Affordable U67 PSU?

[Greenie]

Is there an affordable U67 PSU for the U67?

 

[Tim Campbell]

All the german techs offer finished power supplies for U67s. Schaal, Drehfal, Voxorama...

 

[RuudNL]

Here is a simple low cost solution that works:
What you need is
- A transformer with two separate 9 volts windings (1 Amp recommended)
- Two bridge rectifiers
- Two capacitors 1000µF/25 V.
- Two of these voltage converters: High Voltage Power Supply Module 250V 6.3V DC Converter NIXIE&Magic Eye Tube HV | eBay

You have to use two separate transformer windings, because you don't want a common (negative) ground.
Use a bridge rectifier and a smoothing capacitor on both transformer windings.
Connect the rectified and smoothed voltage to each input of the voltage converters.
Adjust the output of one voltage converter to 210 Volts.
The negative side of the 210 Volts output is the common 'ground', the positive 210 V output is the + anode voltage.
From the other (6,3 Volts converter), connect the positive output side to the negative output of the 210 V. converter (=ground)
The negative output side of the 6,3 V. converter is now the (negative) 6,3 filament voltage.

I have used this setup in a power supply for a tube microphone and it works great.

 

[Greenie]

Good tip, I will try that.

 

[Greenie]

Here is a simple low cost solution that works:
What you need is
- A transformer with two separate 9 volts windings (1 Amp recommended)
- Two bridge rectifiers
- Two capacitors 1000µF/25 V.
- Two of these voltage converters: h Voltage Power Supply Module 250V 6.3V DC Converter NIXIE&Magic Eye Tube HV | eBaHigy

You have to use two separate transformer windings, because you don't want a common (negative) ground.
Use a bridge rectifier and a smoothing capacitor on both transformer windings.
Connect the rectified and smoothed voltage to each input of the voltage converters.
Adjust the output of one voltage converter to 210 Volts.
The negative side of the 210 Volts output is the common 'ground', the positive 210 V output is the + anode voltage.
From the other (6,3 Volts converter), connect the positive output side to the negative output of the 210 V. converter (=ground)
The negative output side of the 6,3 V. converter is now the (negative) 6,3 filament voltage.

I have used this setup in a power supply for a tube microphone and it works great.

I bought the two voltage converters, any suggestion as to what 9v transformer?

 

[RuudNL]

Any transformer that can deliver (2x) 1 Amp at 9 Volts
Even this transformer would be sufficient (2 x 9 V / 0,83 A)

 

[Khron]

- Two of these voltage converters: High Voltage Power Supply Module 250V 6.3V DC Converter NIXIE&Magic Eye Tube HV | eBay

What chips are those using? 34063 possibly, and..?

 

[capacitor]

Those HV power supply modules look really cost effective! Any reason why a pair of inexpensive pair of 12VDC @ 1A generic power supplies could sub in for the transformer + bridge rectifiers?

Those are a couple bucks each at the local thrift shop. Usually they are SMPS and the DC output ground is isolated from everything.

 

[RuudNL]

What chips are those using? 34063 possibly, and..?

I think I looked this up in the past. The type numbers are very difficult to read.

@Khron: Here is the answer
DON'T USE DC-DC step down/buck switching converter circuits for H+

Usually they are SMPS and the DC output ground is isolated from everything.

On the small PCBs I referred to the output is not isolated. (No transformer.) So if you want a negative filament voltage, needed for a U67, you have to use separate transformer windings.

 

[TLRT]

I some spare fully completed PSU with Dany's U67 board,write me if interested.

 

[RuudNL]

This is my 'poor man's U67 power supply'!
Two "Chinese" DC voltage converters that can deliver 6,3 V and 150-280 V output.
Because the U67 needs a negative filament voltage (the 6,3V and HT on the modules have a common ground), I used a transformer with two separate secundary windings. Each voltage converter has its own rectifier, smoothing capacitor etc. This way I can get -6.3 V and + 210 V. Each voltage converter has a 7809 regulator.
As an extra precaution I have added a 4.7K/47µF filter on the output of the 210 V.
Size is 17 x 10 x 5.5 cm.

 

[mihi_fuchs]

Here's a very affordable solution. Takes up the standard Tbone SCT (https://www.thomann.de/at/the_tbone_psu_sct_2000.htm; 49€). You reuse everything except the PCB. PCB parts are ca. 30 € (mouser.at).
Gives you clean 210V and -6.3V. Works very fine with my clone.



Via the green 2-terminal-block you can either go for common ground or separate the ground for B+ and Heater, in case you want to do that.
I can post schematic and BOM soon, just need to look it up. It's a pretty basic and easy built. If I remember right I even had the calibration line incorporated, but I need to check that up.

Best regards,
Michael

 

[mihi_fuchs]

Here you can find all data:
https://groupdiy.com/threads/u67-psu-from-standard-tube-microphone-psu-for-sct800.87319/

cheers,
Michael