Posts posted by keile
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 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.
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.
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 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
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!
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
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!!!
Check this link for some useful circuit
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!!
Check this out remove the IR parts & place RF communication link it might just work ;D
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
thanks trigger! :)
i have researched on the tone detector IC LM567 and found it.. uhh.. confusing ???
well, i have decided to take a look at my electronics book if I could find anything that would help my project. Phased-Locked Loop interest me. After reading all the explanation in the book plus a tutorial on the net, I found that this what I'm looking for, the PLL!!
Phase-Locked Loop (PLL) is an IC that synchronize two signals and output a voltage proportional to the phase and frequency of the input and self-generated frequency.
PLL IC's come in form of NE566, LM566, NE565 and LM565... I just noticed a similarities... LM567 is also a PLL! hehe.. sorry I'm so dumb to realize it sooner. Thanks again trigger!
I'll be back to post a circuit of my design. :)
hello I'm back! :)
btw, before I continue on.. I would like to give a lotta of thanks for trigger and MP for helping me on this project.. thanks a lot!!
Something strikes me while listening to my instructor bout 555 timer. And this what I think how my circuit should be (below)
and now i think there's a problem.. the two signals might not synchronize each other.. one might be low and one might be high.. i have to ditched the comparator i think..
my goal is to use PWM(pulse width modulation).. so i think the receiver would check the width of the pulse rather than compare it with the (same pulse width)--needs synchronization.. if there's only a way to measure the width of the pulse..
thanks in advance.. actually i'm happy if I could build the circuit by myself.. :)
wow that was quite similar to my project.. anyway I think this is similar to the details you have described:
oh so a higher frequency has lots of difficulty in terms of building a transmitter...
do you have any idea how can i avoid interference if I use a lower frequency like 433Mhz? ???
wow! that's one hell of an amazing device!! honestly, if I look and examine its every detail, its perfect for my project. With its security and features.. wow.. but the 433Mhz chip cost around $54 uhh.. but a whola thanks!!
this is what I have tentatively decided:
minimum of 10m
around 2.45Ghz *same as bluetooth
PM (Pulse Modulation)
uhh.. i still don't have an idea
thanks! ill update to find more circuits :)
Our project has been approved and now we need to build our prototype.
As I research, our project is basically a radio controlled device. Push a button in the transmitter side and when it was received by the receiver it buzz or light.
I know it is quite simple compared to examples shown in sites. ???
Now I don't know how and where to get started. I'm thinking of using pulse modulation to send commands. Command to light or sound.
Thanks in advance ;)
Note: I'm fairly new in practical electronics. As I have already studied
theories.. I think I can learn well.
thanks for the reply ^^
wow.. very nice and helpful page! thanks!!
uhh.. you think so? umm.. maybe.. oh well.. i have think about this, hehe, why not just bring a timer and use it while calling on the phone? i'm dumb :)
i'm thinking of a device that would time a call that is separate from the phone.
It might use a LCD to display the call time. And I'm thinking of using a Cellular Phone calling detector to detect if a call is still in progress.
Its main application will be to inform the caller(user) if how long he has been on the phone.
Any insight would be much appreciated :)
ohhh.. so chic seaker means charm seeker!
oh that's nice.. i might choose that as our title :)
'Sheik'? what's that?
Well, I thought 'Chic Seaker' is a finder of chics :)
remote control using radio freq
in Electronic Projects Design/Ideas
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 :(