Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Parts Where to get, and how to make the best bits. PCB's, caps, transformers, etc.

Relay based volume controls on ebay
Relay based volume controls on ebay
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 19th January 2018, 06:40 PM   #11
mchambin is online now mchambin  France
diyAudio Member
 
Join Date: Mar 2011
Quote:
Originally Posted by Nico Ras View Post
Spikes in switching results in blown tweeters. The worst spikes is when switching three (or more) relays off and one one. If it is a powerful amplifier expect powerful narrow spikes. Unless the system is designed around make-before-break concept.
I see 8 relays to make 256 levels. That is binary coding. It will make a glitch when switching regardless off make before break or break before make. Whatever, there is no way to avoid wrong codes at switching.
__________________
Transistor junction temperature is not transistor case temperature.
  Reply With Quote
Old 20th January 2018, 12:33 PM   #12
IDM is offline IDM  United Kingdom
diyAudio Member
 
Join Date: Apr 2005
Location: Newcastle upon Tyne
The advert says 126 steps. So I wonder if the 8th relay might be a mute to prevent the noise on switching?
  Reply With Quote
Old 20th January 2018, 02:41 PM   #13
IDM is offline IDM  United Kingdom
diyAudio Member
 
Join Date: Apr 2005
Location: Newcastle upon Tyne
Sorry that should have been 128 steps!
  Reply With Quote
Old 8th February 2018, 10:41 AM   #14
IDM is offline IDM  United Kingdom
diyAudio Member
 
Join Date: Apr 2005
Location: Newcastle upon Tyne
I have just tried one of these:
Advanced relay volume control board / HIFI volume board / relay volume board | eBay

When inserted into my 2P29L based pre-amp there was no switching noise, except for one position which was at about 2-3 oclock on the dial. This didn't seem to bad to me as I would anticipate the system to be deafening by this point! So that was good.

When I played music through it, certainly not bad at all (I haven't had time to give it critical listening). Still I am encouraged.

The big issue I have had so far are the steps. I cannot get beyond the first 6-10 steps out of 256 before the volume is ludicrously high! I guess I need to change the resistor values to provide a decent range. However, I haven't yet fathomed the switching order to work which to change and to what value.

Any thoughts?

Cheers
Ian
  Reply With Quote
Old 8th February 2018, 11:54 AM   #15
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
The simplest remedy would be to provide additional attenuation until you get a more usable range
__________________
Woofer Assisted Wideband is the New Testament renounce the anachronistic acronym FAST
  Reply With Quote
Old 8th February 2018, 05:06 PM   #16
stocktrader200 is offline stocktrader200  Canada
diyAudio Member
 
Join Date: Jan 2008
Location: Calgary
I did a volume control using CD4066 switches for 1024 steps. I had to logarithmically adjust the counter to get smooth volume. sounded great with no switching noise
  Reply With Quote
Old 14th February 2018, 08:00 AM   #17
IDM is offline IDM  United Kingdom
diyAudio Member
 
Join Date: Apr 2005
Location: Newcastle upon Tyne
I did some measurements for the input and output resistance. So far I have only measured the first 30 steps or so. The graph looks like the image below. The output resistance is around 300 ohms. If I advance the control a lot it eventually peaks at about 47K, but only for a few settings. The input resistance varies considerably, but on some settings goes as low as 300 ohms. I am no expert but 300 ohms seems far too low to be driven properly.

The resistors are through hole, so they could be replaced. Problem is I am not sure how it has been configured. I will try and trace the wiring.

Any thoughts on the values or how to correct?
Attached Images
File Type: png relay attenuator.png (12.5 KB, 139 views)
  Reply With Quote
Old 14th February 2018, 09:30 AM   #18
shanghai2004 is offline shanghai2004  Taiwan
diyAudio Member
 
Join Date: Apr 2012
Location: Taipei
Relay based volume controls on ebay
Looks indeed not good.

After you figured out the diagram of the device you have, use this to find the correct resistor values:

Logarithmic Attenuator Calculator
  Reply With Quote
Old 14th February 2018, 09:42 AM   #19
scottjoplin is offline scottjoplin  Wales
diyAudio Member
 
scottjoplin's Avatar
 
Join Date: Dec 2015
Location: Penrhyndeudraeth
When measuring the resistances how are you connecting your multimeter? Do you have anything connected to the input or output?
__________________
Woofer Assisted Wideband is the New Testament renounce the anachronistic acronym FAST
  Reply With Quote
Old 14th February 2018, 10:12 AM   #20
IDM is offline IDM  United Kingdom
diyAudio Member
 
Join Date: Apr 2005
Location: Newcastle upon Tyne
When measuring, I disconnected the board from the pre-amp, so it wasn't affected by the grid leak resistor. I then put the multimeter either between ground and one channel input for input resistance or ground and output to measure output resistance. I also measured series resistance by measuring from input to output.
  Reply With Quote

Reply


Relay based volume controls on ebayHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
AC induction controls low power relay? cuibono Power Supplies 1 10th November 2013 05:55 PM
Volume Controls KatieandDad Analogue Source 10 21st November 2011 08:38 PM
Volume Controls Glowin Plates Tubes / Valves 8 8th April 2011 02:42 AM
sound quality of relay volume controls VS resistive stepped attenuators jarthel Parts 1 10th October 2006 02:40 PM
Relay-based passive volume control project BrianGT Everything Else 110 1st March 2003 01:27 AM


New To Site? Need Help?

All times are GMT. The time now is 06:23 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki