Power Supply Tube Preamplifier.

[Pim Driessen]

Dear Forum Members,
I have a question about a current limitation in a power supply for a Tube preamplifier output 215 Volt.
The question is Does this work if you accidentally create a short circuit?.
Here is the diagram of 2 different power supplies, the first one broke due to a measurement error, of which it is not entirely clear what went wrong.
The second diagram is of a tube preamplifier from Audio and Technology from a long time ago, I personally think the current limitation of Audio and Technology looks better.
When I simulate in Tina Software, the current limitations of both seem to work, but as I wrote before, the power supply board of the first diagram broke after a short circuit.
What is the opinion of this Forum about the two power supply diagrams?.
Greetings,
Pim

 

[crutschow]

I didn't realize that the entire circuit as described by you, has to be built in, that will be an extra printed circuit board.

No.
The entire circuit was to demonstrate its operation with a regulator.

Only the two transistors below with their associated parts need to be added to your circuit, connected as I stated in post #18:

Yes, the BF459 should work for both those transistors.

 

[Pim Driessen]

Ok, that makes it a lot easier.
Now I suddenly realize that it might be useful if I try this out with the power supplies that were previously in the tube preamp, the prints from the photo that was added earlier.
Here is the diagram schematic again.
And then I think that transistor T4 can be removed, that is the current limitation, or can it remain in place?

 

[crutschow]

then I think that transistor T4 can be removed, that is the current limitation, or can it remain in place?

No, leave it in.
It limits the current for the short delay until the electronic fuse circuit shuts it down.
Good to have both.

 

[Pim Driessen]

Too bad it doesn't work, all values change, but nothing happens, here is the picture.

 

[crutschow]

Too bad it doesn't work, all values change, but nothing happens, here is the picture.

What do you mean, "all values change, but nothing happens"?
What do the voltages do at T4's collector, and U1's gate?

C1 should be 10nF, R4 should be 1meg, and R5 510k.
Those low resistor values will zap the transistor.
Why did you use different values?

 

[Pim Driessen]

The reason I started using different values was because nothing happened, I started with the values you provided.
If the switch SW-SPST3 is pulled, reset,
the power supply will start properly.

 

[crutschow]

Try increasing the value of C1.

 

[Pim Driessen]

I raised it but that didn't work any better.
But then I saw that there was a connection between 2 zeners that was loose, it seems to work fine now,her 2 pictures

 

[crutschow]

it seems to work fine now,her 2 pictures

It may work as shown but I see an an error in the fuse connection.
The collector of Q5 should be connected to the base of T2, not T1.
The connection to T1 means T5 has to sink an excessive amount of current to shut down the regulator and likely will zap T5.

 

[Pim Driessen]

That is solved, and it works, but I have to reset the previously mentioned switch, should C1 be a bipolar capacitor?.
Can the electronic fuse also be tested in a 22 volt power supply, because I would rather not do that with the 215 Volt power supply, diagram of the 22 Volt power supply is coming.

 

[Pim Driessen]

This is the schematic of the power supply, the voltage coming out of the PCB is slightly lower, 22 volts.

 

[Pim Driessen]

I measured the power supply board, but it is only 18 Volts.

 

[Pim Driessen]

19 volts comes out of the power supply

 

[Pim Driessen]

This is the original schematic of the 19 volt power supply.

 

[Nigel Goodwin]

Is this a competition for who can design the most complicated power supply?.

 

[Pim Driessen]

Hi Nigel, No that is definitely not the case, the last diagram schematics are existing designs, and not designed by me.

 

[Nigel Goodwin]

Why a regulated supply in a valve preamp anyway?.

 

[schmitt trigger]

Pim; A suggestion;
to be able to follow up a signal path on a schematic, the custom is for the inputs to be on the left, the output on the right.

 

[Pim Driessen]

Why a regulated supply in a valve preamp anyway?.

Out of curiosity, that would sound even better, but now that I have a power supply of electrolytic capacitors and resistors I am not dissatisfied with how it sounds, but would still like to know if there is a difference in the sound.

 

[Pim Driessen]

Pim; A suggestion;
to be able to follow up a signal path on a schematic, the custom is for the inputs to be on the left, the output on the right.

The last diagram schemes are from a long time ago, I usually do it from left to right these days, but thanks for the tip.