Radio delay to sync with TV video

Perhaps Don gets very special cable.

Just use a long piece of coaxial cable.

One over ??

...Jim Thompson

Making an analog audio delay line with a bunch of caps and coils might be fun, though.

The only MIT grad that I knew told me they always looked forward to playing against WPI, because then they could get there scoring equipment fixed by people who could actually recognize a soldering iron.

Was that the case when you were there?

Faster than a speeding bullet ;-)

...Jim Thompson

When I was a student at MIT we had some special coax in the Transmission Lines Lab. Its center conductor was a coil so that the effective inductance per foot was quite large. I can't quite recall now, but I believe it may have had a delay of about 100uS per foot, making delay experiments into non-matched loads a piece-a-cake.

...Jim Thompson

I had a full scholarship covering tuition and books. But I had to cover room and board. So I worked as a technician in Building 20 (but I already had some experience... my dad had a radio/TV repair shop and a hardware store.

But most everyone I hung out with at the very least built their own kits. (Except for the PhD's who needed help wiping ;-)

...Jim Thompson

Tape loop should work, but you adjust the delay by changing the spacing between the heads. I don't remember what the cassette tape speed is, but around 1 ips. So, the spacing would have to be around 4 - 5 inches.

You could do it electronically with an A/D, D/A converters and some storage. For 20 KHz sampling rate you would need 80 - 100 Kwords of storage. Probably easier to do it in hardware than sticking a micro in it. Essentially a FIFO, where you write in and read out with the same clock, but you don't start reading out until the desired number of samples have been stored.

Tam

Its expensive

but you could diy with a audio ADC, big chunk of 16bit memory, a few counters and audio DAC. Not a beginners project

martin

Serious error. All shortcuts have disappeared. Screen. Mind. Both are blank.

DOH, why didnt I think of that!

martin

Serious error. All shortcuts have disappeared. Screen. Mind. Both are blank.

following Allans post

martin

Serious error. All shortcuts have disappeared. Screen. Mind. Both are blank.

storing the 1,227,600 miles of cable might be a problem though!

Unfortunately I don't have a PC in the area of the audio equipment.

seconds

imagine I

and

dlay

spacing

but

storage.

Probably

a FIFO,

start

Tape? What's that? ;-)

I found the following IC

Allows for 2 seconds of delay, so I'm sure I could hook up 3 in series to accomplish this task... Maybe I'll get it done for next football season!

= PC + soundcard + software

The hardware is trivial, but the software is not a beginners project.

Regards, Allan

This is not very practical.

Instead, modulate a laser diode and run the laser light through fiber optic cable. The resulting 5 billion or so feet of fiber will be much more manageable than the corresponding coax delay line.

You might still need a couple of repeaters.

--Mac

Back in the good old days when the BBC started up Radio1, the "pop" channel the designs dept came up with an audio compressor that had a

martin

Serious error. All shortcuts have disappeared. Screen. Mind. Both are blank.

Bounce the HDTV signal off the moon. Move moon for best sound.