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Old 1st April 2009, 04:54 AM   #1
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Default Rod Elliott's capacitance multiplier supply

http://sound.westhost.com/project15.htm

Quote:
Increasing the capacitance (especially at the input) is recommended, and I would suggest 10,000uF as the ideal instead of the 4700uF shown. This will reduce hum even further, and provide greater stability against short term mains voltage changes. Increased output capacitance will help when powering Class-AB amplifiers, to account for their sudden current demands. I do not recommend more than 4,700uF, as the charging current will be very high.
What number does he mean at the bottom? First he says to use 10mF, then he says not to use more than 0.47mF.
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Old 1st April 2009, 05:48 AM   #2
sumit is offline sumit  India
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Hi

He is saying use min 10,000uF before the transistors and not to use more than 4700uF after the transistors.

If u use more than 4700uF after the trans. it would draw too much current during start up and may blow the serise transistor, which actually reduces the ripple.

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Old 13th April 2009, 01:18 AM   #3
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Default Rod Elliot's Capacitance multiplier

Good day Sir,

I actually used 10,000uF after the transistors but it didn't fry the TO218 transistors that I suspect counterfeits from China (TIP2955/TIP3055), I also implement capacitance multiplier ps in all my SS/chip amp projects, as it surpass the benefits versus the costs. If I needed regulated ps, i connected it after the capacitance multiplier. The diffrence between the linear can clearly be observed.

Regards,

Efren
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Old 13th April 2009, 01:33 AM   #4
john65b is offline john65b  United States
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Hello all,

Would a TIP33C/TIP34C (100V 10A) instead of a TIP2955/TIP3055 (100V 15A) work for a Capacitance Multiplier transistor???
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Old 13th April 2009, 03:50 AM   #5
sumit is offline sumit  India
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" I actually used 10,000uF after the transistors but it didn't fry the TO218 transistors that I suspect counterfeits from China (TIP2955/TIP3055) " Using any semiconductor device near its maximum rating is not adviceable and would result in reduction of life of the device. The transistor may not blow as the surge current capability of the device is high, but still, charging a fully discharged 10000uF capacitor causes the device to over conduct its limit, and would cause life reduction. A lot of times what saves the transistor is the impedance of the transformer which limits the output current.

" Would a TIP33C/TIP34C (100V 10A) instead of a TIP2955/TIP3055 (100V 15A) work for a Capacitance Multiplier transistor " Its all about safety margin. If upto 4 to 5 amp contineous is required TIP33/34 can be used.

rgds
Sumit
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Old 27th April 2009, 05:18 AM   #6
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The amp(s) I'd like to use this supply for will probably need to output a peak current of about 25 A. Will I be OK with the number of caps shown, or do I need to parallel?

The input caps and input filter caps that I would like to use are rated at 4.4 A and 2.3 A ripple current, respectively.
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Old 27th April 2009, 06:28 AM   #7
sumit is offline sumit  India
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25amps peak :- which transistors r u using?

This supply is ment for class A operation not for AB or B type amps. What kind of amp u r planning?

You probably need to parallel caps but u need a transiator hefty enough to handle the in rush current. May be u need to parallel transistors too.......
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Old 27th April 2009, 07:25 AM   #8
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A 10-channel LM3886-based amp. I don't know which transistors I will be needing yet.
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Old 27th April 2009, 08:29 AM   #9
AndrewT is offline AndrewT  Scotland
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Quote:
Originally posted by 454Casull
A 10-channel LM3886-based amp. I don't know which transistors I will be needing yet.
two channels of lm3886 running on +-35Vdc into 8ohm speaker can demand transients approaching 22Apk.

What will 10 channels demand?
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Old 27th April 2009, 08:35 AM   #10
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Quote:
Originally posted by AndrewT
two channels of lm3886 running on +-35Vdc into 8ohm speaker can demand transients approaching 22Apk.

What will 10 channels demand?
I only want 330W peak out of it. Adding up all the calculated currents per channel, I'm at about 20 A, with a few more for good measure.

The (slightly old, but about the same) calculations I'm using can be found here:

http://www.audiocircle.com/circles/i...2618#msg622618
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