PSUs for tubes

Hi,
some notes to this converter.

Its connections and regulators are not documented at the pages nor on the PCB silkscreen. I added some description. Note that the anode voltage Ua is not directly grounded and must not be! There is a current sensing resistor about 3 ohms between -Ua and GND. The resistor can be bypassed by an external capacitor if necessary.

It should be possible to change (lower) the range of Ua by tweaking the resistors at the output. Very small sized SMD resistors are used and they are stuck between a big 450V capacitor and screw connectors, so changing them would be quite a challenge.

The variable resistors should be replaced by potentiometers in a laboratory PSU.

BR from Ivan

Hi Harry, wrote:I like the text "... pls put insurance below the transformer replaced the 0-ohm resistor". I resume they mean replace the fuse for a 6" nail to get more current.

Yes, "insurance" probably means "fuse". Machine translations often yield funny results.

I am thinking about putting a 12V DC PSU into a box together with one regulated buck inverter for heater, a boost one regulated around 200-350V and another regulated around 90-170V for anodes (net and battery tubes). A panel voltmeter and a connector for external 12V source (car battery) would make the laboratory device complete.

Thinking about boxes, please keep your fingers and all bones in safety.

VBR from Ivan

Hi Ivan,
Thank you for the links. They look really interesting.

This 5V to 1200 volt board seems to remind me of the electronics in those 1980s flourescent lamps for caravans.
Really simple circuit, oscillator driving a power FET and pulse transformer. Those in the caravan lamps had a self-ocillating power transistor with feedback from the transformer. I really love this thing in it's simplicity.

I like the text "... pls put insurance below the transformer replaced the 0-ohm resistor". I resume they mean replace the fuse for a 6" nail to get more current.

In the 1970s I worked for PYE in Cambridge. They got some public interest with a washing machine sold in the staff shop. The manual read "If the fuse repeatedly blows then replace it with a larger value fuse."  We had lots of laughs about that.

Thank you very much for the info. I will be ordering the PSUs on the first post, now that we have finished with Spain. We arrived back last week. The removals var arrived with only a driver, so I have stiff muscles from emptying a removals lorry. But now we have more boxes to unpack.

BR Harry

Hi,
two more boost converters, which may attract some interest. They do not have a heater section.

12V to 45-390V, can probably replace an anode battery

5V or 12V to 300-1200V with voltage multiplier may be suitable for a small CRT

VBR from Ivan

Hi Harry,
the claimed failure rate is funny. I hope they mean 1 device of 10.000 fails...
I have one 30W and one 60W device and I ordered some more 60W ones to make a reserve. The delivery is quite fast. I still did not test them under load though.

I found another PSU for battery tubes. It runs from 12V DC and claimed outputs are:
150 - 420 V DC 60 mA adjustable and
1,2   - 12 V DC 3 A adjustable.
Maybe the anode section can be shifted somewhere to 75 - 210V ?

Transformers and chokes for tubes are quite rare nowadays. Their windings have many many many turns of terribly thin wires so making them withou having a good winding machine is really bad.

Be successfull with your housing problems!
VBR from Ivan

Hi all tube lovers,
you may like these ready-made switching PSUs:
30W  here,
60W  here.
I want to test the stronger version soon. A drawback is that they are not the "proper" ones with a big 50 (60) Hz transformer and a wirewound choke, which are quite rare and expensive now. But they seem to work.

VBR from Ivan