Hi everyone,

I really know nothing about electronics and need some help. You guys come highly recommended.

I need to produce a device which increments a digital display as you turn a dial such as a volume control.

ie From any point on the dial - set Zero and then display say 1 to 100 + with each turn. (3 turns = 300 in the display) but could be any number.

Should be able to show both positive (Clockwise) and negative numbers (Anticlockwise turns) but that is nice - not essential.

Simpler smaller and cheaper - the better - has anyone any ideas.

Any dial device that I can attach to the other dial will do.

Help would be much appreciated.

Steve.

 

Does the dial have to control something other than the display?

 

An optical encoder physically resembles a pot but closes the circuit N times per rotation of the shaft. The encoders I use generate 128 "clicks" per shaft, but I would guess that there must exist some that generate 100 or so. Most of the encoders only generate pulses as the shaft is turned past each detent. There are some that tell you absolute position, though I have never used those. In any case, you should be able to take the encoder input to a simple microcontroller and have the software determine the current value to show on the display. If you are using 7 segment displays, you can scan them quickly save some hardware.

 

On our radio is a dial for volume(its not a potencimeter).It goes very smoth.But it dosent efect the volume is you thurn it wean the readio is off.

You need some thing like this right?

 

thanks for the replies.

I'll explain in more detail what I'm trying to do.

I have a dial which can turn a number of times in either direction (3 rotations each way max). The dial/dials are simple knobs but have no markings for the position they are in. They are on a mechanical device.

I need to be able to attach something to the dial so that when the dial is turned in either direction - a display indicates a number +/- which I could record and therefore return to at a later date. The number of points per turn doesn't matter as long as its at least 60 and less than 200?

I can anchor the counter and attach a shaft to the top of the dial.

Hope this helps.

 

pleeeeeease. ?

Turn a dial - increment/decrement a counter display ? Is this really a problem?

Pretty please!!!

 

It is not much of a problem, but nobody here know what type of device you have that can turn 3 times in either direction. Is there a part number on it, do you have a datasheet, is it a pot, is it an encoder? If nothing else, post a picture of it, maybe somebody will recognize it. The solution is different depending on what you have.

 

Hi Crust,

I must not have explained the problem very well so here goes.

I have an optical device that is used by a number of people. The device is focused by turning a mechanical knob/turret. The knob can turn about three times in each direction from a central point.

Each person tends to use the device at a different setting and I want produce something that I can attach to the dial so that it turns as the dial turns, and increment or decrement a digital counter so that I can repeat the setting for a particular user.

eg The counter would start at zero and count up or down 60 or more for each revolution . The final setting to be displayed on a small digital readout.

Basically I want something that counts up/down as a shaft of some sort is rotated. I can the fix the shaft to the optical dial.

I need some idea of how to go about producing this and appreciate your help.

 

Ok, if you can attach an optical encoder to your system, you can use a very simple circuit that increments or decrements the pulses output by the encoder. Then you can just output the current value on the display.
The encoders that I am thinking of resemble a potentiometer and usually have two quadrature outputs so you can determine direction of rotation and the speed. You can take this data into a small microcontroller and then just use software to figure out the current position and output that to a display. There is probably a way to do this with discrete logic, but in this case, the micro is fewer parts.

 

The simplest approach I can think of is to use a turns counting dial. These are normally attached to multi-turn potentiometers to count the position of the pot. With the right sized shaft it can be used in any other device.

Bourns makes them for their line of pots.

http://www.bourns.com/2/comp_5.html

__________________
"Having to do with Motion Control"

 

Motion,

had a look at turns counting dials - they are just whats required.

Thanks everyone for your help and suggestions.