These Delay Lines: what are they?

[Fred Abse]

Over time I've salvaged a number of delay lines from VCR's and other
equipment and would like to know what they are.

They are small, thin plastic boxes of various lengths and heights and
have 3 leads. Inside each is what looks like a piece of glass or ceramic
with wires from the 3 leads connected to gold pads on the edges of the
glass. Some are made by KSS and others by Asahi Glass Co. but I can't seem
to find descriptions of these on the web.

How do these work, and what would they be used for? Are they for the same
use as semicinductor delay lines?

No.

 

[Baphomet]

Over time I've salvaged a number of delay lines from VCR's and other
equipment and would like to know what they are.

They are small, thin plastic boxes of various lengths and heights and have
3 leads. Inside each is what looks like a piece of glass or ceramic with
wires from the 3 leads connected to gold pads on the edges of the glass.
Some are made by KSS and others by Asahi Glass Co. but I can't seem to find
descriptions of these on the web.

How do these work, and what would they be used for? Are they for the same
use as semicinductor delay lines?

Thanks
Jim
[email protected]

They are used to ensure that the video and chroma signals register (overlap,
coincide) by adding a predictable amount of time delay to the chroma signal
before recombining into a composite (I think).

http://www.toko.com.hk/Catalog/coil_filter/lc_filter/pdf/5vsw.pdf

 

[Baphomet]

a.. Component Video. There are two component-video formats; color difference
(Y, Pb, and Pr) found in broadcast and luma/chroma (Y-C), or S-VHS, found in
VCRs. Both have a luma (Y) bandwidth that's greater than the color (Pb/Pr or
C) bandwidth making it difficult to keep the signals time-coincident.
a..
a.. They are used to ensure that the video and chroma signals register
(overlap,
coincide) by adding a predictable amount of time delay to the luminance (Y)
signal
before recombining into a composite.

 

[Jim]

Over time I've salvaged a number of delay lines from VCR's and other
equipment and would like to know what they are.

They are small, thin plastic boxes of various lengths and heights and have
3 leads. Inside each is what looks like a piece of glass or ceramic with
wires from the 3 leads connected to gold pads on the edges of the glass.
Some are made by KSS and others by Asahi Glass Co. but I can't seem to find
descriptions of these on the web.

How do these work, and what would they be used for? Are they for the same
use as semicinductor delay lines?

Thanks
Jim
[email protected]

 

[Lord Garth]

Over time I've salvaged a number of delay lines from VCR's and other
equipment and would like to know what they are.

They are small, thin plastic boxes of various lengths and heights and
have 3 leads. Inside each is what looks like a piece of glass or
ceramic with wires from the 3 leads connected to gold pads on the edges
of the glass. Some are made by KSS and others by Asahi Glass Co. but I can't
seem to find descriptions of these on the web.

A Google search for <vcr delay line> yielded 43,300 hits.

How do these work, and what would they be used for? Are they for the
same use as semicinductor delay lines?

There is a possibility you could have a Surface Acoustic Wave device. A SAW
filter would appear to have interlaced 'fingers' on a substrate of glass.

 

[Fred Abse]

Tru words? Useless answers!!

The point I was making was that the OP stated that he could not find any
answers on the Web. This appears to contradict my experience. there is, in
fact, a large amount of information on the subject out there.

 

[ddwyer]

Over time I've salvaged a number of delay lines from VCR's and other
equipment and would like to know what they are.

They are small, thin plastic boxes of various lengths and heights and have
3 leads. Inside each is what looks like a piece of glass or ceramic with
wires from the 3 leads connected to gold pads on the edges of the glass.
Some are made by KSS and others by Asahi Glass Co. but I can't seem to find
descriptions of these on the web.

How do these work, and what would they be used for? Are they for the same
use as semicinductor delay lines?

Thanks
Jim
[email protected]

They are bulk acoustic delay lines
The bulk material is a special glass with zero temperature coefficient
of delay.
The path is folded so that the line is as small as possible.
Conversion from electrical to acoustic energy and the reverse is by
piezoceramic transducers generally the operating frequency is in the
range 1 to 10MHz.
In PAL TV s a delay line stores one picture line.

