As promised in Circuits & Secrets, I have refined my original DTMF Decoder design to run off a PIC microcontroller. While I was at it, I made many other refinements, including a 510 digit non-volatile serial EEPROM memory. Information is stored forever, or until overwritten. I am considering manufacturing these, but first I'd like to see how well the prototypes sell. I had PC boards professionally burned for these prototypes. Here is a partial list of features:

Direct phone line hookup for unattended monitoring
Space inserted after decoded numbers according to user selectable inter-digit gap time
User selectable inter-digit gap time of: NONE, 4-sec, 8-sec, or 1-minute
User selectable "Ignore" options
 Ignore a '1' when dialed first in a series
 Ignore 1+AREA CODE when dialed first in a series
510 digit memory
Low power mode when memory is full
Will not overwrite memory until user resets or clears log
Tones can be decoded via direct line from ham radio or scanner with optional cable
User's manual explains how to decode tones recorded on tape
No confusing "scroll." Page through memory 16 digits at a time.
Runs off 9-volt battery or 9-volt battery adapter
 

The features are better described here in the manual.
You can also download the manual in PDF format by Clicking (Netscape) or right-clicking (Internet Explorer) here.
 
 

I am just a lone guy, not a huge company so I can't really offer an official warranty. Basically, if I get killed and your decoder dies too, you're out of luck (unless you can follow the schematics I'll soon be publishing). Barring my untimely demise, however, if you have a problem with the decoder, and are willing to ship it to me, I'd be happy to repair it for you. If the fault was mine, I will not charge you. If you (or your dog) threw the gadget in the ocean and then dissected it in a fit of lunacy, well, then, I'd hafta ask you to cough up a sawbuck or so.

The production models, if I decide to run them, will sell for $99. I'll let the prototypes go for $69. They are the same as the production models will be, except the production boards will have a silk-screen layer (to help me place the parts), and a few drill hole resizings, etc.

SUPPORT ITEMS FOR PIC-CONTROLLED DTMF DECODER WITH 510 BYTE MEMORY

I also have support parts available if you'd like to build the circuit yourself. Right now I'm only burning 3 boards at a time so they're expensive -- $22 each. Once I can burn 100 at a time, the cost will drop to around $7.00, but this may never happen. Pre-programmed PIC's are available for $10 each, 8870 chips for $5.00. Printouts of manual, schematic, stuffing diagram, PCB layout for $5.00. The cost is mainly to cover my contact for her time and aggravation (see below). All costs include shipping. The whole support kit (PCB, schematic, stuffing diagram, PIC, 8870, documentation) is $39 until I can reduce my PCB cost. Click here for price table.

If you're interested, a good friend of mine in New England is handling matters for me. You may contact her by clicking here. Be nice to her, she's a class A gal.

Any questions, just email me.

-- Sheldon
 

OTHER SUPPORT ITEMS

Parts list in Excel 97 format
Manual addendum for home brewers
Code for 2x16 LCD
Code for 1x16 (logical 2x8) LCD
 

Part	Total Cost Including Shipping & Handling
PCB	$22
Schematics, PCB patterns, Stuffing Diagram, Code, & other info*	$5
8870 Chip	$5
Pre-programmed PIC Please advise 1x16 or 1x32	$10
All of the above	$39