New DIY Project for measuring noise : 10Hz..100kHz LNA // 1MHz RMS-DC converter - Page 7 - diyAudio
Go Back   Home > Forums > Design & Build > Equipment & Tools

Equipment & Tools From test equipment to hand tools

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 11th April 2013, 06:25 AM   #61
diyAudio Member
 
Join Date: Apr 2013
Location: Rotenburg/Wmme - Germany
Hello Frex,

thanks for your fast response, and yes I know about the LT1088, it's obsolete for a long time, although an FAE has tried to tell me, that Linear Technology never did quit production of chips. :-)
However, at the moment I have to handle some other urgent problems, but when everything is
silent again I would like to contact you again for sending over a PCB. By the way, I have got an old HP3400A TRMS-Multimeter for a reasonable price, that works pretty fine. "The holy gral" of TRMS-measurerment. ;-)

Kind regards,
Michael
  Reply With Quote
Old 11th April 2013, 06:27 PM   #62
Frex is offline Frex  France
diyAudio Member
 
Join Date: Nov 2009
Hello,

The ERMSDCv1 is greatly inspired from LT's applications notes about LT1088.
I had also bought some time ago a thermal RMS voltmeter ( the HP3403A,
same as 3400A with digital readout) and i was very dissapointed by both..
The measurement dynamic of thermal voltmeters is very low and you need to play often with ranges (non-linearity at low-level).
It's because of this that i have build another design (ERMSDCV2) using the newer LTC1968 IC that work much better than LT1088 in it's bandwidth.
Today, LT1088 can only be a good choice if you need measurement bandwidth beyond 1MHz.
Regards.

Frex
  Reply With Quote
Old 20th October 2013, 10:01 AM   #63
gnomcat is offline gnomcat  Bulgaria
diyAudio Member
 
Join Date: Jun 2006
Location: Sofia
Hi, Frex.
First excuse me for my bad english. Congratulations for your wonderful device.
I have a question. In ERMSDCV2.3 the levels a clip indicator are +2V / -2V. This corresponds to 2Vpk (4Vpp, 1.41Vrms - AC sinusoidal). At this level after attenuator (R68-1K / R75-549R) on an input LTC1968 enter signal 0.705Vpk (1.41Vpp, 501mVrms). On the schematic it's labeled: max 1Vpp (353mVrms). What do you mean?. In ERMSDCV2 design clip levels are +0.5V / -0.5V (on input LTC1968: 0.5Vpk or 1Vpp).
I want to ask you about something else. The datasheet (LTC1968) says: "Differential input range is 1VPEAK". In AC 1Vpeak(Vpk) = 2Vpp. Does this mean that the input IN1 (LTC1968) I can apply a 1Vpk(2Vpp) if IN2 is GND? Or in this case the error is increased? Thank you in advance !

Best regards
Ivan
  Reply With Quote
Old 7th November 2013, 12:13 AM   #64
diyAudio Member
 
Join Date: Oct 2013
Greetings Frex !

Thanks again for replying to a post of mine, considering a cheap way to use a voltmeter to read millivolts. That is what led me to this post. I have to say that I'm only JUST savvy enough concerning electronics, to be able to appreciate your knowledge and talent. You have a great talent for presenting your projects on this forum as well. When you get everything together on the project presented, I would be very interested in getting in on any PCB deal you come up with. I'll try to keep up with this post for that reason, and for the opportunity to learn more. I wish you, and all posting here, the utmost in success with ALL of your projects. Hopefully, some will "rub off" on me as well.

Sincerely, tonequester.
  Reply With Quote
Old 8th November 2013, 04:23 AM   #65
Frex is offline Frex  France
diyAudio Member
 
Join Date: Nov 2009
Hello,

Ivan,
For the overload detecting level of +/-2V, you have +/- 708mV at the LTC1968 inputs.
No matter if it is AC or DC level, both can overload the IC.
The IC is given to +/-1Vpeak max for a 1% accuracy.
But if you want maintain better accuracy, you need to slightly below this level in any conditions.
So, if the overload level indicator start to blink, you must be careful about precision. Despite that, in some case (sine wave: low CF signal) you can apply higher level signal without concern.

