Amp newbie attempting project - Page 3 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 22nd December 2012, 09:15 AM   #21
diyAudio Member
 
Join Date: Nov 2012
Alright well I just went ahead and bought both 470uF and a 6800uF (what was on hand) cheapo electrolytic caps. Yes I have read these are terrible to put in the signal path but for testing they are equally terrible and adequate. I noticed very little difference between the two caps on this setup which proves to me its fine.

One unintended thing... it picks up the oldies station with a 3.5mm plugged in.

Last edited by ForeverSka; 22nd December 2012 at 09:28 AM.
  Reply With Quote
Old 22nd December 2012, 09:32 AM   #22
diyAudio Member
 
sofaspud's Avatar
 
Join Date: Nov 2005
Location: San Antonio
You don't like oldies?
The filter doesn't have to be that low. Try the handiest picofarad cap you have. Was anything connected to the other end of the plug? If not it'd be more likely to act as an antenna.
Remember also that if you decide on the bridged circuit the series output cap is a moot point.
__________________
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
  Reply With Quote
Old 22nd December 2012, 09:41 AM   #23
diyAudio Member
 
Join Date: Nov 2012
Yea connected or not I got the radio station. A little bit of volume on the computer and it would mask it but the second it went quiet I could hear a quiet rendition of "Thriller". I'll grab a little pF cap tomorrow and give it a go.

The final build will be an auto grade 50W Toshiba chip amp. Just ironing out the theory before I order one of those. Burnt one chip so far so its a good thing.
  Reply With Quote
Old 22nd December 2012, 08:16 PM   #24
diyAudio Member
 
Join Date: May 2008
Add the RF snubber to the output as per datasheet, i.e. 2,7 Ohm resistor in series with 100 nF capacitor from IC pin 8 to ground.
__________________
If you've always done it like that, then it's probably wrong. (Henry Ford)
  Reply With Quote
Old 27th December 2012, 08:42 AM   #25
diyAudio Member
 
Join Date: Nov 2012
So I tried an RF snubber tonight. It kinda just adds a TON of noise... I mean you cant hear the RF anymore because of the chainsaw noise but that's hardly the effect I was thinking. How sensitive is this circuit? With resistors on hand I can do 2.2 ohm and 2.8 ohm (pair of 5.6 in parallel) but neither sound anywhere near good. Me being near it makes it worse so somehow my snubber is causing more EMI interference?
  Reply With Quote
Old 27th December 2012, 09:18 AM   #26
diyAudio Member
 
sofaspud's Avatar
 
Join Date: Nov 2005
Location: San Antonio
Can you post a picture of your circuit?
__________________
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine
  Reply With Quote
Old 27th December 2012, 09:42 AM   #27
diyAudio Member
 
Join Date: Nov 2012
Messy breadboard but you might just get the idea.
Attached Images
File Type: jpg 2012-12-27 02.33.50.jpg (658.8 KB, 65 views)
File Type: jpg 2012-12-27 02.29.05.jpg (668.2 KB, 60 views)
  Reply With Quote
Old 27th December 2012, 10:24 AM   #28
diyAudio Member
 
sofaspud's Avatar
 
Join Date: Nov 2005
Location: San Antonio
You don't show any input leads. (edit: nevermind that, my navigation was off) Using shielded wire there, and cleaning up the other wiring, is my best suggestion. Long & loopy wires invite RFI.
You could also try the simplest configuration of output capacitor only, verify it, and add to it while testing at each step. That should automatically localize noise and other effects on the circuit.
__________________
It is error only, and not truth, that shrinks from enquiry. - Thomas Paine

Last edited by sofaspud; 27th December 2012 at 10:28 AM.
  Reply With Quote
Old 27th December 2012, 06:24 PM   #29
diyAudio Member
 
Join Date: May 2008
Sounds like you shorted something. Are you sure that electrolytic has 0,1 F aka 100 nF? It should not have 100 F. The usual choice in this place is a ceramic or a film cap.
__________________
If you've always done it like that, then it's probably wrong. (Henry Ford)
  Reply With Quote
Old 20th January 2013, 07:57 AM   #30
diyAudio Member
 
Join Date: Nov 2012
Well at any rate this little chip is a fun science project but it is only 2.5W and even the best of speakers powered at 2.5W will barely overpower a noisy late 60s VW engine. lol

So lets discuss the TDA1557Q. Mouser claims NXP has discontinued this chip with no replacement so is it common to buy them from ebay sellers?

Then pin 12:
I think I've seen this discussed somewhere but hardly remember if an answer was ever offered up. "the harmonic distortion at low frequencies can be decreased by connecting two diodes to ground at pin 12." Can anyone expound on this? I'm imagining going to my local electronics store, picking a couple of their cheapest garden variety diodes off the shelf and hooking them to pin 12 in the direction of ground. Am I close?

Just making sure:
This chip has "speaker protection" so that means I don't need a speaker coupling cap, right?
  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
Newbie amp project power supply noise rory1327 Solid State 7 29th December 2011 06:33 PM
Concrete Sandwich - Cheap & Cheerful Speaker Project (detailed, newbie friendly) jabney Full Range 2 11th October 2011 03:37 AM
Attempting a Chip Amp Build - Need a PCB! deadparrot Chip Amps 7 2nd July 2009 03:14 PM
Newbie trouble- First Amp Project TDA1517 dj_oatmeal Chip Amps 19 1st October 2008 11:56 PM
is this amp good for newbie project?? behnkem Solid State 5 13th March 2003 02:42 AM


New To Site? Need Help?

All times are GMT. The time now is 11:31 AM.


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