Digital processing now replaces these lines.
The first acoustic line I saw stored one picture frame for NSTC to PAL
conversion.
Over a period of 25 years the lines got cheaper and smaller, the one you
saw was probably a slice from a single block cut like bread into 100s of
slices.

 

[Jim]

Tru words? Useless answers!!

 

[Geir Klemetsen]

Over time I've salvaged a number of delay lines from VCR's and other
equipment and would like to know what they are.

They are small, thin plastic boxes of various lengths and heights and have
3 leads. Inside each is what looks like a piece of glass or ceramic with
wires from the 3 leads connected to gold pads on the edges of the glass.
Some are made by KSS and others by Asahi Glass Co. but I can't seem to find
descriptions of these on the web.

How do these work, and what would they be used for? Are they for the same
use as semicinductor delay lines?

Thanks
Jim
[email protected]

I wonder:
* Is it posible to make an oscillator where the frequens is depended of a
delay line? If so, is there a scheme on the net, or can some smart person
draw an example?
* Same question, but for an ceramic filter.?

And of course, The pin asignment. How to couple one if i want to delay a
signal?

 

[ddwyer]

I wonder:
* Is it posible to make an oscillator where the frequens is depended of a
delay line? If so, is there a scheme on the net, or can some smart person
draw an example?
* Same question, but for an ceramic filter.?

And of course, The pin asignment. How to couple one if i want to delay a
signal?

Yes an oscillator can be made employing glass bulk acoustic delay lines
the frequency of oscillation will be 1/delay time however the centre
frequency of the response will be 3MHz and the delay 1/64? vsec ie the
length of one TV line.
Hence or other wise the oscillator can be made to lock every 16kHz or so
The delay lines when matched will have a loss between 12 and 20db so the
amplifier must have a gain exceeding this.
The best way to make an oscillator that jumps every 16kHz centered on
3MHz will be to make it a tuned amplifier and tune across the band.

 

[Fred Abse]

the delay 1/64? vsec ie the
length of one TV line.

If it's PAL, it's 63.943 usec. (An integer number of periods at 4.43361875
MHz.)

God only knows how I dredged that up from memory, it's been hiding in
there a quarter century

 

[Michael A. Terrell]

If it's PAL, it's 63.943 usec. (An integer number of periods at 4.43361875
MHz.)

God only knows how I dredged that up from memory, it's been hiding in
there a quarter century

'bout time you let it out! ;-)

 

[Fred Abse]

(An integer number of periods at 4.43361875
MHz.)

Sorry, it's half-periods (just went and looked it up)

 

[Geir Klemetsen]

Yes an oscillator can be made employing glass bulk acoustic delay lines
the frequency of oscillation will be 1/delay time however the centre
frequency of the response will be 3MHz and the delay 1/64? vsec ie the
length of one TV line.
Hence or other wise the oscillator can be made to lock every 16kHz or so
The delay lines when matched will have a loss between 12 and 20db so the
amplifier must have a gain exceeding this.
The best way to make an oscillator that jumps every 16kHz centered on
3MHz will be to make it a tuned amplifier and tune across the band.

Then i guess I can do it this way (Make sense if seen in fixed font):



+-----------------------------------------------------------------+
| |
| +------------+ +-----------+ +-----------------+ |
+--| Delay line |--------| Amplifier |------| Schmitt trigger |---+
+------------+ +-----------+ +-----------------+

Where either the amplifier or the schmittrigger (but not both) invert the
signal

 

[ddwyer]

Then i guess I can do it this way (Make sense if seen in fixed font):



+-----------------------------------------------------------------+
| |
| +------------+ +-----------+ +-----------------+ |
+--| Delay line |--------| Amplifier |------| Schmitt trigger |---+
+------------+ +-----------+ +-----------------+

Where either the amplifier or the schmittrigger (but not both) invert the
signal

If its a pal line tune the input and output transducers with inductors
to give overall loss of 12 to 20db.
AC amplifier gain greater than 20db centered on 4ish MHz without
schmitt to set in oscillation try to keep the transfer function linear
ie no schmitt in the loop.