LVTTL to SPDIF - diyAudio
Go Back   Home > Forums > Source & Line > Digital Source

Digital Source Digital Players and Recorders: CD , SACD , Tape, Memory Card, etc.

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 25th August 2007, 09:48 AM   #1
Ardee is offline Ardee  England
diyAudio Member
 
Join Date: Nov 2005
Default LVTTL to SPDIF

Can anyone advise as to the best way to convert low voltage TTL to SPDIF, please? Quality is more important to me than cost/complexity.

Thanks.
  Reply With Quote
Old 25th August 2007, 10:50 AM   #2
bocka is offline bocka  Germany
diyAudio Member
 
Join Date: Jul 2003
Location: Hannover
Use a 74LV86 (or similar XOR-Gate) to obtain a SOUT and /SOUT signal. Use this differential signal to feed an AD8132 high-speed differential op-amp and use a balun SPDIF output transformer.
  Reply With Quote
Old 12th September 2007, 05:29 AM   #3
novec is offline novec  Norway
diyAudio Member
 
novec's Avatar
 
Join Date: Aug 2005
Send a message via MSN to novec
Does this compete with regular DITs like the Burr-Brown DIT4192 from TI? I do like the simplicity of it, and all I need is TTL-S/PDIF buffering, no sample rate conversion or anything.
  Reply With Quote
Old 12th September 2007, 07:45 AM   #4
Ardee is offline Ardee  England
diyAudio Member
 
Join Date: Nov 2005
I think the DIT4192 converts I2S plus user bits to SPDIF. My question was how to convert LVTTL SPDIF to something which will drive a 75ohm interface.

Thanks for the suggestion bocka , btw.
  Reply With Quote
Old 12th September 2007, 11:39 AM   #5
novec is offline novec  Norway
diyAudio Member
 
novec's Avatar
 
Join Date: Aug 2005
Send a message via MSN to novec
Of course, my bad.
  Reply With Quote
Old 12th September 2007, 12:37 PM   #6
diyAudio Member
 
Join Date: Oct 2001
Location: .
Quote:
Originally posted by Ardee
My question was how to convert LVTTL SPDIF to something which will drive a 75ohm interface.
CLC001
  Reply With Quote
Old 12th September 2007, 10:48 PM   #7
nonoise is offline nonoise  South Africa
diyAudio Member
 
Join Date: Jun 2006
Just keep in mind that the output level should be 500mv P-P into 75 Ohm +/- 20% This is if you prefer to keep to the standard (IEC60958-3)
  Reply With Quote
Old 13th September 2007, 01:44 PM   #8
gmarsh is offline gmarsh  Canada
diyAudio Member
 
gmarsh's Avatar
 
Join Date: Apr 2004
Location: Halifax, NS, Canada
Use a 5V powered HCT gate (74HCT04, Tinylogic chip, etc) to convert LVTTL to +5V CMOS. You can use a faster logic family (VHCT, ACT) but be careful with decoupling.

On the output of the gate, put a 0.1uF series ceramic capacitor for DC blocking, then a resistor divider of a 330 ohm series and 100 ohm shunt.

(Actually, re-arrange that - put the 330 ohm resistor directly at the output pin of the logic gate, followed by the series capacitor and 100 ohm shunt.)

This gives you a 1.5Vpp unloaded, 0.75Vpp loaded SPDIF output with a near-75-ohm source impedance.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
SPDIF on cdrom to SPDIF on Digi Crossover davidallancole Digital Source 0 11th January 2007 03:26 AM
cdrom spdif quality / sound card spdif metebalci Digital Source 0 2nd September 2006 07:16 PM
usb to spdif kit then_dude Digital Source 4 15th February 2006 02:32 AM
spdif out to double spdif in balthazard Digital Source 0 1st March 2005 06:52 AM
SPDIF: VCC / SPDIF which way round? rogercameron Digital Source 6 18th April 2004 10:29 AM


New To Site? Need Help?

All times are GMT. The time now is 02:24 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2