a very simple speaker protect just for class-d

fumac · 18th January 2007, 02:41 AM

a very simple speaker protect just for class-d
when the PWM is off, it turn off the speaker
r3 is wrong del it

fumac · 18th January 2007, 02:58 AM

D3 pls use 4001,is better than 4148

Pierre · 18th January 2007, 05:16 AM

I assume that will be connected to the mosfets switching output, right?
It is very smart, but have you tested that it triggers when there is PWM but it has a fixed duty cycle, different from 50%, that produces DC at the output that is dangerous enough for the speakers?
In that situation, the circuit should also trigger. This is unlikely and not related to output mosfet failure, but...

fredos · 18th January 2007, 03:37 PM

What I see Pierre is that he just try to mute output with a relay when there is no PWM signal...No protection at all here, just a mute..

Fredos

www.d-amp.com

RX5 · 19th January 2007, 02:00 AM

mute function for PS

Eva · 19th January 2007, 10:29 AM

It seems more like a mute function in case of a blown output stage.

fumac · 19th January 2007, 11:02 AM

wellcome all
this sch just like a mute function
but it's allmost can protect ur speaker connet to ucd or ucd_like amp
it base on the great design of ucd,

i'll post some pics
to say it clearly

it depend on :when the pwm is off, it will take the speaker off the power amp

1.when ur fet are break,the pwm will be off
2. when ur input connet to the VDD(+50V), the output about 10v dc,and the pwm will be off
3. when daul the power is not the same No. dont worry that.

fumac · 19th January 2007, 11:12 AM

this pic is that the input short to vdd,and the power output 10vDC,
if ur have no protec ur speaker will have a 1~2A DC

the sch will take an action, bcs,the pwm is off

fumac · 19th January 2007, 12:01 PM

this pic is when the power is +50v -25v
ucd is a great design, it can work on +50v -25v!
and the dc offset just +2v , it can't burn ur speakers
and u can hear the dis is very large,
this is a very Extreme State¡£

when the power is +50v -15v, the offset is 3v.
when the power is +50v -10v, the offset is 3.5v.
when the power is +50v -8v, the offset is 3.6v.
when the power is +50v -5v, the pwm is off

this is like that one of the FET is being Death (i dont know how to say it in english

)

fumac · 19th January 2007, 12:23 PM

but sometimes it cant protect.
if u connet a 30k from input to vdd.
the pwm is on,but the output offset is 10v, is ham to ur speaker.
so, u must to insert a cap on the input pin.

19th January 2007, 02:00 AM	#5
RX5 diyAudio Member Join Date: Apr 2004 Location: TaC	mute function for PS __________________ RoCk On!!! I love my diy UcD!!

19th January 2007, 10:29 AM	#6
Eva diyAudio Member Join Date: Oct 2003 Location: Near the sea	It seems more like a mute function in case of a blown output stage. __________________ I use to feel like the small child in The Emperor's New Clothes tale

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18th January 2007, 02:58 AM	#2
fumac diyAudio Member Join Date: Oct 2006	D3 pls use 4001,is better than 4148

18th January 2007, 05:16 AM	#3
Pierre Banned Join Date: Nov 2004 Location: Paris	I assume that will be connected to the mosfets switching output, right? It is very smart, but have you tested that it triggers when there is PWM but it has a fixed duty cycle, different from 50%, that produces DC at the output that is dangerous enough for the speakers? In that situation, the circuit should also trigger. This is unlikely and not related to output mosfet failure, but...

18th January 2007, 03:37 PM	#4
fredos diyAudio Member Join Date: Mar 2005 Location: Quebec	What I see Pierre is that he just try to mute output with a relay when there is no PWM signal...No protection at all here, just a mute.. Fredos www.d-amp.com

19th January 2007, 11:02 AM	#7
fumac diyAudio Member Join Date: Oct 2006	wellcome all this sch just like a mute function but it's allmost can protect ur speaker connet to ucd or ucd_like amp it base on the great design of ucd, i'll post some pics to say it clearly it depend on :when the pwm is off, it will take the speaker off the power amp 1.when ur fet are break,the pwm will be off 2. when ur input connet to the VDD(+50V), the output about 10v dc,and the pwm will be off 3. when daul the power is not the same No. dont worry that.

19th January 2007, 12:23 PM	#10
fumac diyAudio Member Join Date: Oct 2006	but sometimes it cant protect. if u connet a 30k from input to vdd. the pwm is on,but the output offset is 10v, is ham to ur speaker. so, u must to insert a cap on the input pin.

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