Need help with DC follower/peak follower HELP! - diyAudio
Go Back   Home > Forums > Design & Build > Parts

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

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 26th June 2008, 05:46 PM   #1
diyAudio Member
 
gain wire's Avatar
 
Join Date: Nov 2004
Location: NCR
Unhappy Need help with DC follower/peak follower HELP!

Hi,
I am trying to build a DC follower/peak follower. It is my "design" so far, but so far the darn circuit isn't working like I want it to work. The goal is to have this op-amp (see attached file) take an AC signal and extract the DC component. THIS SHOULD BE SIMPLE! It amplifies an incoming AC signal, let's say for simplicity purpose, a 1kHz wave) and amplify by two, then rectify it with diode, filtering out any residual AC with the 220uF capacitor. Simple enough right? THIS SHOULD BE SIMPLE, YET IT AIN'T WORKING!

Well it doesn't rectify! I tried other diodes, I tried other capacitors, I tried even with different discharge resistors. The only time it ever works, sort of, is when I raise the value of the discharge resistor to about 200Kohms. When I vary my input signal's amplitude, then I get a corresponding DC level , which is what I want, but it keeps drifting back to a common DC level.

Any help? Please! I feel so stupid...
Attached Images
File Type: jpg dc_follower.jpg (19.9 KB, 53 views)
__________________
Trans-directional-servo-logamp non-zerocrossing autogain compressing thingamajig
  Reply With Quote
Old 28th June 2008, 05:32 PM   #2
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
dual polarity PSU
__________________
regards Andrew T.
  Reply With Quote
Old 28th June 2008, 05:57 PM   #3
diyAudio Member
 
gain wire's Avatar
 
Join Date: Nov 2004
Location: NCR
What? you mean use a dual polarity supply will suddenly make this work? Could you explain? I don't get it...
Really I don't see why, because I am already supplying the positive input with a bias voltage of 4 volts.
How will it help if the supply is bipolar?
Thanks.
__________________
Trans-directional-servo-logamp non-zerocrossing autogain compressing thingamajig
  Reply With Quote
Old 28th June 2008, 06:08 PM   #4
AndrewT is online now AndrewT  Scotland
diyAudio Member
 
Join Date: Jul 2004
Location: Scottish Borders
eliminate the 4.5V of output offset.
__________________
regards Andrew T.
  Reply With Quote
Old 8th July 2008, 03:32 PM   #5
udailey is offline udailey  United States
diyAudio Member
 
Join Date: Mar 2008
Gainwire,
I was in the forum and saw you needed old pots. It wont let me respond or email you. Email me and I will give you a list of Duncan Electronics, Helipot, and General Radio Corp pots.
Sorry for OT guys.
Uriah
  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
Hot follower/cool follower webercarbmann Solid State 13 2nd November 2010 02:23 PM
Hot Follower 99 MEGA_amp Solid State 25 7th March 2010 08:00 PM
Question about direct coupling a anode follower into a cathode follower. G Tubes / Valves 45 29th July 2004 06:47 PM
ZEN v4 -> follower Stefano Pass Labs 7 14th June 2004 06:29 PM
hot follower UrSv Pass Labs 2 25th September 2002 04:49 PM


New To Site? Need Help?

All times are GMT. The time now is 04:34 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