Author Topic: QSXM3 with LTC1050 servo?  (Read 2420 times)

0 Members and 1 Guest are viewing this topic.

Offline Brambus

  • New member
  • *
  • Posts: 3
  • Karma: +0/-0
  • Custom title, please change to something cool.
QSXM3 with LTC1050 servo?
« on: January 27, 2011, 08:35:12 PM »
Sorry for a stupid question, but i could not resist...  :?
 
I'm planning about building  QSXM3.
Before starting I was searching for a good substitute for MAX420 -
I know that it is possible to use OP07 etc. but having found the data sheet of LTC1050-CN8
i was thinking that maybe it would work.

Would it be enough to omit P7 P8 C79 C80 (i.e. the net around terminals 1-5-8) or am i totally out of way?
Thanks in advance.
Paolo

PS
I see now that 18 volts is the total  V+ to V-  power supply rating. Maybe this is the show stopper... :|
« Last Edit: January 27, 2011, 10:08:57 PM by Brambus »

Offline peranders

  • Administrator
  • Reached Nirvana
  • *****
  • Posts: 1227
  • Karma: +6/-0
  • Gender: Male
  • Forum owner
    • Sjöström Audio
Re: QSXM3 with LTC1050 servo?
« Reply #1 on: January 27, 2011, 10:19:12 PM »
LTC1050 could be used with some redesign but I'll recommend you a non-chopper type, like a medium speed, low noise type, capable of +- 15 volts. 5-15 V/us, 4 nV/Hz or less, 1 mV offset or less. Low input bias currents.
/Per-Anders Sjöström, owner of this forum

Homepage with my DIY hifi stuff

Offline Nugman

  • New member
  • *
  • Posts: 3
  • Karma: +0/-0
  • Gender: Male
  • Groupie - Just hanging around with the cool dudes
Re: QSXM3 with LTC1050 servo?
« Reply #2 on: January 20, 2018, 01:50:51 PM »
Hi Per-Anders,

I'm also looking for a substitute for the MAX420 in QSXM3. In another topic regarding the QSXM2 you were suggesting an OP07 instead. Would this work in the QSXM3 as a drop-in replacement with the same circuit around as with the MAX420? Could I use the OP07 just instead of the MAX420?

Many thanks in advance  for your advice.
Roland
« Last Edit: January 20, 2018, 02:04:26 PM by Nugman »

Offline peranders

  • Administrator
  • Reached Nirvana
  • *****
  • Posts: 1227
  • Karma: +6/-0
  • Gender: Male
  • Forum owner
    • Sjöström Audio
Re: QSXM3 with LTC1050 servo?
« Reply #3 on: January 20, 2018, 09:49:49 PM »
OP07 will work fine.
/Per-Anders Sjöström, owner of this forum

Homepage with my DIY hifi stuff

Offline Nugman

  • New member
  • *
  • Posts: 3
  • Karma: +0/-0
  • Gender: Male
  • Groupie - Just hanging around with the cool dudes
Re: QSXM3 with LTC1050 servo?
« Reply #4 on: January 20, 2018, 11:49:11 PM »
Hi Per-Anders,

thanks for the quick reply. I'm a little bit embarrased because I found that you already mentioned the OP07 in the original documentation. I was so focused on looking for a MAX420 and how to replace it, that I somehow missed that.  :oops:
You write that when using the OP07, P3/P7 should be used as well. How should the pot be adjusted then? Is there a measurement point that should have a certain voltage or current?
What value should the pot have? The datasheet of the OP07 recommends 20k, while the schematics show a 10k?

Thanks, Roland
« Last Edit: January 21, 2018, 12:00:46 AM by Nugman »

Offline peranders

  • Administrator
  • Reached Nirvana
  • *****
  • Posts: 1227
  • Karma: +6/-0
  • Gender: Male
  • Forum owner
    • Sjöström Audio
Re: QSXM3 with LTC1050 servo?
« Reply #5 on: January 21, 2018, 10:24:48 AM »
Start to use the OP07 without any trimming. I think it will work good. If you add a trim pot then the offset drift will be higher so it's good if you can avoid it. If you anyway want this pot use the recommended value in the datasheet.
« Last Edit: January 21, 2018, 10:30:46 AM by peranders »
/Per-Anders Sjöström, owner of this forum

Homepage with my DIY hifi stuff

Offline Nugman

  • New member
  • *
  • Posts: 3
  • Karma: +0/-0
  • Gender: Male
  • Groupie - Just hanging around with the cool dudes
Re: QSXM3 with LTC1050 servo?
« Reply #6 on: January 21, 2018, 12:03:46 PM »
Many thanks!