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View Poll Results: Was a good idea to use two lm1875 or a big stk chip
Use stk 8 27.59%
use lm1875 21 72.41%
Voters: 29. You may not vote on this poll

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Old 16th February 2013, 04:15 PM   #221
JMFahey is offline JMFahey  Argentina
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Join Date: Mar 2009
Location: Buenos Aires - Argentina
Quote:
Originally Posted by PetruV View Post
just saw an old project i made called the relay amp,
It was an amp with 3 relays one at 24v on at 12 and one at 5.
Each rellay was triggered at a different voltage and made up a horrible sounding but very powerful amp.
I this worth Souping up with 200-300 relays or low rds mosfets each at different voltage,will it sound harsh or not?
You just made it up so people answers you.
Even somebody telling you this is madness will make you happy.
As in "Hey !!, maybe I can get another 200 or 300 replies on this mad project !!!"
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Old 17th February 2013, 07:05 PM   #222
PetruV is offline PetruV  Romania
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Join Date: Dec 2012
Location: Bucuresti
Sorry guys for being rude,i didnt want to be so bu i have mental issues,and im not lying,I will be more calm amd more focused now,i you lease forgive me,please
I didnt write that up for no reason i was just curious if its possible.
one of my lm1875ts has its output stuck to v+,what could be the problem? :

Also i got one my tda2003 working,but one not working,very quiet pop on off on the non working one and then verry weak and distorted audio out of that but from the othe the audio is perfect almost as good as lm1875 when it sorta worked.
I know the rellay amp is very complicate and ridiculous but i would be nearly 100% efficent if i use relays

Last edited by PetruV; 17th February 2013 at 07:09 PM.
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Old 18th February 2013, 08:04 AM   #223
PetruV is offline PetruV  Romania
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Join Date: Dec 2012
Location: Bucuresti
OOoo look what i found,could thos gan fet things be used for audio amplifier ,they have low rds on which is good for d amps.
Anyways i thought about the relay amp and is impossible,but if i use a high speed solid state relay and a class d driver i may get what i want.

Here are those gan fets

Benefits of TI GaN FET driver solutions:
  • Increased power density
  • Maximizes dV/dt immunity, prevents accidental low-side turn-on
  • Independent source/sink pins optimize turn-on and turn-off times to enhance efficiency and reduce noise
Challenges of GaN FETs:
  • Low threshold voltage
  • Stringent gate-source voltage drive requirements
  • Need to limit high-side FET to 6V
  • Prevent erratic switching behavior with high dV/dt transients
Benefits of GaN FETs:
  • Much lower Rdson and Qg
  • Higher input voltages
  • Greater efficiencies
  • Faster switching frequencies
  • Ultra-small package footprint for higher density power converters
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Old 18th February 2013, 09:45 AM   #224
PetruV is offline PetruV  Romania
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Join Date: Dec 2012
Location: Bucuresti
Help me,my old and crappy living room pc is making high pitch continuous squel trough my usb powered tda 2003,which on my laptom only has a slight hiss,and on my other desktop no noises at all.
Ocasionaly the sound stop for a sec or two and sometimes it changes pitch,it is not dependat from computers volume,and the tda 2003 has no vollume control
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Old 19th February 2013, 05:29 PM   #225
picbuck is offline picbuck  United States
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<< it took me 2 hours to solder all that crap in cause my soldering iron sucks and i never used perfboard >>

Your soldering iron is fine. It took you 2 hours because you believed the fairy tale about flux-core solder being all you need.

It's not. Use 1/32" solder and Ignore the flux core. Use a general-purpose flux like Radio Shack's, or you can get it on eBay. A tin of flux will probably last you a lifetime.

From a plastic milk carton or such, cut an applicator(s). Big enough for your hand to hold, but with a smallish point for applying flux. Not too smallish. Back in the tube days techs used to say "there's no such thing as too much flux," and the rule still applies.

Technically you're supposed to clean off the the flux residue when you're done soldering--although many don't. If you do (which is certainly good practice), either mineral spirits or alcohol will do the job. Both are available in quarts from Home BigBox. Real denatured alcohol, not the stuff from the drugstore. The universal cleaning tool is an old toothbrush.

If you can't tell, people trying to solder without using flux is a pet peeve of mine. The last thing you need to do is spend $200 for what marketers call a "soldering station." Unless you like that kind of thing, of course. But all you really need is flux, and to wait untl the iron gets hot. It's hot when it instantly melts the solder you apply to test.

