.

The digi-pot is incremented up/down by a switch or a pulse input.
The pot stores the 'resistance' value count, so when power is applied the digi-pot restores your settings.

Google for Digital Potentiometers

A starting point:
**broken link removed**

 

[wijnendael]

thanks for the reply i will look into the possibilities of this, but the unit i have uses a conventional potentiometer connected to the indicator so they must do something inside the unit to set the led meter

 

[Pommie]

The only way I can see to do this would be with a microcontroller. The fact that the unit can remember the middle, both extremes and calculate the inbetween positions would suggest some modest computing power. This, reading the pot and controlling the LEDs, could easily be done with a 16F88 which is a 16 pin chip that cost around $2.50. It would of course have to be programmed but there are lots of helpful people here if your willing to get your feet wet.

Mike.