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Old 4th November 2004, 12:17 PM   #1
garbage is offline garbage  Singapore
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Default chipamp lm4780 components

hi all

according to the chipamp lm4780 kit, the parts are as follows:

LM4780 Dual Mono Kit Contents
1 PCB set, consisting of 2 amplifier and 2 rectifier boards.
2 LM4780
6 22 kohm 0.5w compact metal film resistors
4 2 kohm 0.5w compact metal film resistors
4 680 ohm 0.5w compact metal film resistors
2 10 kohm 0.5w compact metal film resistors (mute)
4 0.1 ohm 3w Dale LVR3 power resistors (output)
4 2.7 ohm 2w Panasonic metal film resistors (zobel)
4 0.1 uf BC polypropylene cap (zobel)
4 1500 uF 50v Panasonic FC Capacitors
16 MUR860 On Semiconductor Diodes
4 10 uF Panasonic FC Capacitors

but on the pcb i'm not sure which goes where as there is no documentation yet.

can someone confirm the below?

i gather the following information from other threads:
R1 = 22k (feedback resistors)
R2 = 22k (feedback resistors)
R3 = 1k or 680R (for more gain)
R4 = 22k
R5 = 1k or 680R (for more gain)
R6 = 1k or 220R (series input resistors)
R7 = 1k or 220R (series input resistors)
R8 = 0.1R (output)
R9 = 0.1R (output)
Cz1 and Cz2 seems to be the zobel cap.
the holes parallel to Cz1 and Cz2 seems to be the zobel resistors.
C1 and C2 are the 10uF bypass caps or BG 4.7uF N caps.

thanks
garbage

btw, i've got my boards.
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Old 9th November 2004, 12:35 AM   #2
garbage is offline garbage  Singapore
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Unhappy 0R1 accuracy?

have you guys measured the value of the 0R1 resistor?
i measured mine and got fluctuating readings from 0R to 0R8!!

these are the cheap coffin type resistors.

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Old 9th November 2004, 12:44 AM   #3
tiroth is offline tiroth  United States
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You can't measure such low impedances with a standard multimeter. You should run a known current through it and measure the voltage instead.
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Old 9th November 2004, 01:40 AM   #4
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Quote:
Originally posted by tiroth
You can't measure such low impedances with a standard multimeter.
You can do it with a "standard" analog multimeter.
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Old 9th November 2004, 02:37 AM   #5
tiroth is offline tiroth  United States
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What is this "analog" you speak of, good sir?
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Old 9th November 2004, 05:45 PM   #6
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Quote:
Originally posted by tiroth
What is this "analog" you speak of, good sir?
Something like this:
http://www.gmc-instruments.com/engli...metrahit1a.htm
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Old 9th November 2004, 05:52 PM   #7
tiroth is offline tiroth  United States
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I was just joking
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Old 9th November 2004, 06:39 PM   #8
wim is offline wim  Netherlands
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Forget it Carlosfm, you can't measure such low resistances acurate with a standard multimeter (digital or analog) , only with very expensive multimeters, special mili-ohm meters or the methode posted by trioth.

Please escuse my bad knowlegde of this language.
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Old 9th November 2004, 07:27 PM   #9
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Quote:
Originally posted by tiroth
I was just joking
I know.

Quote:
Originally posted by wim
Forget it Carlosfm, you can't measure such low resistances acurate with a standard multimeter (digital or analog) , only with very expensive multimeters, special mili-ohm meters or the methode posted by trioth.
You can.
It's one of the only things that make me sometimes use my old analog multimeter.
Check the link I posted, you can see this feature:

"Resistance measurement: 1 Ohm .. 1 MOhm (4 ranges)"

It just measures to 1MOhm, while my DMM measures to 200MOhm.
But it's in the low end of the scale that analog MM has it's advantages.
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Old 9th November 2004, 08:41 PM   #10
wim is offline wim  Netherlands
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carlosfm, for what i read in the documentation, resistance-measurements are with intern battery from 1,5 DC Volt.

Measuring 0,1 Ohm (thats what the post form Garbage is about) : I = 1,5V/0,1 Ohm = 15A!!! P= 22,5W!!!

The documentation says max. current for measure Ohms is 83 mA.

Or didn't i read the documentation well (possible, becouse i am a Dutch speaking person with only little knowledge of other languages, sorry for that)


Please your opinion??
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