Tonequester,
Thank you very much, and welcome to DIY electronic world.


Frex
  Reply With Quote
Old 8th November 2013, 09:25 AM   #66
gnomcat is offline gnomcat  Bulgaria
diyAudio Member
 
Join Date: Jun 2006
Location: Sofia
Frex, thank you very much for the comprehensive reply !
  Reply With Quote
Old 9th November 2013, 12:36 AM   #67
diyAudio Member
 
Join Date: Oct 2013
Question Group pcb buy

Greetings Frex, tonequester here.

I hate to be a bother, but I have never dealt with Euros before. I had to look up the symbol to make sure, that was what you were asking 30 of, for the group pcb buy. can you tell me if currency is exchanged automatically when using pay pal(I've never used it before), or if I need to get a current quote on how many dollars, 30 Euros are worth. Again, I'm sorry to bother, but I'm new to Internet purchasing, as well as forums. Thanks in advance, if you or anybody else can help me out here. tonequester out.
  Reply With Quote
Old 9th November 2013, 01:26 AM   #68
AR2 is offline AR2  United States
Master Burner
 
AR2's Avatar
 
Join Date: Dec 2002
Location: San Francisco, California
Quote:
Originally Posted by tonequester View Post
Greetings Frex, tonequester here.

I hate to be a bother, but I have never dealt with Euros before. I had to look up the symbol to make sure, that was what you were asking 30 of, for the group pcb buy. can you tell me if currency is exchanged automatically when using pay pal(I've never used it before), or if I need to get a current quote on how many dollars, 30 Euros are worth. Again, I'm sorry to bother, but I'm new to Internet purchasing, as well as forums. Thanks in advance, if you or anybody else can help me out here. tonequester out.


30 Euros = $ 40.06

When you pay over paypal, you will specify currency, in this case Euro, € here is the symbol, and the amount 30. Paypal gives you an option to use their conversion or to use currency conversion from your bank. My advice would be to use currency conversion from your bank, since you will always get better rate. Regardless of which one you choose there will be a minimal difference with such a small amount. Type email address for Frex and send. It cannot be simpler.
You will be charged in US $ and Frex will receive payment in €.
__________________
www.burningamp.com

Last edited by AR2; 9th November 2013 at 01:28 AM.
  Reply With Quote
Old 9th November 2013, 02:20 AM   #69
diyAudio Member
 
Join Date: Oct 2013
Greetings AR2 and thanks. OL' tonequester really appreciates your giving me the "low down" on this matter. I"m pretty far behind the times, but trying hard to catch up. I just don't have any friends or relatives who I can go to for such information. It may be hard to believe but some of my bunch rely on ME, to help them with computers and such ! Often they are sh__ out of luck. I just joined PC Help forum tonight. I'm hoping that I can bother those guys on some of these matters that don't really pertain to electronics/audio/music. One things for sure. I can't get any WORSE OFF, than I am right now ! Actually, I'm better off for joining this forum, and meeting guys like you.

Thanks again, and glad to "meet" you here. tonequester out.
  Reply With Quote
Old 9th November 2013, 02:29 AM   #70
AR2 is offline AR2  United States
Master Burner
 
AR2's Avatar
 
Join Date: Dec 2002
Location: San Francisco, California
Quote:
Originally Posted by tonequester View Post
Greetings AR2 and thanks. OL' tonequester really appreciates your giving me the "low down" on this matter. I"m pretty far behind the times, but trying hard to catch up. I just don't have any friends or relatives who I can go to for such information. It may be hard to believe but some of my bunch rely on ME, to help them with computers and such ! Often they are sh__ out of luck. I just joined PC Help forum tonight. I'm hoping that I can bother those guys on some of these matters that don't really pertain to electronics/audio/music. One things for sure. I can't get any WORSE OFF, than I am right now ! Actually, I'm better off for joining this forum, and meeting guys like you.

Thanks again, and glad to "meet" you here. tonequester out.
I am glad to help. This is certainly an outstanding forum. You will like it here.
Best
__________________
www.burningamp.com
  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
Simple 60dB discrete low noise amplifier (lna) iko Solid State 465 19th June 2014 06:04 AM


New To Site? Need Help?

All times are GMT. The time now is 12:40 PM.


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