Swapping a rotary encoder?

[dog80]

I have this Philips alarm clock:
http://www.vandenborre.be/WEB/images/products/superzoom/philips_aj3551_135895_2.jpg

There are two rotary encoders on the front, one for setting the hour and the other for setting the minutes. The problem with the minutes encoder is that it doesn't have many "notches" and requires too many turns for my liking until it reaches the desired minutes.

I haven't opened it up yet so I have no idea what's inside. But can I simply swap the rotary encoder with a "faster" one? Or maybe is there any way to make the existing one faster?

[Paul Price]

There are different type of rotary encodes some with more than double the cheaper detents per revolution, good luck in finding one that exactly matches the mounting and shaft dimensions.

If you have the time and MCU programming finesse, hack it, put in your own custom controls to set alarm and clock time or to emulate the pulse train output of the existing rotary encode. It only uses two wires to determine direction and "notch."

You can emulate the waveform feeding into the existing MCU.  To set, the pulse trains requirements are that the first train of on/off transitions either lead or lag the second sequence of pulses so as to determine direction and "notches."

Just compose your own "acceleration" algorithm to advance by x10 or x20 secs/mins/hrs, etc and determined by speed of rotation by your hand.

[jeroen74]

I have that same alarm clock! and I HATE it! It's full of bugs that basically makes it useless for its basic function, waking you up. It looks nice though. I gave it one simply job (and bought another cheap alarm clock to wake me up)... play music all the time very softly and even that it does not very as it randomly turns off it radio; sometimes a couple of times per day, but sometimes it plays weeks without any problem. Definitely a good candidate for Dave's ' bad production design' videos!

The knobs haves enough detents, it's just the software debounce filter that keeps you from adjusting the time any quicker.

[dog80]

An update:

I eventually opened it up and used my waveform generator to simulate the pulses from the encoder. Turns out there is a limit on how fast the numbers can change. A rotary encoder with 24 notches (instead of the original 12) would be probably the limit. Any faster than that and the numbers actually slow down.