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Old 19th December 2009, 07:48 AM   #21
pra3718 is offline pra3718  India
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Quote:
The TDA7294 will work with pins 9 and 10 floating or connected to ground. You do not need the resistors and capacitors. The drawback is that you may experience pop noises, when powering the amp up, when you don't use those components.
Pb, I found, if I don't use / floating pin 9 and 10, amp does not sound.
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Old 19th December 2009, 10:11 AM   #22
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Yes, I corrected myself in post #16. Pins 9 and 10 need a voltage of 3,5 V or higher. You can connect them to the positive rail.
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Old 19th December 2009, 02:25 PM   #23
pra3718 is offline pra3718  India
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pacificblue, As I learn, If I increase resister & Cap value, It would increase ON/OFF time. Lets take a example for MUTE Pin # 10 default value 10K & 10uf. If I increase the value by 22K & 22uf On/Off time would increase and I would reach the value of ST-BY TIME. If the both Resister & Cap is same then why two resistor & two caps are required ? I would select one Resister attach to PIN # 9 & 10 and another end attach to PIN # 13. (In addition with 22uf cap) What do you think ? Is there any specific reason to keep both Resistor & Caps separate ?
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Old 19th December 2009, 02:40 PM   #24
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Originally Posted by pra3718 View Post
Is there any specific reason to keep both Resistor & Caps separate ?
Mute serves an input function. The mute doesn't require a capacitor; however a 10k resistor is a good idea.

Standby serves an output function. You'll want to have your standby with both resistor and capacitor (for time delay). This capacitor can be 10uF 50v, which are a conveniently small size. The resistor can be 22k.

There is what I believe to be the minimum (3) components.

Edit: If either mute or standby pin happens to break off, you may fuse them together as a repair; however, the amplifier's performance is slightly reduced when mute and standby pins are directly connected together. Its Not recommendable to connect the two directly.

Last edited by danielwritesbac; 19th December 2009 at 02:45 PM.
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Old 20th December 2009, 10:29 AM   #25
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Stand-by is used to waste less energy, when the amplifier is not used during a longer period of time. You would waste even less energy switching the amplifier completely off. The drawback is that cycling the power puts stress on many components. Therefore some people prefer(ed) to waste a little more power in return for longer component life. The stand-by delay avoids popping noises or DC components during the charging time of the power supply. Popping may only be annoying or can destroy tweeters. DC components can become visible, when the woofer cone moves away from its center position and remains there, and can even destroy woofers. That is, why the stand-by had better be delayed.

Mute is used to switch the amplifier off for a short period of time, e. g. when you have to answer the phone. If you switch the amplifier off or to stand-by during that time, it will cool off. Some amplifiers, when heating up pass through a period of worsened sonic performance until all components have reached their thermal equilibrium. To avoid that, you mute the amplifier.

You can switch both inputs at the same time, if you have no need for the mute function. Negative sonic effects are not likely. The datasheet shows on page 9 how to make a start-up sequence with a single signal designed for a signal level of 5 V. You can use the positive rail-voltage directly, which will reduce the start-up time, so you may have to increase the resistor values accordingly.
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Old 20th December 2009, 10:57 AM   #26
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Well, instead of an awful mess, howabout this?:
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Old 23rd December 2009, 09:11 AM   #27
pra3718 is offline pra3718  India
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As per attached picture OPTION 1 would work. But what about OPTION 2 ?
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Old 23rd December 2009, 02:02 PM   #28
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Option 2 should work as well.
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Old 27th December 2009, 06:17 PM   #29
sexya is offline sexya  India
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Default check this layout

hii
i have made this layout, most part may be in haste, but i dont have the patiance to make it more ashetical,
i m puting a top view in colour with a component silk screen,
guys replay to this asap please,
i plan to toner transfer the pcb tomor.
the feed back resistor which is behind th chip is actualy below the board on the solder side,
and i have used diode parrallel to resistor for standby section which is coming next to the filter caps,
thanks
with regards
aditya
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Old 2nd January 2010, 04:16 AM   #30
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Double check the polarity orientation of the 2 big power caps. V- = pin15

The Mute appears to be hooked up to nothing; however, your board is workable because one could omit that cap and quite easily install a 10k resistor from V+ to pin 10 with the pads already provided by the board. That resistor would either be an 1/8w or a 1/4w that would "stand up." But its workable.

I kind of like your board--its much easier to solder than these:
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