This instructible is a collection of ideas to make a very low cost walkie talkie
Range can go 1km based on the transmitter selection .
Walkie talkies are easy but the coils IF transformers , matching reciever etc are very boring
.Mainly a usable FM walkie needs three parts
1)tx-rx circuits : we will keep things easy with a 2$ FM reciever, a FM transmitter
2)Squeltch circuit : super cool LDR circuit from tuning LED , childs play !
3)Good battery and antenna : Antenna will look cool , efficiency can be with trial and error
Step 1: The Rx Tx
Rx : is a cheap 2$ radio with a tuning LEd .
digital display will give more cool look , memory of frequency will go costly.but try if you get with station memory.
Transmitter is this one http://jap.hu/electronic/rf/FM_transmitter_100MHz....
Mainly you can use most any FM transmitter
select the ones with
2)compact like say 2cmx4cm
Step 2: The Squeltch
"bzzzz ..channel one comein ..."
click "channel one here over "
Super cool ..hearing the squeltch working hah..
So we want someting that is dead when no one transmitting !!
It is a facility that mutes the reciever if there is no
valid transmission on the preset channel frequency Actual circuits may be messy but we have adoped easy opto Squeltch with LDR and BC 548
I tested with a china radio works very nicely
Keep the volume at zero the tuning led makes the LDR conduct and tiny transistor opens the volume ..crude but works nicely hot glue the pair inside the radio .
Step 3: The Antenna
Antenna , PTT switch wiring ,Battery
Antenna Making antenna that works very nicely is tricky but a aluminum rod hidden inside plastic works very well .
Need to remove that telecsopic antenna from the 2$ radio ..that looks crappy and not suitable for field use.
Trys combo of 4-6cm metals like copper and aluminum they will do the job .:)
Now we want the set to look cool like walkie talkie so
_black paint the radio ,except the display
--use a PEn yes PEN with black body to hide new Antenna metal ,use super glue
--you may like to keep a volume to limit max volume at too 10k pot should work with LDR in series
Step 4: Battery and PTT Switch
We want a rechargeable walkie , lets grab a 5000mAh power bank
use a resistor dropper for the reciever or diode dropper , the transmitter works at 5V
PTT switch (push to talk)
The walkies are one way talking devices normally
press to talk and release to recieve
As we are using cheap radio reciever we may lose the tuned freq. (cheap digital ones)
so instead of powering off the reciever we will just mute it while talking
See the PTT diagram .
Step 5: Final Thoughts
There are lot many possibilities like keeping a PIC micro to select channel , display battery levels
This is just an idea to get you a ready walkie with less hassle , yes it will be usable for sure .