looking for a PIC

[dhouston]

As a very different suggestion have you looked at the Si4010 by siliconlabs ?

It would also need FCC approval which is far too costly.

[Demon]

I'm curious, using a different micro would not require FCC approval?

Robert

[languer]

We've tried the following with some "limited" success before as arguments for FCC: "Simple component change for obsolescence retains equivalent functionality does not require re-testing". It seems you're trying a similar approach; however, the FCC will ultimately decide what is acceptable or not (which will be expensive regardless). So if you're making the "call" whether or not to inform the FCC about the change; then the following two are equivalent (we've used them with equal degree of "success"):
-> Replacing a component with and equivalent component as long as the clocks used and/or generated by the two do not change.
-> Replacing a component with an equivalent daughter card (component built-in into a small PCB to provide proper pinout and voltage conversion) as long as the clocks used and/or generated by the two do not change.

And yes I do agree with Robert, using a different MCU could likely require approval - since the method they generate the internal clocks are likely to be different. But I again, it would be your "call" whether or not to inform the agency.

[dhouston]

Well, if it happens it will involve about 50 total keyfobs (at least, initially) that will be deployed in a mountain valley (in the Flagstaff area) where cell phones are useless. Given the terrain and the fact that they will be activated only in a medical emergency, I doubt there will be any significant interference issues but the potential for FCC problems is one more thing to consider. They have introduced one new condition that may force me to withdraw anyway.

I had a radiotelephone license about 50 years ago when I finished USAF electronics training but never worked in the field and have never done anything that required approval. It sounds as if you are active with current FCC contact but I doubt many people would find it necessary to seek approval for this.

And, yes, it is a 12V battery. Most remotes like this and even wireless doorbells use a high capacity 12V battery.

There is one other possibility. I might be able to provide a replacement MCU (perhaps of the same type) for the receiver/dialer unit. I'll have to borrow one of theirs to see what that would involve.

[Demon]

Keep in mind I know totally nothing about FCC and other certifications (but want to learn since it will eventually concern me).

What if you use low voltage micros on a new PCB, does that do a difference? I figure the FCC is mainly concerned with interference with other devices, so what if you kept broadcast power down to a minimum. The device is only used around the house right? Or are you expected to have a 300foot range around the house?

Robert

[dhouston]

Keep in mind I know totally nothing about FCC and other certifications

I already knew that. I was responding to languer.

Read the FCC Part 15 Regulations. They spell out in great detail what is acceptable along with test procedures. A friend with more recent experience as a radio engineer tells me enforcement has been very lax for the past 15-20 years as budget cuts have left them with fewer people.

[languer]

For unintentional radiators you want to try and shove yourself (I think) into "§15.103: Exempted devices". In my experience we mostly work with "digital device utilized exclusively in any transportation vehicle including motor vehicles and aircraft". However, the "certificate of conformity" comes in the form of a slew of regulatory tests not required for FCC, but required for a different agency.

Looks like the stuff you're doing is not commercial (i.e. you're not making money or commercializing it), and may perhaps fall under "§15.23: Home-built devices" if you claim that each one you modify is unique in of by itself.

I have not worked creating part-15 devices outside my normal work (where we normally are exempt because of all the additional regulatory testing done anyways); but I'm always interested in hearing how other people approach it.

Link to a USB hub declaration of conformity example: http://cache-www.belkin.com/support/dl/f5u111.pdf

A couple of useful links:
http://www.arrl.org/part-15-radio-frequency-devices (look into the Verification section)
http://www.part15.us/ (a place for questions)
http://transition.fcc.gov/Bureaus/En...2/oet62rev.pdf (short brief from FCC)