Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Building a TV transmitter (transmitting only video)

Status
Not open for further replies.

vishnupg

Member level 3
Joined
Dec 24, 2009
Messages
67
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,288
Location
india
Activity points
1,731
can any one help me build a tv transmitter for my final year project.i wnt to transmit video from a camera.i need it to be transmitted within a large auditorium

Added after 1 minutes:

i neeed to transmt only video
 

davenn

Advanced Member level 3
Joined
Jul 1, 2009
Messages
844
Helped
192
Reputation
384
Reaction score
163
Trophy points
1,323
Location
Sydney, Australia
Activity points
6,381
Re: tv transmitter

what freq do you want ?
is it to be received on a normal TV ?
more than 1 TV or only 1 receiver needed ??


cheers
Dave
 

BigBoss

Advanced Member level 5
Joined
Nov 17, 2001
Messages
5,116
Helped
1,529
Reputation
3,056
Reaction score
1,376
Trophy points
1,393
Location
Turkey
Activity points
30,765
tv transmitter

Use a TV modulator and then amplify the output signal with an power amplifier ( you'll need apparently 1-2W output power) the connect a folded dipol antenna thru a balun circuit 300Ohm-75Ohm..
 

vishnupg

Member level 3
Joined
Dec 24, 2009
Messages
67
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,288
Location
india
Activity points
1,731
Re: tv transmitter

i want to transmit around 200mhz.i want it to be received on a normal tv.
i am planing to make video out by detecting video from if of the tv tuner
 

davenn

Advanced Member level 3
Joined
Jul 1, 2009
Messages
844
Helped
192
Reputation
384
Reaction score
163
Trophy points
1,323
Location
Sydney, Australia
Activity points
6,381
Re: tv transmitter

ok its time for you to use google

remember google is your friend :)

here's one for a start https://www.zimbio.com/Transmitter+Circuit/articles/irvt901eofS/VHF+Video+Transmitter+60+200+MHz

there are many other listings

stick another amplifier stage on the output to get up to 0.5 to 1W and you will be in business :)

cheers
Dave
VK2TDN

Added after 2 minutes:

fuuton said:
www.batc.org.uk, take a look at this

you need to remove the comma from the end of fuuton's listing else you wont get to the site

try .... www.batc.org.uk

when posting links be careful of any added text it will stop the link from working

cheers
Dave
VK2TDN
 

zlatkoMM

Full Member level 5
Joined
Apr 4, 2008
Messages
296
Helped
13
Reputation
26
Reaction score
7
Trophy points
1,298
Location
Croatia
Activity points
2,884
Re: tv transmitter

Hallo any comments ?????????????
 

betwixt

Super Moderator
Staff member
Joined
Jul 4, 2009
Messages
15,161
Helped
4,946
Reputation
9,913
Reaction score
4,758
Trophy points
1,393
Location
Aberdyfi, West Wales, UK
Activity points
128,782
Re: tv transmitter

The schematic will work - but - any design that does not have a buffered output such as that one will be very prone to frequency shift if anything moves in the vicinity of the antenna. You might find the frequency shifts several MHz if someone walks past it or something is moved nearby. It is far better to use an extra stage to isolate the effects of the antenna from the tuned circuit to prevent the drift occurring. Even better is to stabilize the frequency with a PLL but that involves quite a lot of extra circuitry.

Brian.
 

davenn

Advanced Member level 3
Joined
Jul 1, 2009
Messages
844
Helped
192
Reputation
384
Reaction score
163
Trophy points
1,323
Location
Sydney, Australia
Activity points
6,381
Re: tv transmitter

betwixt said:
It is far better to use an extra stage to isolate the effects of the antenna from the tuned circuit to prevent the drift occurring.
Brian.

Agreed, would help keeping the system stable :)

betwixt said:
Even better is to stabilize the frequency with a PLL but that involves quite a lot of extra circuitry..

true but a total wast of time. With the wide bandwidth of the TV signal and added to that the AFC of the receiver 10's or even several 100kc of freq drift is nothing compared to the overall bandwidth of the signal and it will never be noticed.

Dave
VK2TDN
 

betwixt

Super Moderator
Staff member
Joined
Jul 4, 2009
Messages
15,161
Helped
4,946
Reputation
9,913
Reaction score
4,758
Trophy points
1,393
Location
Aberdyfi, West Wales, UK
Activity points
128,782
Re: tv transmitter

I would agree with the drift scenario to a point but you are assuming a good layout and selected components. Even a few pF change in capacitor values from temperature change or variation in supply voltage could make it drift beyond the limits of TV AFC. It also depends on whether the TV is AM or FM as the circuit produces a mix of the two. AM tends to be less tolerant of drift.

