After tedious work and proper testing, I managed to finish today the 600V feedback regulator. Previous version had to be tweaked as LF351 operational amplifier latched up. After a quick PCB hack, the LM358 was replaced instead with instant success. The supply can regulate from 0 to 600V and provide up to 100mA:
Hello Alejandro,
What changes would you do in the power supply circuit, if we have the following requirements:
1- allow the output voltage to increase slowly from 0 to 600V in about 60 seconds (say at a rate of 10V per second), but keeping the retifiers solid state, not using a tube retifier such as GZ34 or equivalent). The idea is to mimic the behaviour of a tube retification, which makes the output voltage to grow slowly;
2- allow the output current going up to 3000mA (3A);
3- over voltage protection (say the raw filtered DC going from 620V to 720V in the middle of the night…) without any side effects to the output;
2- over current protection by lowering the output voltage from 600V slowly (say at a rate of 10V per second) down to zero, when the load current reaches 3001mA. When the load current goes back to normal, i.e. below 3000mA, the output voltage would increase slowly say, by 10V per second until 600V. However, if the load current insists in drawing more than 3000mA for more than 30 seconds, the power supply would switch itself off.
Cheers and congrats for your excelent work!
Giorgio Coniglio
PS: is your valve curve trace for sale? I just loved it!
Ciao Giorgio,
What is the intended use of this supply? If it is for a power amplifier I strongly suggest you not to follow this design, as it doesn’t “sound” good due to the feedback regulation. Better go with a standard passive regulator.
1 – you could achieve this by using a mosfet follower with a capacitor in the gate to slowly bring the voltage up. Also this can have a current protection circuit
2 – Modify R4 which is current limiter. However, you need to look at the pass mosfet as well. What would be the input voltage?
3 – If you use a passive follower with a zener string you could somehow manage to provide stabilisation to the output voltage
4 – 600V @ 3A is a serious supply (1.8kW), not a beginners supply! You can modify this circuit to set the current limiter (Q1 and R4) to cut off at 3A.
Thanks for looking around
PS: I’m afraid but the tracer is not for sale. Took me a long time to build it and so far I’m using it a lot. Is there any particular valve you are after to trace? Unfortunately I don’t have too much time for this hobby, otherwise I could build one for you, etc.
Cheers,
Alejandro
Nice to see it ended up working after all!
i only just recently stumbled upon your website. i totally forgot about the threat on diyaudio.
kind regards V4lve
Thanks, It works like a charm! It has been used and abused and performs flawlessly so far. Thank you again for the help in refining this design
Ale
Hi,Al,
Ilike your construction of your voltage regulator 0-600V/100mA.But 0-400V/100mA is really OK with me,so I have dec resistors R7 for 600kohm,R8 for 7k5 so the regulation can work for 0-400V.But I donˇt know if shall make change resistor R2 and R3,if so what kind of values do you recommended to set on?? The entrance suspense will approximatelly be anout 430V.
Thanks a lot for your help @ tc
Regrds Zdenek Czech republic
mail adres: [email protected]
“What is the intended use of this supply? If it is for a power amplifier I strongly suggest you not to follow this design, as it doesn’t “sound” good due to the feedback regulation. Better go with a standard passive regulator.”
Wait I thought feedback regulators have much lower output impedance and sound better then passives? I am very strongly considering building this power supply with a 600ma limit for general prototyping.
If you read the original thread, this is only intended to test valves.
Feedback regulators doesn’t sound good at all… don’t waste your time. A nice LCLC filter is the only thing you need.
I would like to build one but I have a few questions:
Are all resistors (like R4 and R5) standard 1/8W resistors unless otherwise mentioned?
Does Q1 and M2 also need a heatsink?
Can you post a picture of the finished project and PCB (I’m just curious).
Thanks.
Hi Ralph.
This is an old design so I’m trying to remember things as my notes are not at hand.
R4 and R5 expect very low voltage drop and given their resistance values you should expect low wattage parts. However, because this is a HV design I’d go with 1/2W and 1W on the rest as they have a higher voltage tolerance. Check with the manufacturer and work it out. Ohm’s law is your best friend!
Unfortunately I have no pictures of the board and can’t open it easily for taking one.
Cheers
Ale