HI @ all,
i need a regulated power supply for my
60V preamp.
actually there is a zener / bd 179 regulation,
but its very unstable and noisy.
the dc input is about 85 Volts. Because of this high
input voltage i can´t use the normal LM317HV type´s
or is there a simple modification. ?
the preamp / channel switch / dc protection
consumes only between 50 mA to 250 mA on the 60 V line...
Best regards
EC
i need a regulated power supply for my
60V preamp.
actually there is a zener / bd 179 regulation,
but its very unstable and noisy.
the dc input is about 85 Volts. Because of this high
input voltage i can´t use the normal LM317HV type´s
or is there a simple modification. ?
the preamp / channel switch / dc protection
consumes only between 50 mA to 250 mA on the 60 V line...
Best regards
EC
hi.
This is an circuit of mine from november 2006.
U2 is a VBE multiplier with a voltage at BASE of 30 Volt.
R3 adds the 90 Volt to 120 Volt output.
U2 Base voltage is set by TL431 ( max 36 volt adjustable zener, temp stable ),
via divider R2/R1.
U3 is a Constant Current Source, 1 mA,
through TL431 and the 2N5551 (U2) .. for constant performance.
R5 should be chosen to provide enough current:
- A couple of mA for U3
- 1 mA for TL431
- Base current for U4 = MJE340 .. THE OUTPUT TRANSISTOR.
I have used 4 mA
C1 is for stability. May be adjusted in value.
You might have to add some compensation cap somewhere for increased stability, even if my simulation did not show anything but good and precise operation into various constant DC current loads.
It is a bit different when you have an AC Current load.
A Common STAR Ground is used for best zero reference.
R3 should be used for adjusting output voltage.
It is approximately 1 kohm per Volt.
I have used 2N5551, MJE350 & MJE340
because they are High Voltage transistors from Motorola.
Lineup
---------------------------
This 120 Volt regulator was created for my exploration of very high voltage Class A preamplifiers.
With use of very low global feedback factors.
This is an circuit of mine from november 2006.
U2 is a VBE multiplier with a voltage at BASE of 30 Volt.
R3 adds the 90 Volt to 120 Volt output.
U2 Base voltage is set by TL431 ( max 36 volt adjustable zener, temp stable ),
via divider R2/R1.
U3 is a Constant Current Source, 1 mA,
through TL431 and the 2N5551 (U2) .. for constant performance.
R5 should be chosen to provide enough current:
- A couple of mA for U3
- 1 mA for TL431
- Base current for U4 = MJE340 .. THE OUTPUT TRANSISTOR.
I have used 4 mA
C1 is for stability. May be adjusted in value.
You might have to add some compensation cap somewhere for increased stability, even if my simulation did not show anything but good and precise operation into various constant DC current loads.
It is a bit different when you have an AC Current load.
A Common STAR Ground is used for best zero reference.
R3 should be used for adjusting output voltage.
It is approximately 1 kohm per Volt.
I have used 2N5551, MJE350 & MJE340
because they are High Voltage transistors from Motorola.
Lineup
---------------------------
This 120 Volt regulator was created for my exploration of very high voltage Class A preamplifiers.
With use of very low global feedback factors.
Attachments
Hi EC,
you should read datasheets more carefully
First paragraph LM117/317 datasheet
You can even regulate the heater of tubes at several hundred volts if you want - as long as the differential input-output is below 37V.
And that applies already to the 'low voltage' LM317 - you don't even need the high voltage variant you refered to.
Have fun, Hannes
you should read datasheets more carefully
First paragraph LM117/317 datasheet
You can even regulate the heater of tubes at several hundred volts if you want - as long as the differential input-output is below 37V.
And that applies already to the 'low voltage' LM317 - you don't even need the high voltage variant you refered to.
Have fun, Hannes
I don't agree about the low power dissipation at start up.
I think the 317 will go into current limit trying charge up the output capacitor with near full input voltage across the 317.
