Possable to automate keypad input?

[demir57]

I have an old scanner that does not scan, the frequency's must be typed in manually. Is there a circuit that I can use to type in the numbers automatically? the frequency ranges are 30-54, 138-174, 380-512. the frequency format is "123.455". the scanner model is realistic pro-58 scanning receiver 20-400.
the scanner automatically ignores wrong input frequency's. if you know of any other modifications i can make to this particular model of scanner that would be great as well.

thanks
demir57

 

[kchriste]

Maybe try and fix the scan circuitry? Is the squelch circuit functioning properly?

 

[demir57]

It was never designed to scan. I read the manual it only takes manual input.

 

[kjennejohn]

Way back when printers weren't available to the general public (and people had to program personal computers using switches on a front panel) I saw one man's solution using an IBM Selectric typewriter. He made a framework containing banks of solenoids with rubber plungers on them. Each solenoid/plunger was aimed at a key on the Selectric. He used a matrix of wires from a unique control card of his own design to determine which solenoid got fired to strike a key. It was ungainly and weird, but it worked. He would feed in a sheet of paper and have this contraption print out a page of preenterd text.

So, build a frame, populate it with solenoids with soft plungers, and have a PIC determine which ones to fire at the keypad based on a predefined list of frequencies. Small embedded processor boards can be had for less than a $100 for the controller. The frame and the solenoids sound like the tricky part.

Later!
kenjj

 

[demir57]

The solenoid idea got me thinking. I could use 3 cd4066 IC's connected to the switch contacts. I just have no idea how to build the circuit to count up and down. I need to be able to have it scan automatically and be able to stop it and go up and down incrementally.

 

[Super_voip]

The scanner keyboard will have contacts under the buttons, usually bridged by conductive surface on the underside of the keypad. If you aren't concerned about the appearence of the scanner, the keypad can be left off. I know someone who did excatly this hack 15years ago, back then he used the parallel port to control the switches. Given the scarcity of parallel ports these days, a PIC solution may be the easier. I think I also have a Pro 58, the only mod I made was to extend ??? (can't remember) to the outside so I could use the signal to drive a homemade deviation meter.

 

[demir57]

What type of PIC would i use to drive 3 cd4066 ? There is plenty of room inside the case to put the circuit in and just integrate to the keypad contacts underneath. I don't have any experience with PIC's, i have some experience programming, but i love to learn and play with new toys. I have several old computers to try the parallel port method as well. but i would like the unit to be somewhat portable.

thanks
demir57

 

[kchriste]

What type of PIC would i use to drive 3 cd4066 ?

Any PIC that has enough IO pins for what you want to do. Since 3 4066s would equal 12 IO pins then the common 16F628A would work fine for this.
You may be able to eliminate the 4066's all together if you can figure out how the keyboard is multiplexed. It may be a 3 x 4 matrix with the rows being outputs from the scanners MPU and the columns being inputs to the MPU. You would configure the PIC to detect the scanning pulses from the row circuitry and output the correct logic levels on the column circuitry to enter the frequency needed. This would make the PIC software a little more complex, but you'd eliminate a lot of extra wiring and would save 5 IO pins.