How do autoformer impedance matching controls work - diyAudio
 How do autoformer impedance matching controls work
 User Name Stay logged in? Password
 Home Forums Rules Articles diyAudio Store Gallery Wiki Blogs Register Donations FAQ Calendar Search Today's Posts Mark Forums Read Search

 Solid State Talk all about solid state amplification.

 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
 11th March 2005, 06:41 AM #1 diyAudio Member   Join Date: Mar 2005 Location: WI How do autoformer impedance matching controls work I am in desperate need to understand how an autoformer based volume control works. Ideally, I would like to get my hands on a schematic. I helped a friend install four volume controls (installed in parallel using the x4 setting to present a combined 8ohm load). I am however perplexed how these controls work and need to understand to resolve a problem. Any help is greatly appreciated. Thanks.
 11th March 2005, 07:21 AM #2 diyAudio Member   Join Date: Jul 2004 Location: Scottish Borders Hi, the autotransformer will do both impedance matching and volume control. Which do you need? For a volume control the autoT can provide either gain or attenuation or a range of both. Consider an autoT with 5 wires; start, 25%, 50%, 75% and finish. Connect the input to start and finish then the output can be connected to any pair but with no gain available. eg. output s/25% gives -12db. s/50% gives -6db, s/75% gives -2.5db, s/f gives 0db. The formula is 20 * log(volt gain). If volt gain is less than 1 then the log will be negative. If you need to specify the transformer tappings then the reverse formula can be applied using the 10^x key on your calculator. If you connect the input to s/50% then you can get gain (2 tappings) and attenuation. For impedance conversion use the (volt gain ^2) * impedance to give the new impedance. Maybe that is what you want, I hope I'm not trying to teach you have to suck eggs, Sorry if I have. __________________ regards Andrew T. Sent from my desktop computer using a keyboard
diyAudio Member

Join Date: Oct 2002
Location: Croatia
http://www.rane.com/note136.html

my little calculation:
Attached Images
 autotr.jpg (48.5 KB, 292 views)

 12th March 2005, 07:51 AM #4 diyAudio Member   Join Date: Mar 2005 Location: WI Thank you. The wiring diagram provided is what I was looking to obtain. Much appreciated!!!

 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 OffTrackbacks are Off Pingbacks are Off Refbacks are Off Forum Rules

 Similar Threads Thread Thread Starter Forum Replies Last Post Triod lover Tubes / Valves 2 12th January 2007 09:59 AM MyNameIsJake Solid State 2 4th June 2006 05:32 PM percy Tubes / Valves 5 28th February 2005 08:35 PM fragman56 Tubes / Valves 17 20th March 2003 02:38 PM bryce66 Solid State 6 9th November 2001 09:02 AM

 New To Site? Need Help?

All times are GMT. The time now is 02:50 PM.