I find your project very exciting. Do you think it would be possible to convert a tv to radar PPI display?

 

I find your project very exciting. Do you think it would be possible to convert a tv to radar PPI display?

An interesting idea! PPI's generally use phosphors that don't fade as fast as in TV's so that the image on the screen remains persistent throughout the sweep.

Most PPI displays these days, however, use raster displays, so it is plausible that this could be achieved through software.

The arduino, however, isn't quite the right platform for this. Maybe using an ARM powered device or FPGA would be more suitable.

Is this something you're planning on doing? The program above just uses a circular buffer to obtain information and dump it to the display, something that could easily be done with the radar setup.

Are you planning to hook this up to an actual radar or just use it as a show-piece? If it's the latter, I could help you out a bit.

 

Wow check this out, I was ripping it apart and found a component I hadn't noticed, a teeny tiny galvanometer! I wonder what mischief I could do with this...

 

I think you'll find it's actually a moving coil milliamp-meter (or possibly microamp meter).

A few people have done this kind of conversion before you - some links here for inspiration - I'm sure you can find more:
http://www.instructables.com/id/How-To-Make-A-CRT-TV-Into-an-Oscilloscope/?ALLSTEPS
http://www.instructables.com/id/Fully-Functional-Television-Oscilloscope/?ALLSTEPS
http://www.instructables.com/id/Make-an-oscilloscope-out-of-an-old-Crt-computer-mo/?ALLSTEPS
http://www.instructables.com/id/Mini-TV-Oscilloscope/?ALLSTEPS

Be careful - inside of TV's BITE!

HTH

 

I think you'll find it's actually a moving coil milliamp-meter (or possibly microamp meter).

Galvanometer is the mechanism, ammeter the function, no?

That last link is cool. I've ripped most of the circuitry apart now unfortunately

 

Hello,

Read the following pages from the eBook:
Voltmeter design
Ammeter design

Bertus

 

Haha yes I understand that, but the actual device has no series or parallel resistance, it's just a galvanometer. I believe there were internal switches that changed it's function depending on whether the charging switch was on - it would either indicate the charge state of the battery (low current meant fully charged batteries) or the if the set was tuned in properly (high current meant it was tuned correctly).

 

Thanks. I am honoured. As a matter of fact, I just want it for display. No radar...yet. Well, I am trying to build an antenna and display its rotational direction on the scope or if possible a computer display, whichever is faster and easier for a rather novice like me and of course cheaper. Some form of servomech and required waveforms to get the trace and rotate with the antenna. Your help would be appreciated.

 

Yes indeed, using the TVout library, which can be found here. It says it works with RCA plugs, but it also works with standard aerials.

But what is the hardware you are using for the signal?

 

I have a choice: an old tv set and a computer screen. I have both.

 

But what is the hardware you are using for the signal?

Literally, two normal wires connected to the arduino as per the library instructions, with the signal wire connected to the central pin of the antenna receiver and the ground wire to the outer sheath. Apart from the 2 resistors mentioned in the library, no other hardware.

 

Literally, two normal wires connected to the arduino as per the library instructions, with the signal wire connected to the central pin of the antenna receiver and the ground wire to the outer sheath. Apart from the 2 resistors mentioned in the library, no other hardware.

Is the the VHF input of the TV or the composite video?

 

To the VHF aerial input yes I found even when he arduino wasn't physically connected te set wa able to pick up the signal, probably due to the analog switch off here

 

It must have a rf modulator then???

I assume you have to put your tv on channel 2 or 3? Is there a switch on the audrino for that?

 

No i don't believe so, but the way the signal is encoded is the important bit which is what the TVOut library of the arduino takes care of. It can output in either PAL or NTSC (I'm in France so actually the TV was SECAM but it's pretty much the same as PAL) so when connected directly to the VHF aerial input of the television, when tuned right, the picture comes up.

I'm not sure what channel it was because the device had manual tuners, but it was high in the VHF band.

I think when the arduino wasn't connected, the wires I had hooked up to it must've acted as a sort of transmitter aerial. Without the wires in, nothing would have been picked up (I assume, untested).

It's worth having a look at the TVOut library here:

http://code.google.com/p/arduino-tvout/

Basically, the library just outputs a signal according to each set standard (PAL, NTSC) with some nice functions for drawing lines and circles and stuff.