keile

Greetings! I wanted to take this time to thank everyone for sharing their time and knowledge to make this project possible. At last, we passed our design project. The only downside is that we had used infrared instead of radio frequency to give us more time to focus on the encoding and decoding section of the project. Now that I have more time available, I'm planning to continue our original project. The time we spent on building the project had given me lots of knowledge on the electronics world.. heheh.. I really mean, I really learned a lot! By the way, if you're interested here is the schematic for the transmitter and receiver section. Note that it uses infrared as a wireless links :(

thanks a million audioguru!! just what i needed :)

what is the radio frequency that is available for use with any electronic devices without the need for a license? after researching this is what i found: 40 Mhz - garage door, alarm system 40-50 Mhz - standard cordless phones 49 Mhz - baby monitors 27 & 49 Mhz - basic consumers items i'm building a project similar to a keys finder.. is it alright if i use 49 Mhz? where could i find any document regarding the use of radio frequencies? Thanks!!

hello! thanks Chester for some thought :) yeah.. maybe there's some step-up ic inside .. coz the device also light a red LED to indicate if there's a signal (i know LED doesn't work on 1.5v). it's around 10 days before our defense and i hope we can get the circuits fully working as soonest possible time. wish us luck.. thanks everyone! :)

i opened my father's wireless microphone receiver and it contained an TDA70** ic (sorry i forgot what number)... and it only runs on AAA size 1.5V battery.

to audioguru: uhh sorry.. actually i just want this thread to focus on transmitter thing.. and to ask all about its variations.. i have researched lots of transmitters already and always wondered why it differed in many ways.. wow.. i didn't know that the capacitor has a value of 5 to 40pF.. sorry i don't know how to distinguish different types of capacitor. to MP: yes.. when i'd seen the circuit i think that it is what my project should be.. though there are some components i didn't understand like the varactor diode and the JFETs... so u know, i can't use it in my project until I understand what those components do. btw, thanks for the help.. i really appreciate it :)

yeah.. hopefully we can make a fully working prototype by next week.. I checked TDA7000 and TDA7088 IC's and looks like they're a complete fm receiver with no amp.. and I assume MC3361 and MC3362 is the amp right? I wanted to run my receiver with 1.5V battery to reduce weight and I think these components would serve my needs.. As always, many thanks to trigger for your continuous support and help for my design project. May god bless you on your way :) thanks, keile

thanks a lot for explanation audioguru! actually for the mic i wanted to replace it with a 555 timer to generate tone so an amp might not be needed? also, the trimmer capacitor has no value.. i don't know.. maybe it is just optional.. btw, i got the schematic at this site: http://tacashi.tripod.com/elctrncs/smplfmtr/smplfmtr.htm

hello! i got a very simple fm transmitter yet very stable, low power and have reasonable range (the author claims) i'm having a problem to get it working.. :( I don't know if the 28pF capacitor which is connected to the collector has something to do with the parallel resonant circuit. Also, what's the use of 2pF to connect the antenna? Hopefully someone here have good knowledge bout transmitters.. Thanks a lot! keile

try 555 timer configured as monostable.. components resistors and capacitors determine the time..

try this simple FM transmitter that could transmit at a max distance of 50m with only 3v supply http://tacashi.tripod.com/elctrncs/smplfmtr/smplfmtr.htm

hello! so far this is the flow of my circuit: 555 timer(information,encoder) -> fm transmitter(carrier, modulator) ~~~ ~~~ fm receiver(demodulator) -> PLL (decoder) -> output i'm now in the process of testing transmitters and receivers.. i' ve come across this very nice fm transmitter: http://tacashi.tripod.com/elctrncs/smplfmtr/smplfmtr.htm i'm planning to supply my transmitter and its receiver at 3 volts. is there any 3v fm receiver that is simple enough for my project? Thanks!!!

wow! trigger I can't believe it!! You actually found it! :) oh thanks a lot!! it's so similar that it only needs few customization or maybe not? hehe.. thanks again!!

thanks.. i'll check it :)

wow that's so cool!! how about drop a handful of black colored rounded object? heheh.. seems like a war zone :P