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Old 11th December 2011, 09:44 PM   #11
kees52 is offline kees52  Netherlands
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Quote:
Originally Posted by Sch3mat1c View Post
Than bipolar junction transistors I assume you mean?

This is incorrect because BJTs have higher transconductance than MOSFETs do, at comparable operating conditions.

This doesn't matter much, because the circuit shows a big fat 22uF crushing the loop response. The output impedance of this regulator will be approximately 1/Gm of Q1, which will be in the 10s of ohms range most likely.

If R4 and C4 were removed and a small compensation capacitor (or R+C) placed across R2, and the values adjusted until critically damped transient response is obtained, you will have the lowest possible output impedance and highest PSRR. I would guess Zo will be in the miliohms, especially with BJTs, while PSRR will be >40dB.

Further improvement can be made by reducing the bias current supplied from R3; 100k or even 1M will suffice here, at some expense to high frequency response (which is easily compensated for with a customary filter capacitor on the output). This also relaxes the operating point for BJTs, which are often 2nd breakdown limited at these voltages and higher.

As a final step, the error amplifier can be changed from a single transistor to a differential pair, at the expense of one small transistor; this will essentially transform the tempco from an obvious Vbe error down to the error of D1, which could also be replaced by a lower voltage zener (with predictable tempco), or a bandgap reference such as TL431.

Then you'll have essentially the regulator circuit I built here, with a bit higher current capacity:
Click the image to open in full size.
For that matter, this circuit will do an excellent job under the same conditions, replacing the pass transistor with a MOSFET and adjusting the current shunt resistor accordingly.

Tim
Looks nice but I need only low current q50 mA max, but I will try your for a test, I have also need a negatieve one because the white follower has differential supply, there is much on the internet about regulators, it seems complicated or maybe whe are never satisfy ;-).

I dont need a mosfet pass transistor persee, a bjt will do, oly I have a lot of high voltage mosfets here so I try first.

This moment the amps works with two gyrators in the supply, the ripple in the loudspeakers are now gone, it is deep black.

thanks all.
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Old 12th December 2011, 03:22 PM   #12
kees52 is offline kees52  Netherlands
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I have now do 2 things, one is a normally lm317 floating and protected with a fuse and transient diode of some amps, it works in simulation en is simple, with 80 db riple rejection .

or the one from post 11 I have done with a mosfet, I think that a normally LM317 is for me just fine and simple, maybe remove the transient diode and use a darlington npn for input as a current limiter, can simple with a zener. even a thyristor acros the lm317 can work together with a fuse.
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Old 12th December 2011, 08:27 PM   #13
Elvee is offline Elvee  Belgium
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These regulators are nominally a bit more complex, as they use three transistors, but they remain inexpensive and have decent performances considering their cost/complexity:
Simple HV series regulators

Another route is to use complementary transistors.
This example is based on a P channel ballast, but if there are no grounding issues, polarities could be swapped (bypassing could be added to improve AC performance):
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Old 12th December 2011, 08:30 PM   #14
kees52 is offline kees52  Netherlands
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Well these I going to use, I go make a pcb for them. it will a supply contents of plus minus 110 volt, and one 300 volt for the hybride amplifier.

I have test the one with lm317 and have try to kill it but it is quite good, it is very good protected, I have afcourse relative low voltage this counts also, I here here about 600 volt and more, there are transient diodes who can protect mosfets and transistors when power up and cause trouble with electrolitic capacitor who has to be charged, and thus see a short for a short time, here these diodes can help?

Transient Voltage Suppression, TVS Diodes, Automotive Circuit Protection - Littelfuse.com
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Old 12th December 2011, 08:35 PM   #15
kees52 is offline kees52  Netherlands
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Originally Posted by kees52 View Post
Well these I going to use, I go make a pcb for them. it will a supply contents of plus minus 110 volt, and one 300 volt for the hybride amplifier.

I have test the one with lm317 and have try to kill it but it is quite good, it is very good protected, I have afcourse relative low voltage this counts also, I here here about 600 volt and more, there are transient diodes who can protect mosfets and transistors when power up and cause trouble with electrolitic capacitor who has to be charged, and thus see a short for a short time, here these diodes can help?

Transient Voltage Suppression, TVS Diodes, Automotive Circuit Protection - Littelfuse.com
the transistors in differential has to be 3906 and not 5401 but did simulate with them, diff works on low voltage so 3906 are oke, I hope I did alright with the negative one swapping everything and also transistors for pnp to stay on same working of schematic (vbe).
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Old 12th December 2011, 11:11 PM   #16
kees52 is offline kees52  Netherlands
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I have make the schematic ready for pcb making, it is one 2x 110 volt diff supply max 150 mA and one 300 volt gyrator one with max 50 mA.

I have choosen for gyrator in this small amp supply it is not critic there with the mu follower and it's ripple is low.
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Old 13th December 2011, 08:34 PM   #17
kees52 is offline kees52  Netherlands
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I have play with ultiboard in multisim but ohhhh wat much bad components who have complete differend shapes, also the pad,s are mucho to small
and it is a lot of work to make them proper dimensions.

I go asap to eagle, or better Designspark pcb who is I think eagle.

some here experience with ultiboard? I have the dos version here, but dos is no more but that version of ultiboard was very good and easy.
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Old 4th September 2013, 09:03 PM   #18
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you have the layout of a voltage regulator to download a symmetric voltage +180 0 -180 to +80 0 -80 Vdc?
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