Lm1875, Bill Of Components

alcuemar · 24th May 2006, 10:54 AM

Dear friends,

I have some doubts about component characteristics, I have doubts in resistors R1 to R5 power, tolerance and type!! And for capacitors the same C1 to C7, type, tolerance, voltage, ...

What is the maximum speaker power that I can use in the output (ohms and power)?

And for end, What components I can remove from the original circuit?

My very best thanks for all the group!!

Alcuemar

pinkmouse · 24th May 2006, 10:57 AM

Which schematic?

alcuemar · 24th May 2006, 11:04 AM

Hi,

The schematic showed in the first page from the LM1875 datasheet.

Alcuemar

elementx · 24th May 2006, 06:12 PM

I'll tell you a big secret... You can use just about anything on these chips. Any little resistors, 1/4 or 1/2 watt, 5% or 10%, it really doesn't matter. It's low power, low voltage, just get as close to those values as you can.

Use caps rated higher then whatever voltage you're putting into the chip...

don't overthink it! have fun and experiment...

edl · 24th May 2006, 08:35 PM

Dear Alcuemar,

All resistors are 0.5/0.6W 1% metal film.
C1 is an 50V elko, or a 63/100V foil cap.
C2 is an 16V elko, or a 25V bipolar elko.
C3 and C4 are 63/100V foil caps.
C6 and C6 are 35V elkos.
C5 is a 63/100V foil cap.

Output pwr is about 25 Watts.

What components to remove? Nothing. Build exactly the datasheet's circut.

Best regards,

theChris · 25th May 2006, 03:50 AM

it is my understanding that this is a commercial project.

in anycase, use ohm's law and power law -- P = V^2 / R.

keep in mind that to get 0.25W into a 1kOhm load you need approximately 16V across the resistor. for 10k resistors you would need 160V.

so at the low voltages, it almost certain that you will have no issues with the large resistors.

tolerance likewise is based upon the equations. the gain equation will show the maximum deviation of gain. this can be used for the left and right channel and you can find how much louder the "maximum gain" would be compared to the "minimum gain". where maximum and minimum are due to the component tolerances.

alcuemar · 25th May 2006, 07:42 AM

Why is the reason to put a 1ohm resistor (R5) and one cap 0.22uF (c5) in paralell with the output (speaker)? Anyone know it?

testlab · 25th May 2006, 11:47 AM

The r/c on the output, is a low pass filter. It helps to keep load reactances and voice coil back-emf, from making the amplifier oscillate.

edl · 25th May 2006, 11:55 AM

That'sa Boucherot-cell. Don't remove it!

alcuemar · 25th May 2006, 12:03 PM

Thanks to all for the explication!!!!!!!!

24th May 2006, 10:54 AM	#1
alcuemar diyAudio Member Join Date: May 2006	Lm1875, Bill Of Components Dear friends, I have some doubts about component characteristics, I have doubts in resistors R1 to R5 power, tolerance and type!! And for capacitors the same C1 to C7, type, tolerance, voltage, ... What is the maximum speaker power that I can use in the output (ohms and power)? And for end, What components I can remove from the original circuit? My very best thanks for all the group!! Alcuemar

24th May 2006, 10:57 AM	#2
pinkmouse diyAudio Moderator Join Date: Apr 2002 Location: Chatham, England	Which schematic? __________________ Al I conceive of nothing, in religion, science or philosophy, that is more than the proper thing to wear, for a while. Charles Fort

25th May 2006, 03:50 AM	#6
theChris diyAudio Member Join Date: Dec 2001 Location: SIUE, Illinois, USA	it is my understanding that this is a commercial project. in anycase, use ohm's law and power law -- P = V^2 / R. keep in mind that to get 0.25W into a 1kOhm load you need approximately 16V across the resistor. for 10k resistors you would need 160V. so at the low voltages, it almost certain that you will have no issues with the large resistors. tolerance likewise is based upon the equations. the gain equation will show the maximum deviation of gain. this can be used for the left and right channel and you can find how much louder the "maximum gain" would be compared to the "minimum gain". where maximum and minimum are due to the component tolerances. __________________ if only it could be used for good, not evil...

25th May 2006, 11:47 AM	#8
testlab diyAudio Member Join Date: Dec 2005 Location: Grand Rapids MI	The r/c on the output, is a low pass filter. It helps to keep load reactances and voice coil back-emf, from making the amplifier oscillate. __________________ It's not whether you win or lose, it's how you lay the blame.

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24th May 2006, 11:04 AM	#3
alcuemar diyAudio Member Join Date: May 2006	Hi, The schematic showed in the first page from the LM1875 datasheet. Alcuemar

24th May 2006, 06:12 PM	#4
elementx diyAudio Member Join Date: Jul 2005 Location: cleveland, ohio	I'll tell you a big secret... You can use just about anything on these chips. Any little resistors, 1/4 or 1/2 watt, 5% or 10%, it really doesn't matter. It's low power, low voltage, just get as close to those values as you can. Use caps rated higher then whatever voltage you're putting into the chip... don't overthink it! have fun and experiment...

24th May 2006, 08:35 PM	#5
edl diyAudio Member Join Date: Oct 2004	Dear Alcuemar, All resistors are 0.5/0.6W 1% metal film. C1 is an 50V elko, or a 63/100V foil cap. C2 is an 16V elko, or a 25V bipolar elko. C3 and C4 are 63/100V foil caps. C6 and C6 are 35V elkos. C5 is a 63/100V foil cap. Output pwr is about 25 Watts. What components to remove? Nothing. Build exactly the datasheet's circut. Best regards,

25th May 2006, 07:42 AM	#7
alcuemar diyAudio Member Join Date: May 2006	Why is the reason to put a 1ohm resistor (R5) and one cap 0.22uF (c5) in paralell with the output (speaker)? Anyone know it?

25th May 2006, 11:55 AM	#9
edl diyAudio Member Join Date: Oct 2004	That'sa Boucherot-cell. Don't remove it!

25th May 2006, 12:03 PM	#10
alcuemar diyAudio Member Join Date: May 2006	Thanks to all for the explication!!!!!!!!

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