simple MOSFET source folower suggest me please - diyAudio
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Old 24th July 2003, 06:31 AM   #1
aiwonsi is offline aiwonsi  Thailand
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Default simple MOSFET source folower suggest me please

I found this schem in internet
http://home.zonnet.nl/tschrama/owndesign.html

can anybody suggest ?

how can I build power supply?

or more

I'm a newbie

some parameter

generator: 1K Ohm amperes: 2.618 Amp
device: IRF530S power@1%2/3rd: 7.558 Watt
z-Bias: 100K Ohm dissipation: 86.39 Watt
Bias Voltage: 25.2 Volt rendement: 8.749 %
z-source: 8 Ohm gain: 0.908 x
output capacitor: 4700uF Z-out: 0.2588 Ohm
supply: 33 Volt -dB @ 10 Hz: -0.6614 dB
z-speaker: 8 Ohm -dB @ 100 kHz: -0.0323 dB
rimple rejection: 0.648 %

THD@0.33Watt THD@1Watt THD@3Watt
0.125 % 2nd 0.223 % 2nd 0.432 % 2nd
0.006 % 3rd 0.022 % 3rd 0.079 % 3rd
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Old 24th July 2003, 05:48 PM   #2
PMA is offline PMA  Europe
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Don't you want to try this one, you'll get better linearity and other parameters.
http://www.pha.inecnet.cz/macura/follower_e.html
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Old 25th July 2003, 07:43 AM   #3
aiwonsi is offline aiwonsi  Thailand
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thank you

but can I use low voltage for low power?

thank again

aiwonsi
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Old 25th July 2003, 08:10 AM   #4
Fuling is offline Fuling  Sweden
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Go find (or wind) yourself a pair of big chokes.
YouŽll double the efficiency compared to a CCS design.
Something like 100mH is enough for 8 ohms load.
There are some threads in this forum about choke loaded solid state amps, have a look.
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Old 25th July 2003, 08:30 AM   #5
Nicwix is offline Nicwix  Australia
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I prefer this one ... the PSU is less critical. Obviously the PSU voltage and the CCS current can be scaled.

Nicwix
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Old 25th July 2003, 08:52 AM   #6
PMA is offline PMA  Europe
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Hi aiwonsi,

yes, you can use lower voltage for lower power. In that case you have to maintain at Gate of T1 voltage Vs/2 + 4V. That means that for supply voltage of 24V you need 16V at gate of T1. This can be done by changing of R3 value. The circuit as shown (mosfet power follower) is not much sensitive to supply voltage ripple. The supply ripple rejection is about 60 dB, standard bridge and cap supply can be used. You will find one on my web page, same address as shown above. Fig.5. In case of more questions you can send me an e-mail.

Pavel
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Old 25th July 2003, 10:59 AM   #7
aiwonsi is offline aiwonsi  Thailand
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thank everybody,

I'm a newbie.
I'm very fool about electronic.
I have some question.

I wan't about 5watt load 8 ohms. How do I change this circuit(power follower)? And why?

aiwonsi
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Old 25th July 2003, 11:15 AM   #8
PMA is offline PMA  Europe
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For 5W/8 Ohm you need output voltage of 6.5Vrms.
P = 6.5 x 6.5/8 = 5.28 W
For 6.5Vrms you need supply voltage at least 20V.
Vs = 2 x 1.414 x 6.5 = 18.38 + saturation voltage of transistors.
For single ended class A you will need Iq (quiescent current) at least 1.2 A for 5W/8 Ohm.
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Old 25th July 2003, 12:34 PM   #9
Luke is offline Luke  New Zealand
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Default mj amp

Quote:
I found this schem in internet
http://home.zonnet.nl/tschrama/owndesign.html

has anyone built the mj amp at the bottom of this page?
Curious about it.
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Old 25th July 2003, 12:46 PM   #10
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Default Re: mj amp

Quote:
Originally posted by Luke



has anyone built the mj amp at the bottom of this page?
Curious about it.

this is one of those Mosquito/Zenquito designs that originally used JFETs upfront and Mosfets in the ops. In my simulation, it worked well, except that it has large cross-over distortion that i couldn't get rid of.

It originally attracted for its simplicity. and I would like to see other's experience with it as well.
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