Round Dial, Electronic Combination Lock

[Pic_User]

The beginning Idea:
Electronic "Combination Lock".

Not the typical, keypad, or the push-button type.
More like , the round dial mechanical type.
Instead of a real mechanical dial, use a multi-turn potentiometer ("pot"), with a "turns counter".

The push-button type is better suited for alarms, garage doors etc..
The round mechanical dial, multi-turn potentiometer might be used for places without enough room for the keypad.

Most interesting, is the "retro look".
The turns-counter, looks like a typical combo-lock on a "safe" or vault.
The external foot-print would be smaller than a keypad.

The code:
Some of the code would be identical to the "resistor string", voltage divider style.
Where the A/D voltage, of a voltage divider, tells the microcontroller, which button is pressed.
This, would be a rotary dial, with a potentiometer (voltage divider), instead of a resistor string (voltage divider).
Same principle, except; minor mechanical "set-point" errors, would look like wider "tolerances".

I would like to get some ideas:

What types of algorithm do you suggest?:
How to make the lock field programmable.
Make the combination changeable.
How to allow for the mechanical accuracy (tolerance).
To tell the PIC that the operator is still turning the pot, hunting for the next "set point", or number. Then, when the movement stops for a certain amount of time consider that the "selected" number.

---------------------------------
This is not a needed, "must have" project.
More like, a fun "what if", thought experiment.

Why:
I have some fancy, 10 turn, potentiometers.
These are Bourns', "Knobpots®", with a turn's counter, dial built in.
There is a mechanical, 0 - 500 dial, like an odometer.
There are 4 markings (tick marks) between each of the 500 digits.

10-Turn Precision Potentiometer
3610S-1-103 Part number
10,000 Ohms Resistance
Min: 10 Ohm Resistance
Tolerance:+/- 5 %
0.022% Resolution
3600 ° nominal Rotation (10 turn)
http://www.picbasic.co.uk/forum/atta...1&d=1151969122

http://www.bourns.com/pdfs/3610.pdf

http://www.mouser.com/catalog/626/503.pdf

These Knobpots, are very retro looking, small, and unique.

Any pot, with a turn's counting mechanism, should work as well.

Your ideas are welcome:
What would be a good place to use either, the rotary or the button lock?

Other uses for these Knobpots.

Any thoughts you might have, on this general topic.

-Adam-

[Darrel Taylor]

Shouldn't be too hard to make a Combination lock out of that. But, given a 3 number combination, with a 10-turn pot, I'm thinking your wrist is going to get pretty tired of turning.

Perhaps a Left-Right-Left (similar to Master combination locks) single turn, with a quadrature encoder instead of a pot. Or even a single turn pot, if it's continuous (full 360° resistance).

.

[BobK]

Hello,

Nuts & Volts magazine ran an article several years ago about a dial type combination lock. I lloked at their FTP library and all I could find was a program called DIGI-LOCK in the October 2005 issue. I'll look thru some of my older NV issues tomorrow and see if I can find anything. I think a guy who worked for ADT designed it.

BobK

The program is for the Basic Stamp 2 but is suppose to easy to convert to PBP.

[Ron Marcus]

How about a rotary encoder, with a generator attached. You give the dial a few turns to charge a big cap, then do the combo. You can eliminate the battery that way.

Ron

[Acetronics2]

Hi,

The Elektor magazine published some times ago a "serial Digilock" ... just use an old "black" ebonite phone to get the number to pulses conversion !!!

Perfect for the " retro look " !!!

for realism, the simplest rotary encoder wil fit, better if clicks are "sound enhanced" !!! ... just use a D Flip-Flop gating to authorize the " once left, once right" operation !!! ... or keep direction info for safety !!!

Alain

I look for project N° ... got it : 040481, July/August 2005 release ...

[mister_e]

LMAO! i did something using the old vintage wall-mount telephone like that here at home few years ago... it replace the usual Home Alarm Keypad.

EDIT: Thanks for the reference Alain. Sometimes those 'maudit francais' are usefull ROFL!