Hello, we are new to this site. A bit about us: We have had ferrets for about 3.5 years. We had one that tragically died a few months ago, and we had just rescued 2 ferrets that are sisters. They are about 3-4 years old. Our old ferret (Weasley) we had trained to come to a bell when it was night-night time. We let them out for free run of the house during the day, and caged at night. The 2 new ones, as all ferrets are excellent at hiding in the craziest places. Since our grandkids live with us (3 and 8 w/Down's), it's impossible to keep all the doors shut (even though we live in a smaller 2BR appt). Has anyone heard of a collar with a little chip or something that allows a ferret to wear with a small transmitter that a hand-held device could send a signal that would beep the collar so that it would be easier to find them? (Like find a phone on a cordless phone). Bells are nice but only if they are active. Any ideas?

I have seen such things, but I'm not sure where.  Try sharperimage or just look on amazon/ebay.  The problem I see is getting the ferrets to keep a harness on, lol.

Here ya go

http://www.sharperimage.com/si/view/product/Lost+Item+Locator+%283-Pack%29/204012?question=locator

Welcome to the group

THE DOOKS OF HAZARD

When you have your ferrets out with the kids around.  Can you gate off a room for just the ferrets.  This way, you will know that they are safe in one room.  They won't be escape out a door way.  Putting beds around, makes it much easier to find them.

I hope this helps and good luck

NOt sure about the transmitter collar we used bells on the collar. You are right only helps when they move but at least you hear the movement and may know where to start looking for them.
I would work on training them to come to the squeaky toy/bell like your old fuzzy. Squeak then treat, repeat, repeat, repeat. They should get the idea and should be easier to locate. We had our Pirate trained to come to the squeak toy, Captain and Morgan started coming to it too but not 100% of the time but the noise intrigued them and getting a treat only helped reinforce it

good luck