Looking for cheap, weather-proof keypad

Discussion in 'The Projects Forum' started by GS3, Oct 8, 2007.

  1. GS3

    Thread Starter Senior Member

    Sep 21, 2007
    I have a stock of electronic access-control circuits. Basically you connect a 1/n keypad (not matrix) and when you press the correct 4 keys in sequence the thing closes a relay and opens a door or disconnects an alarm or whatever. These circuits are mounted on a base with a metal cover. I have had them for some time and would like to sell them but I have found that most people would want to get a keypad with the circuit. Preferably a weatherproof keypad so it can be mounted outside (it's no use if you mount it indoors, is it?) It needs to be cheap because it will be an addition to a cheap item. I am not going to buy $25 keypads in order to help sell $15 circuits.

    I have been looking around and everything I found is just extremely expensive. Does anyone here have any ideas? Maybe find some surplus keypads or some way to make them cheaply?

    Ideally the characteristics would be:

    -Any number of keys but I suppose 12 (or 16) would make most sense.
    -Readily and easily wall mountable with screws. Not just a keyboard for which you then need to find or make a front plate or enclosure. The idea is for the whole kit to be easily user-installable.
    -Ideally screw connectors for the wires is simplest although I suppose other options might work.
    -Ropen>10Mohm, Rclosed<5Kohm, I suppose traditional mechanical, push-button would work best but other types might also be ok.
    -Reasonably weather-proof. No need for seriously weatherproof which would stand up to wind, tide, flood and "nukular" weapons but that it can be mounted in a reasonably protected outdoor location and last a few years. In my experience mechanical switches mounted outside, even if protected from the rain by a cover, tend to start having problems fairly soon because dust and condensation get into the inner contacts and they soon stop making good contact. I suppose a sealing membrane covering the whole front might do the trick. Or using reed switches but this would get expensive.

    I would need a small quantity of about 150. If we can find some ready-made units that would be great. If we can come up with a clever design maybe I can have them built or get some parts and built them myself.

    As I said, low cost is of the essence. I would say $5 or less.

    As a sidenote I will mention that it seems the keypad ends up costing as much, if not more, than the electronic control circuit and it has made me think that one could build a control system which used, instead of a keypad, just one or two buttons. With one button the user could tap morse code and with two buttons the user could input binary. On the other hand this might be unwieldy. No one expects to have to learn morse code to enter a building. And tapping a long binary code would lead to many mistakes and frustration.

    The advantage of a simple keypad is that you can change the code without need to change the users' key, remotes or whatever. This is useful when you change tenants. You can give many people access to, say, restrooms or other common areas but change the code regularly. Also at home you can have it as a complemet to the remote control for the garage or other access. Then you can use it if you forget the remote or you can give the code to someone who needs to have tempoarary access and then you can change the code.

    ETA: here's a nice sample from Digikey but way to expensive. And here (warning: PDF) is their catalog page with prices. The 3000 series, described as general / sheltered outdoor use is $29. The 2000 type, harsh industrial / wet, is $45 and the prices go up from there. I need to divide the prices by 6 (at least).
  2. thingmaker3

    Retired Moderator

    May 16, 2005