Build my own radio transmitter?

[badrisuper]

Hi all,
I like to build a small radio transmitter [Sending and Receiving]. I knew lot of people in this forum knows much about radio and transmitters. Guys please help me out or point a small tutorial and what are the components i need to do this. I am trying to do some radio related stuffs. I need to know about radio waves and how it is transmitted. I like to build a small radio transmitter and want to test how it is send and receive. I have been going through few sites. But help from people who knows about radio waves can give more understanding and speeden up my tries.

Thanks in advance
Badri M

 

[reubensm]

Do you intend to use your transmitter for amateur radio (HAM radio) or is it just for fun?

 

[Audiodoc]

A word of caution! Amateur radio is not allowed by Indian laws you need a license to run one that has a range over 200 meter. I have learnt it the hard way.

 

[badrisuper]

Do you intend to use your transmitter for amateur radio (HAM radio) or is it just for fun?

Its just for fun. What I am trying to do is - I want to build a device which has to send radio signals at the same time should receive signal from another same type of device. But the signal send by one device should not receive its own signal. Is it possible?

 

[reubensm]

A word of caution! Amateur radio is not allowed by Indian laws you need a license to run one that has a range over 200 meter. I have learnt it the hard way.

can you share with us, what happened, if its ok? just out of curiosity.

 

[reubensm]

Its just for fun. What I am trying to do is - I want to build a device which has to send radio signals at the same time should receive signal from another same type of device. But the signal send by one device should not receive its own signal. Is it possible?

all you need is 2 transmitters and 2 radio receivers. both transmitters need to be calibrated to different frequencies and the respective opposite radios need to be calibrated to corresponding frequencies...then you'll have a 2-way communication wireless system...there are loads of AM and FM transmitter schematics available online. even kits are available from vendors like kit n' spares.

i had done this for a school project many many years ago

 

[badrisuper]

all you need is 2 transmitters and 2 radio receivers. both transmitters need to be calibrated to different frequencies and the respective opposite radios need to be calibrated to corresponding frequencies...then you'll have a 2-way communication wireless system...there are loads of AM and FM transmitter schematics available online. even kits are available from vendors like kit n' spares.

i had done this for a school project many many years ago

It is ok for 2 devices i think. What if I have N number of devices. Can I make simultaneous communication? I have read one article about simultaneous communication through wireless signals. But it is not completed. Do you have solution for simultaneous communication using radio transmitter and receiver?

 

[reubensm]

It is ok for 2 devices i think. What if I have N number of devices. Can I make simultaneous communication? I have read one article about simultaneous communication through wireless signals. But it is not completed. Do you have solution for simultaneous communication using radio transmitter and receiver?

yes you can but all transmitters and radios must be tuned to the same frequency and while speaking, one speaker will have to say "over" at the end of the sentence, for the next speaker to speak up....guess you may have heard this in old hindi movies where there was 2-way communication.

 

[Audiodoc]

I had a commondo raid on my house in Srinagar fortunately I was studying in Army School and told them it was a school project.

I have many circuits of radiofrequency walkie talkies with a range of 15 km.

 

[anm]

badrisuper, I hope you are not setting up a comm channel for karachi

 

[reubensm]

yes, please be careful when using transmission equipment...keep the power as low as possible...transmitting without a broadcast or amateur radio licence is illegal.

 

[omishra]

yes, please be careful when using transmission equipment...keep the power as low as possible...transmitting without a broadcast or amateur radio licence is illegal.

Yes, As a student, once I was summoned to police station and warned. Someone hinted that my 20W transmitter was reason for malfunction of police wireless 20 KM away. In fact I built that one as a student project for removing VHF wirelink and used FM for (video+audio) and never used extensively. Somehow power transistor burnt and its dead.

For simplest, and for fun use FM kits, easy to to transmit and receive. Tuning is easy. Just decide you want from scratch DIY or use ready to assemble kits, another way of DIY.

 

[Rabepobemababe]

Infact, low-cost and good quality FM transmitter kits (a transmitter, coaxial cable, and a tunable ground-plane antenna) are at galore abroad. Companies are willing to ship these to India. But without an FM broadcast licence, you cannot legally import one into India. It is a criminal offence, and before you know, your nukkadwallah police station folks will arrest you and put behind bars. I was recently joking with my son, that he should start a pirate-radio for his school folks. However, knowing fully what may befall thereafter, I have not ventured beyond joking.

 

[reubensm]

FM transmitters can be used carefully though. Would kind of work if you live in a large housing complex spread over several acres or for school/college campuses.