hello guys,
i need to know please if it is possible to build a small radio transmission with an electret microphone and RF links or else to make it wireless from the microphone to a speaker or earphone ?
if yes i need help please about what exactly i must search for on google, because i tried many ways didn't really find what i am looking for, and what do i have to dig into ?
thanks in advance 
build a small radio transmission with an electret microphone and RF links
http://www.academia.edu/3634015/Design_and_construction_of_a_wireless_microphone_FM_transmitter
Be forewarned, construction & use of such a device may be governed by government and International laws.
Ray
what i tried to search for is : how to build a wireless intercom with an electret microphone , how to build wireless intercom system using electret microphone ... !
what da hack ! i didn't even get close to your results :S lol
ok i searched for that and looked on the schematic, but how can i catch the signal on the receiver part ?!
firashelou:
ok i searched for that and looked on the schematic, but how can i catch the signal on the receiver part ?!
Any old receiver (AM or FM as appropriate)?
aha ok so it's like a small radio station that send fm or am signals and on the other hand you take a radio and search for this signal isn't it ?
firashelou:
aha ok so it's like a small radio station that send fm or am signals and on the other hand you take a radio and search for this signal isn't it ?
Sure. Why not?
Keep it low-power (or don't.)
Either way, everybody else (anybody else) gets to listen in, too.
aha well yea once a friend told me he made a small radio station but i didn't understand back then how he can do that so easily but now after i finished first book, i understood how it works ! not that hard ! but not that easy to design one by yourself there is lots of calculation to get a specific frequency, it's all about inductor, capacitors and resistors
i have one more question :
i need to know please, how can a frequency be coded which means not accessible unless you put a code, like the ones used in the wireless system (walkie talkie) used for security crew for example ?
(i don't have any experience with these professionals walkie talkie, just the toys we used to play with when we were kids )
how can a frequency be coded which means not accessible unless you put a code, like the ones used in the wireless system (walkie talkie) used for security crew for example ?
Specialized electronics are commonly used today:
http://condord.com/transcrypt.asp
http://www.cmlmicro.com/products/Digital_Voice/
In the distant past of the 1970 until trunking was implemented, often the voice would be mixed with an oscillator and the sideband sent. "Duck Quack." Motorola was active in this area for Fire/Police/public service.
Ray
aha so you mean this device catch something when it feels it then it give you a notice and when you enter the code you can hear the voice coming ?
and is that same device exist in the walkie talkie but smaller ?
firashelou:
aha so you mean this device catch something when it feels it then it give you a notice and when you enter the code you can hear the voice coming ?
and is that same device exist in the walkie talkie but smaller ?
My suspections are that the electronics are embedded in a mulit-function chip/module. Here is a commercial example:
But, surely this is overkill for your project? Most of this type of equipment requires an FCC cert and site license or operator license for units with more than just minimum power... In thee US, u licensed transmissions have very specific frequency and power limits:
Ray
mrburnette:
But, surely this is overkill for your project? Most of this type of equipment requires an FCC cert and site license or operator license for units with more than just minimum power... In thee US, u licensed transmissions have very specific frequency and power limits:
Title 47 CFR Part 15 - WikipediaRay
My goal is to try to design and build a wireless voice transmission module that will be functional when i hit a button attached to arduino. The arduino should lunch a relay just to conduct power so i can hear the voice coming from the module, the small electret microphone