So OT you wont believe...

[Vincent Volta]

Hey,
As you already know, there are all sorts of stupid applications for small electronics that we'll probably never come across being pedal hackers, but...there are some exceptions.
What I need is a "baby call" device to use with my kid, but a new one is so highly priced it's impossible for me to buy. The thing is a wireless transmitter- receiver much like a fixed walkie talkie. The main problem is that it needs to be wireless, but I think it should be dead easy if you get a schem. Walkie talkies as I mentioned are also useful as long as you eliminate the switch. Well, if any of you has a clue... thanks a lot!

[Transmogrifox]

Sorry I don't have any schematics, but..

Have you tried poking around DIY ham radio pages?  Also, it probably needs to operate at around a 900 MHz range so that you can use a reasonable sized antenna without burning batteries quickly.  Start looking around thrift stores for old cordless telephones and see if you can cannibalize one for the transmitter/receiver functions.

[petemoore]

Walkie Talkies as you mentioned would do the trick I would think, just tape down the transmit button on the one in the baby's room, 'next to the baby.
 There are the AC Carrier types ..the signal is carried by the AC in your wall plugs...plug in anywhere in the house.
 SOmeone around here was doing some wireless hookups IIRC [Smoguzbenjamin?], potsed a while back "officially Wireless', With a decent Mic and DIY transmitter I think you could get a decent tone, and use an FM radio for signal pickup/amplification.

[Eric H]

Walkie Talkies as you mentioned would do the trick I would think, just tape down the transmit button on the one in the baby's room, 'next to the baby.

Beat me to it, Pete. I've seen these in toy stores very cheap.
Baby-stuff is frequently overpriced, and, there are frequently alternatives.

Off-off-topic:
Ever notice that the price of major brands of disposable-diapers (and formula) is usually identical (or very close)? Can you say collusion

-Eric

[Vincent Volta]

Hey,
Since I last wrote I found a page with a wireless microphone kit that seems simple to build. As someone said walkie talkies are cheap and are worth trying too. Thanx to all of you, the page I mentioned is www.electronickits.com if I remember well. The projects are presented in pdf format for further simplicity. Cheers!

[travissk]

I'm not sure how baby monitors work in terms of user interface features (2-way talking? video ?), but I agree the cheapest way is probably to get a set of walkie-talkies for cheap and duct tape the button on one end down, or even just short it/make it latch.

I would also recommend modding it for use with a wall wart power supply, or else battery costs will get to you.


That mic kit has the advantage that you can listen from multiple rooms simultaneously if the transmitter is powerful enough. You can build a wireless mic for cheaper though, but the kit looks like it has a nice case and is convenient.

The only concern I have with the walkie talkies is that the cheaper ones you might find in the toys section at a Wal-Mart or Target may or may not pick up sounds from 4-5+ feet away. I don't see why they wouldn't, but there's always the possibility, and it's worth considering for such an important application.

[Paul Perry (Frostwave)]

I don't know how tight your budget is, but there are over 20 models under $50 new. So it should be possible to get one for half this via a recycle store, I would think. I see them in thrifts, but rarely both halves, though some early units tune via a FM radio (modern units are 900MHz).

[casey]

last i saw, radio shack carried a wireless transmitter kit.

it's just a raw circuit board and it's powered by an "n" type battery.

you can tune it to any fm radio up to 200 feet away.  that way,
you find an open station and you can have multiple 'receivers'
in different rooms.

[gez]

Paul, I tried your walkie-talkie Theramin trick the other day with my 5 year old nephew's rig.  Loads of fun, but I'm not too sure his parents appreciate the new trick he's learnt!