UK Vintage Radio Repair and Restoration Powered By Google Custom Search Vintage Radio and TV Service Data

Go Back   UK Vintage Radio Repair and Restoration Discussion Forum > Other Discussions > Homebrew Equipment

Notices

Homebrew Equipment A place to show, design and discuss the weird and wonderful electronic creations from the hands of individual members.

Reply
 
Thread Tools
Old 21st Aug 2022, 7:58 pm   #21
megasounds
Diode
 
Join Date: Aug 2022
Location: Nieuw-Vennep, Netherlands.
Posts: 3
Default Re: SINAD Meter - Home Made for 15.

Hi knoxieman

just a question
in your zip file there is a VER 3 sch.jpg file
Since i want to build one can you send me a proper and clear VER 3 sch.jpg ?

This one is very hard to read and some components are unclear.

many thanks in advance
PD9MWO
megasounds is offline   Reply With Quote
Old 15th Sep 2022, 5:15 pm   #22
megasounds
Diode
 
Join Date: Aug 2022
Location: Nieuw-Vennep, Netherlands.
Posts: 3
Default Re: SINAD Meter - Home Made for 15.

Click image for larger version

Name:	WhatsApp Image 2022-09-15 at 19.07.47.jpeg
Views:	104
Size:	27.2 KB
ID:	264773
Finally built the Ramsey Electronics version. Works great!

PD9MWO
megasounds is offline   Reply With Quote
Old 16th Sep 2022, 7:36 pm   #23
Cruisin Marine
Hexode
 
Join Date: Jul 2018
Location: London, UK
Posts: 446
Default Re: SINAD Meter - Home Made for 15.

Nice one!
__________________
"Behind every crowd, there's a silver Moonshine"
Cruisin Marine is offline   Reply With Quote
Old 21st Sep 2022, 5:08 pm   #24
sentinel040
Hexode
 
Join Date: Feb 2007
Location: Near Lichfield, Staffordshire, UK, most of the time and Crystal Palace, S London, some of the time..
Posts: 296
Default Re: SINAD Meter - Home Made for 15.

If I may, I would like to ask a question about this.

Having tried to get my paws on an original one, I started to build one of these a bit back when I first saw the post. I purchased the meter from the link provided and removed the internal series resistor (it helps). I used the 8V regulator from the original circuit (circa +/-4V). However, when I powered it up it would only give circa 25% of the fullscale deflection. When the test audio signals were applied, the pro-rata decrease in readings appeared to be about right, which was some encouragement.

I subsequently went through everything, and it all seems in order, the notch filter is nice and sharp and the input stage controls the gain nicely. The output from the rectifier hits the supply rail (more or less) in the positive direction and not quite in the other. So I was a little mystified. I checked the fsd of the meter and it is 1mA. Going into mild desperation mode increasing the supply to circa 15V (to give circa +/- 7.5V), then reducing the 6.8k resistors gave a greater scale reading, but not in a linear fashion. Now this is not nice, but in desperation they went dowm to 680 ohms and this gave just over fsd. I suspect the output stage of the op-amp is limiting the current, the datasheet states it is short circuit protected, hence daring to go so low with the resistors. Bodgery I know but I only want to try to get a feel.

I was wondering if the meters actually are supposed to be 1mA, as the one I received had a different scale.

Cheers

Ian.
sentinel040 is offline   Reply With Quote
Old 24th Sep 2022, 3:38 pm   #25
megasounds
Diode
 
Join Date: Aug 2022
Location: Nieuw-Vennep, Netherlands.
Posts: 3
Default Re: SINAD Meter - Home Made for 15.

Quote:
Originally Posted by megasounds View Post
Attachment 264773
Finally built the Ramsey Electronics version. Works great!

PD9MWO
Finished !
Click image for larger version

Name:	sinad.jpg
Views:	12
Size:	84.2 KB
ID:	265235
megasounds is offline   Reply With Quote
Reply

Thread Tools



All times are GMT. The time now is 3:22 pm.


All information and advice on this forum is subject to the WARNING AND DISCLAIMER located at https://www.vintage-radio.net/rules.html.
Failure to heed this warning may result in death or serious injury to yourself and/or others.


Powered by vBulletin®
Copyright ©2000 - 2022, vBulletin Solutions, Inc.
Copyright ©2002 - 2021, Paul Stenning.