VHF Audio/Video Camera

[transistor495]

Hi,
For a long time I have this VHF TV Transmitter circuit, but now I found it useful for transmitting an IR Night-Vision camera output to the television receiver in my home.

The Infrared Camera/mic unit will be located on the gate of my home.
I want you people to closely look into the circuit and tell me if there is any chance of faults/wrong-connection anything. Also I don't get that T1. Where is the internal capacitor of T1 mentioned on the circuit? Will it have normal range as like fm's of few hundred meters? I want 100 meters.
My home is in an independent area so I need it and no chance of hacking of the transmitted signal especially on the night time!
**broken link removed**

 

[HarveyH42]

Looks like a circuit from a kit I built about 10 years ago, which didn't work very well (maybe 30 feet, poor image, unstable...). Secure? Anybody with a portable TV can receive. Fortunately for you, broadcast TV isn't so popular anymore, and on Feb. 17, 2009, should be pretty much phased out...

 

[JimB]

The circuit is a piece of junk.

The VHF oscillator is just a free running oscillator with the antenna connected to the tuned circuit. It will drift and be unstable.

I think T1 in conjunction with Q1 is intended to provide the sound carrier, at 5/5.5/6 Mhz (or what ever the Indian tv system uses) from the vision carrier, where is the capacitor? In the can with T1, whatever that is supposed to be.

All in all a piece of junk guaranteed to crap all over the other users of the RF spectrum.

Fortunately for you, broadcast TV isn't so popular anymore, and on Feb. 17, 2009, should be pretty much phased out...[\quote]
In the USA maybe, but not necessarily in India.

JimB

 

[transistor495]

The circuit is a piece of junk.

The VHF oscillator is just a free running oscillator with the antenna connected to the tuned circuit. It will drift and be unstable.

All in all a piece of junk guaranteed to crap all over the other users of the RF spectrum.

JimB

I think I can make the Oscillator section separate from the Antenna. For frequency drifts shall I put a crystal controlled oscillator?

It will be operated on an independent area. So no issue of interference for other users. I think the audio will be transmitted clearly and not much sure about the video part. Need to experiment and is that a proper way of video modulation?