I found a few circuits for TV transmitters, but no receivers.

I've looked at other simpler RF transmitters and receiver, but it's not obvious to me how to reverse the circuit that I have.

I want to send an expendable RC car into a collapsed tunnel, cable wouldn't work it's a labyrinth.

Can you give me an example of a vhf receiver and help me understand how it works?


closed as too broad by brhans, Transistor, Sparky256, Chris Stratton, Leon Heller Oct 14 '18 at 8:20

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ Welcome to EE.SE. These questions require a broad scope of answers, many of which will be opinions. Pardon me saying so, but I think you are in a bit over your head. Prove you understand the details of what is required and we will help. \$\endgroup\$ – Sparky256 Oct 13 '18 at 23:05
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    \$\begingroup\$ "Expandable" or do you mean expendable? \$\endgroup\$ – Transistor Oct 13 '18 at 23:09
  • \$\begingroup\$ Expendable don't shoot me, please? Yes I'm a beginner and don't have the necessary knowledge. For a long time I wanted to use a pic32,wifi and a digital camera for this project, that's how lost I am. \$\endgroup\$ – Wtom193 Oct 14 '18 at 0:00
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    \$\begingroup\$ @Wtom193 Don't stress. We are just giving the best advice we are able. We want to be sure of what you're asking before we put a lot of effort into a really good answer and we want the questions to be helpful for everyone who comes searching for them. Also, the better your question is, the better the chance someone will really put their heart into an answer. \$\endgroup\$ – K H Oct 14 '18 at 0:18
  • \$\begingroup\$ You wouldn't do this (at least not legally) with a broadcast TV transmitter. There are video links commonly used for RC hobby applications (WiFi is also used but laggy) however your description of the environment sounds like one which wants a wire/fiber tether \$\endgroup\$ – Chris Stratton Oct 14 '18 at 1:55

Your linked transmitter is very elementary. But if there's an analog composite video signal feeded to connector "Video input" with right amplitude and the potentiometer is well adjusted, a normal analog TV-receiver can really catch and show the video.

The reverse circuit - a receiver which outputs analog video can in theory be a simple superregenerative AM receiver, because your transmitter makes AM, not vestigial sideband modulation signal like proper norm respecting TV transmitters. Unfortunately video display equipment need strictly controlled video signal voltage for acceptable image and no simple receiver will provide it. That's why you actually need a proper analog TV receiver.

ADD: I just realized that you want to send signals through soil and rock. It is probably impossible except by using very low frequency which would need huge antennas. The water in the soil will attenuate VHF and UHF range signals to non-detectable very soon. You should do some tests before continuing the project.

  • \$\begingroup\$ I see thanks! Do you think sg like RTL2832U usb dongle would work? I want the receiver to be portable maybe a laptop or tablet with otg or raspberry pi. \$\endgroup\$ – Wtom193 Oct 14 '18 at 0:04
  • \$\begingroup\$ @Wtom193 RTL2832U is a receiver for modern digitally coded TV signals, you need a NTSC or PAL receiver. Your transmitter is for NTSC and PAL analog video signals. If you do not know those legacy analog TV systems, you need some local help. \$\endgroup\$ – user287001 Oct 14 '18 at 1:13
  • \$\begingroup\$ rtl-sdr.com/analogue-tv-with-rtl-sdr I found this so I guess it would be a start. I think the signal would bounce in the tunnel. \$\endgroup\$ – Wtom193 Oct 14 '18 at 11:07
  • \$\begingroup\$ @Wtom193 Your software radio link presents a complex project itself. Get an old TV receiver from analog television broadcast era. Start by testing that bouncing. It is theoretically possible if the wavelength is shorter than double diameter of the tunnel. Due the irregular bouncing route and unpredictable position of the transmitting antenna prepare to use circular polarization and diversity receiver. I bet digital signals would be more flexible because you can reduce data rate in case of weak signal and get sharp images. Analog TV needs much more powerful signal. \$\endgroup\$ – user287001 Oct 15 '18 at 2:33
  • \$\begingroup\$ It's only need tvsharp or am I missing something? I can't find any analog tv receiver on a reasonable price. Yes but digitalizing the camera output would not be that easy, I know use a digital camera but it needs synchronization that is where I was stuck and give up. \$\endgroup\$ – Wtom193 Oct 15 '18 at 10:22

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