Re: Mains powered very low power transmitter - need help please

I read in sci.electronics.design that nina.p20 <nina.p20@xxxxxxxxx> wrote (in <1124179239.032777.239520@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>) about 'Mains powered very low power transmitter - need help please', on Tue, 16 Aug 2005: 
Thank you again Mr. Woodgate for responding,
I'd like to split my question to 2 parts:
First, I'm really interested to understand how those devices are made,
just for my information and knowledge.
Secondly - what I really need is a wireless babysitter, and cheap
one...

Buy one: you couldn't make one for less than the purchase price AND they work in a permitted frequency band as well as being safe.

I've Mentioned this frequency because it's receptable on a domestic
receiver, and the range may be up to 100m. As I have some experience in
electronics, (well, being supervisor for the last 27y of an electronic
lab - not RF - and now retired) I'd like to build such devices. I can
make some changes to the receiver to work at higher frequency, let say
110 - 115 MHz...no problem. The problem is that the devices I've build
so far (as mentioned in my first post) are very unstable, noisy (can
hear the 50Hz ripple louder than the picked sounds). I'm aware that
there will be no chance to get a licence, and about the fire danger -
at the place it's been intended to be placed there is no chance, as
it's a concrete 3m high wall - far away from any dangerous flamable
material
TIA for further help :)
Regards,
Nina

I'm sorry, but your message indicates to me that it would be inadvisable to advise you further. 110-115 MHz is outside the range of broadcast receivers because it is used by aircraft systems, including landing systems, so you would stand a good chance of causing an aircraft crash.

Also, ANY fire is dangerous, even if it's only the electronic equipment that burns up. Burning bits drop on people below.

If you didn't learn discretion in 27 years, I stand no chance of teaching you now.
--
Regards, John Woodgate, OOO - Own Opinions Only.
There are two sides to every question, except
'What is a Moebius strip?'
http://www.jmwa.demon.co.uk Also see http://www.isce.org.uk
.

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