It wouldn't be too difficult to add something like an SP5050/5060/5070 PLL and a quartz crystal to keep it on frequency.

Brian.
GW6BWX
 

davenn

Advanced Member level 3
Joined
Jul 1, 2009
Messages
844
Helped
192
Reputation
384
Reaction score
163
Trophy points
1,323
Location
Sydney, Australia
Activity points
6,381
Re: tv transmitter

Hey Brian,

thanks for signing with a callsign :) tis good to see another amateur operator
on here

seriously tho its not really a problem I have built and regularly use ATV transmitters from 440MHz to 24GHz and even drifts up to 500kHz are not really a problem. The worse units are the 10gig and 24gig Gunn Osc based units where
temperature drift can be substantial.
the only phase locked ATV TX I have is the 5.7GHz one and thats only cuz its based on one of those A/V senders
see https://www.sydneystormcity.com/atv.htm for some of my activities
also playing up to 24GHz on voice as well.

cheers
Dave
VK2TDN
 

123jack

Advanced Member level 2
Joined
Apr 21, 2010
Messages
547
Helped
91
Reputation
182
Reaction score
77
Trophy points
1,308
Location
UK
Activity points
5,357
tv transmitter

I've tried 7 different models of those AV senders (yes 7 different) and every single one of them were appaling. I tried all the 2.4's and the 5.1 I could get

Someone walks past - no signal.
Weather changes - no signal
It's thursday - no signal
Someone in the next room - no signal
Need to move it 3 feet over every 2 hours or - no signal

The comments here suggest maybe why?
Does anyone make a reliable AV sender anywhere?
(question rhetorical - I've given up!) ;-(

jack
 

davenn

Advanced Member level 3
Joined
Jul 1, 2009
Messages
844
Helped
192
Reputation
384
Reaction score
163
Trophy points
1,323
Location
Sydney, Australia
Activity points
6,381
Re: tv transmitter

wow bad luck Jack

a number of us down here in Australia have had awesome success with the 2.4 and the 5.8 GHz units.
If you are going to use them for anything serious like us guys locally have been doing .... firstly get rid of the useless patch antenna and the very lossy length of teflon coax connecting the antenna to the module.
We used (as can be seen in my www page pix) UT141 coax to SMA or N type connectors and from there short lengths (1metre or less) of low loss coax to hi gain gridpac antennae 22dBi or greater gain.

on my 5.8GHz unit which was putting out ~ 25mW I got a slightly snowy pic received at 76km !!!
power levels out of the units we were playing with varied from ~ 10mW to as much as 35mW, as read off the trusty ol' HP432A power meter

to be honest havent used them around home hahaha its been all long distance ATV (Amateur TV) work... hilltop to hilltop.
but even if I was to, I would use much better coax and antennae

cheers
Dave
VK2TDN
 

123jack

Advanced Member level 2
Joined
Apr 21, 2010
Messages
547
Helped
91
Reputation
182
Reaction score
77
Trophy points
1,308
Location
UK
Activity points
5,357
Re: tv transmitter

Hi dave

I guess when I have time I may look into it as a hobby thing.
I don't know what the power levels are or the local regulations for that - maybe
thats an issue too.

I just got tired of wasting petrol driving back and forth to various shops to get
replacements. Perhaps I should just hardwire it :|

jack
 

zlatkoMM

Full Member level 5
Joined
Apr 4, 2008
Messages
296
Helped
13
Reputation
26
Reaction score
7
Trophy points
1,298
Location
Croatia
Activity points
2,884
Re: tv transmitter

Hi again ...
Ive build this one with 2SC1815 transistor and works but i dont have problem with
frequency drift.Im in eorupe and i use 4 chanel PAL B TV to revcive signal.
somwhere about 62 MHz and works prety stable but i have problem with level
of video signal from scart of my digital reciver , i think that is signal to strong
and couse to much AM modulation .
Maby is problem becose i dont put 75 ohm resistor into video input stage?
what you mean about that problem...
 

vishnupg

Member level 3
Joined
Dec 24, 2009
Messages
67
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,288
Location
india
Activity points
1,731
Re: tv transmitter

so the circuit works right.so let me try it buddy.i have tried many but only succeds in getting a black screen on tv.cant get the picture.i am giving the video fron a camera.if u have any good working circuits pls post them for me
 

Status
Not open for further replies.

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top