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Old 8th May 2009, 07:40 PM   #31
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Default Paulb... this is a very good idea!


Thank you.... i will manage to try a capacitance multiplier using zener diodes. (36V plus 12 volts in series)

regards,

Carlos
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Power supply; ripple, filter, noise, stability and the use of capacitance multiplier... Portuguese and English; https://www.youtube.com/watch?v=sSm0ku1eIgg
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Old 8th May 2009, 08:32 PM   #32
paulb is offline paulb  Canada
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You're welcome Carlos.
For those interested, here's Rod Elliot's version of the capacitance multiplier:
http://sound.westhost.com/project15.htm
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Old 8th May 2009, 10:08 PM   #33
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Default I have tested minutes ago.... i had too much voltage drop


now testing the electronic regulator.... will test tomorrow to see how long it wii accept short circuit into the output,,,,will install more power transistors in paralell and will let the system heat up for a couple of minutes,,,, short from positive to ground and from negative to ground simultaneously.

Why that monster behavior?

Safety!.... amplifier can burn,....,shorts can happens into power amplifier board (this happens sometimes when hard used, bad cooled or too much low speaker impedance),.... fuses can fail to open the circuit.... then overload can short the series pass transistors into the electronic supply....this happening will send 80 volts to the amplifier circuit..... well.... i want to avoid this mess beeing sure the regulator will survive, even shorted for a couple of minutes.

The electronic stabilizer circuit (output voltage adjustable) will keep the voltage pre adjusted within 10 percent.... also allow you to adjust perfectly... so you can adjust 50123 milivolts to the positive and 50123 milivolts negative if you decide to to this way... when transformers never has, absolutelly, the same voltage.

Carlos

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Old 9th May 2009, 01:02 PM   #34
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Default I have tested a modified electronic supply...more transistors into the output


And i had positive regulation...ahahahahah!...very good that..when you enter the load the voltage increases in the place to decrease.

Difference of voltage, under load (regulation) from positive rail to negative rail is less than 1 volt when you adjust to 50 volts the output..when 2.27A each rail load enters, then the voltage increases to 52 volts in the place to decrease.

I have also made tests using lower voltage..around 35 volts..and current was 5 amperes each rail.... also i could have positive regulation.

Well... camera battery is charging..soon i will upload to youtube and then will post a link here.... so you will be able to see.

The supply was tested 20 seconds with a short circuit.... to see if it will burn output transistors... was fine.

Also heat is fine because input voltage descends...drops under load..so..power over the series pass transistors are not so high.

The current under short circuit i could not measure.... maybe i can, using low ohm resistance (shuntO. and measuring voltage...but for sure is very high...hummmm...maybe 50 amperes under short...or more than that... voltage zero and very high current because of short.

Well..movie will show you.

regards,

Carlos
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Old 9th May 2009, 02:09 PM   #35
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Default First video uploaded to youtube about transformer and supply

http://www.youtube.com/watch?v=ocVA90cPUhE


soon you gonna have the link to the other one, where the voltage was adjusted to 50 volts.

The supply works fine till we reach 55 volts..then the voltage starts to drop and regulation goes bad... at 60 volts the voltage drop goes to 15 percent.

regards,

Carlos
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Old 9th May 2009, 02:11 PM   #36
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Default First video uploaded to youtube about transformer and supply

http://www.youtube.com/watch?v=ocVA90cPUhE


soon you gonna have the link to the other one, where the voltage was adjusted to 50 volts.

The supply works fine till we reach 55 volts..then the voltage starts to drop and regulation goes bad... at 60 volts the loss goes to 15 percent.

regards,

Carlos
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Old 9th May 2009, 02:50 PM   #37
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Default The second one

http://www.youtube.com/watch?v=PW7jfHCuIbI

regards

Carlos
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Old 9th May 2009, 05:02 PM   #38
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Default What i have to tell you folks


I have made testings:

My first assumption was thinking the vbe multiplier capacitance existent into my circuit could could filter without using big condensers (big capacitance values) into the supply...i was wrong...we need that capacitance..no way... when sucking amperes the noises appear..the filtering into the electronic power supply helped a lot...but could not fix.

My second assumption is that i would not need too much speed to correct voltage errors.... the error amplifier could work without problems because was a reasonable transistor... wrong once again!... speed was a problem.. i have perceived into the sound reproduction... the attack was strange...had a delayed decay but had a decay.

This approach, this supply, this idea, will not fit even a class A amplifier where you have not too much current variation..say..starts high and continues beeing high... comparing maximum power current into class A amplifier to the stand by current results in smaller number compared to the division of maximum current by the stand by current into class AB amplifiers.

This one, with electronic regulator, at least this one, cannot be used with class A amplifiers too because of filter size...the idea was to use small filter after rectification..but this do not works...the electronic supply cannot make the miracle i was wishing.

This is what happened folks..i will continue with my buzzer transformer playing good sound till i have better transformer to replace.

regards,

Carlos
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Old 9th May 2009, 05:23 PM   #39
Bigun is offline Bigun  Canada
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Can you include a notch filter to the amplifier front end, maybe too complicated and bad for sonics ?
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