Delay line? Are they still in use? - Page 1
Forum section: electronics / projects

author: romhunter
author_rank: Regular Contributor
timestamp: May 23, 2019, 07:09:10 pm
content: The title say it all. I happened to get ahold of a full tube (digital delay line) and wonder if they're still in use? Or widely use?

author: helius
author_rank: Super Contributor
timestamp: May 23, 2019, 07:44:55 pm
content: The salad days of delay line chips may be in the past, when they were used for applications as diverse as PAL television decoding and oscilloscope trigger circuits. The most common use these days may be in cheap effects pedals, where they can be used to build reverb and chorus circuits.

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 23, 2019, 08:12:46 pm
content: Got the datasheet? That should give ideas on what it can be used for.

author: Alex Eisenhut
author_rank: Super Contributor
timestamp: May 23, 2019, 11:35:08 pm
content: They still make em.https://www.digikey.ca/product-detail/en/texas-instruments/SN74LS31D/296-33992-5-ND/1590557But there's also the other style that is a hex inverter with a bunch of LC delays between the elements built into a capsule over the DIP14. They are usually tapped along the way.

author: wraper
author_rank: Unknown
timestamp: May 23, 2019, 11:43:24 pm
content: Quote from: Alex Eisenhut on May 23, 2019, 11:35:08 pmIt's not a delay line. Basically just a buffer offering a little bit more delay than most of this TTL series. Delay line is for example TDA4665.

author: romhunter
author_rank: Regular Contributor
timestamp: May 25, 2019, 05:45:38 pm
content: Here's something I found on a "parts board" few days ago, which give rise to this question:http://www.alldatasheet.com/datasheet-pdf/pdf/136508/DATADELAY/DLO32F-30MD1.htmlFull name is DDU66F, this is something similar.I got a very vague idea why they use them though. Can someone enlighten me on this matter?

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 25, 2019, 10:54:56 pm
content: They're for fine tuning clock phase back when discrete logic was in common use.

author: jmelson
author_rank: Super Contributor
timestamp: May 26, 2019, 12:01:09 am
content: Quote from: romhunter on May 23, 2019, 07:09:10 pmThe "digital" delay lines are used much less today as many ICs have various timing adjustment functions built in. They were often used in the past to align timing between various components so that data was clocked in at the best time. This is very rarely needed today, with FPGAs and such having far more sophisticated mechanisms. The digital delay lines have buffer-driver circuits after the passive delay line, integrated into the package.However, the passive delay lines can be used to delay analog signals in many signal processing systems.We use them in nuclear signal acquisition system to delay linear signals so that a "discriminator' has time to detect the arrival of the signal pulse and start/synchronize the acquisition.Jon

author: trevatxtal
author_rank: Contributor
timestamp: May 26, 2019, 04:55:45 am
content: So Modern!,The delay lines I worked on in the 70s consisted of a steel spring with a magnetic coupling at either end one could slide along the spring to get accurate delay.The capacity was 64 bits not bytes and most of the faults were with the driver and receiveramps.Banks of hundreds in large 19inch cabinets supporting memory cards of fer-rite beads woven with miles of fine wire.All for input to a IBM 360Bump a cabinet and 32 terminals would go down in the sales department.You can estimate my age.Trev

author: German_EE
author_rank: Super Contributor
timestamp: May 26, 2019, 07:48:09 am
content: Age? Somewhere between seventy and eighty. I started work in 1975 when they were still using punch cards and paper tape and I'm now 62.As for modern uses of delay lines, I used one about six months ago. I had a 45 MHz signal that I needed to delay by a quarter of a cycle (5.55nS) to generate a quadrature signal and a delay line did the job perfectly.