If the chip is cold and is trying to pass 1.5Apk AND has 60V across it then I can't see how this stays inside the operating spec. of the reg.
I think the 317 will go into current limit trying charge up the output capacitor with near full input voltage across the 317.
If the chip is cold and is trying to pass 1.5Apk AND has 60V across it then I can't see how this stays inside the operating spec. of the reg.
Look up threads on the MAIDA regulator -- very simple to implement, quiet.
In addition to the TL783 you can use the LR8N3 -- the latter device was designed for supervisory voltages in switch mode regulators but can also be used for high voltages. It's about $0.68 at Mouser. For more current you can use it with an external pass transistor like the MJE3439...
In addition to the TL783 you can use the LR8N3 -- the latter device was designed for supervisory voltages in switch mode regulators but can also be used for high voltages. It's about $0.68 at Mouser. For more current you can use it with an external pass transistor like the MJE3439...
Andrew, you're a reliable fellow
After typing the last post in a hurry, I already thought you would object - and you're right.
<Edit: I thought of suggesting a voltage clamp to limit differential voltage, but thinking of it it's maybe not a good idea as the components after the regulator would see the high voltage as well>
Concerning power dissipation: a quick estimate gives me 40ms charging time for a single 1000uF output cap, assuming the current to be constant and at current limit (1.5A). The power dissipation per second would be 45 W then, which the part should survive since this number only lasts for the 40 ms charging time.
However by taking another look at the datasheet it's clear that my quick and dirty calculation even overestimates the power dissipation as the current limit is not 1.5A, but only 0.4A for more than 40V voltage difference.
I agree, it's easiest just to take a higher voltage regulator.
Have fun, Hannes
After typing the last post in a hurry, I already thought you would object - and you're right.
<Edit: I thought of suggesting a voltage clamp to limit differential voltage, but thinking of it it's maybe not a good idea as the components after the regulator would see the high voltage as well>
Concerning power dissipation: a quick estimate gives me 40ms charging time for a single 1000uF output cap, assuming the current to be constant and at current limit (1.5A). The power dissipation per second would be 45 W then, which the part should survive since this number only lasts for the 40 ms charging time.
However by taking another look at the datasheet it's clear that my quick and dirty calculation even overestimates the power dissipation as the current limit is not 1.5A, but only 0.4A for more than 40V voltage difference.
I agree, it's easiest just to take a higher voltage regulator.
Have fun, Hannes
Perhaps a bit on the edge of its capabilities but another option to consider is the Linear Technology LT3012
http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1040,C1055,P13772
http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1040,C1055,P13772
Please excuse me Sir if I take again this very interesting 3D
First of all a precisation
I went today to RS to buy some TL783 to build a 60V regulated PS (I started another 3D on this)
As the 783s were not available but they must be ordered to make a long story short I went out with some LM317TG
I understand from this 3D that the 317, with some precautions, can be used to regulate high voltages (I need a Vout=60V)
If I also understand well the main precaution is to place a 36V zener across its in and out pin ? (I hope to orientate it correctly)
As you may be understand I am very beginner.
A friend of mine gave to me a bride of zen preamp but without the PS.
Thank you very much again and kind regards,
ginetto
Last question
What about the protection diodes usually used with the lm317 like here
http://www.elecfree.com/electronic/...power-supply-regulator-15v3v45v5v6v9v_15a.jpg
Which IN4001 will the 36V zener replace ?
Sorry to ask all of these question but I have already burnt half a dozen 317
One even collapsed on itself with a loud sound
Thanks and regards,
ginetto
What about the protection diodes usually used with the lm317 like here
http://www.elecfree.com/electronic/...power-supply-regulator-15v3v45v5v6v9v_15a.jpg
Which IN4001 will the 36V zener replace ?
Sorry to ask all of these question but I have already burnt half a dozen 317
One even collapsed on itself with a loud sound
Thanks and regards,
ginetto
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