Oh yes! When you're soldering pots try not to let a lot of flux run down into the works. Try to solder pots with the contacts pointing down.
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Old 20th February 2013, 08:41 AM   #226
PetruV is offline PetruV  Romania
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Join Date: Dec 2012
Location: Bucuresti
Quote:
Originally Posted by picbuck View Post
<< it took me 2 hours to solder all that crap in cause my soldering iron sucks and i never used perfboard >>

Your soldering iron is fine. It took you 2 hours because you believed the fairy tale about flux-core solder being all you need.

It's not. Use 1/32" solder and Ignore the flux core. Use a general-purpose flux like Radio Shack's, or you can get it on eBay. A tin of flux will probably last you a lifetime.

From a plastic milk carton or such, cut an applicator(s). Big enough for your hand to hold, but with a smallish point for applying flux. Not too smallish. Back in the tube days techs used to say "there's no such thing as too much flux," and the rule still applies.

Technically you're supposed to clean off the the flux residue when you're done soldering--although many don't. If you do (which is certainly good practice), either mineral spirits or alcohol will do the job. Both are available in quarts from Home BigBox. Real denatured alcohol, not the stuff from the drugstore. The universal cleaning tool is an old toothbrush.

If you can't tell, people trying to solder without using flux is a pet peeve of mine. The last thing you need to do is spend $200 for what marketers call a "soldering station." Unless you like that kind of thing, of course. But all you really need is flux, and to wait untl the iron gets hot. It's hot when it instantly melts the solder you apply to test.

Oh yes! When you're soldering pots try not to let a lot of flux run down into the works. Try to solder pots with the contacts pointing down.
I used a crappy old solder gun which each 5 mins of use had to sit half an hour to cool donw its transformer,
No i have a very big soldering iron(15 inches long)Which had a tip as thick as my thumb,so i sharpenend it with a file and now i can even solder smd parts
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Old 21st February 2013, 05:20 PM   #227
PetruV is offline PetruV  Romania
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Join Date: Dec 2012
Location: Bucuresti
I seems as more than half of the people wanted me to use lm1875 not stk so it seems as i made a wise choice
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Old 21st February 2013, 09:00 PM   #228
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Join Date: Apr 2007
Yes, now you should focus on SMPS and linear ...
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Old 22nd February 2013, 10:33 AM   #229
PetruV is offline PetruV  Romania
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Join Date: Dec 2012
Location: Bucuresti
Im building two apex b500 now with rewound mots since they are cheap,but i need to go to someone who has laser printer,and then buy the parts and mots and rewind them and give the weak lm1875 to my mom to use in her room.BUT firest i have to find why its output is stuck to v+ but i cant test it since i lost its plug adapter
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Old 23rd February 2013, 07:58 AM   #230
PetruV is offline PetruV  Romania
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Join Date: Dec 2012
Location: Bucuresti
Quote:
Originally Posted by picbuck View Post
<< it took me 2 hours to solder all that crap in cause my soldering iron sucks and i never used perfboard >>

Your soldering iron is fine. It took you 2 hours because you believed the fairy tale about flux-core solder being all you need.

It's not. Use 1/32" solder and Ignore the flux core. Use a general-purpose flux like Radio Shack's, or you can get it on eBay. A tin of flux will probably last you a lifetime.

From a plastic milk carton or such, cut an applicator(s). Big enough for your hand to hold, but with a smallish point for applying flux. Not too smallish. Back in the tube days techs used to say "there's no such thing as too much flux," and the rule still applies.
I have switched to solder with no flux at all and everithing seems better now

Technically you're supposed to clean off the the flux residue when you're done soldering--although many don't. If you do (which is certainly good practice), either mineral spirits or alcohol will do the job. Both are available in quarts from Home BigBox. Real denatured alcohol, not the stuff from the drugstore. The universal cleaning tool is an old toothbrush.

If you can't tell, people trying to solder without using flux is a pet peeve of mine. The last thing you need to do is spend $200 for what marketers call a "soldering station." Unless you like that kind of thing, of course. But all you really need is flux, and to wait untl the iron gets hot. It's hot when it instantly melts the solder you apply to test.

Oh yes! When you're soldering pots try not to let a lot of flux run down into the works. Try to solder pots with the contacts pointing down.
I have switched to no flux at all and everithing is now better

Last edited by PetruV; 23rd February 2013 at 08:01 AM.
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