12 volt tube mixer

[iampoor1]

https://desmith.net/NMdS/Electronics/NixiePSU.html

I have a couple of these Pcs on the bench, just waiting to be popukated....much better than the cheapie Chinese jobbies from what I can tell. And it's been built by hundreds of people....

 

[ruffrecords]

Unfortunately, according to RS, they are a discontinued product which is a great pity. I have one of the higher power version which I have yet to test. I have also sent a direct enquiry to Meanwell about a 250V 400mA custom supply.

Cheers

Ian

I contacted Meanwell about a 250V 400mA SMPS. The mentioned the LED types and said if I wanted a normal 250V 400mA supply it would need to e a custom one. I thought the LOQ would be very high but they said 100 off would be enough. So I wondered whether there would be enough interest in a group buy?

Cheers

Ian

 

[abbey road d enfer]

There seem to be a few off the shelf 12V to 48V dc/dc convertors but very few 12V to 250V.

You don't necessarily need a "modern" SMPS. In 1975, I designed a portable ENG mixer that incorporated a full POTS telephone. The system needed a 80V 50Hz ring tone (in a 600 ohm line, that's about 10W of power).
I used a very basic astable multivibrator driving two Darlingtons connected to a  12V center-tapped secondary. The two 115V primaries were in parallels. You could probably operate at a higher frequency for core reduction. It is not as efficient as a "real" SMPS, but close enough.

 

[ruffrecords]

You don't necessarily need a "modern" SMPS. In 1975, I designed a portable ENG mixer that incorporated a full POTS telephone. The system needed a 80V 50Hz ring tone (in a 600 ohm line, that's about 10W of power).
I used a very basic astable multivibrator driving two Darlingtons connected to a  12V center-tapped secondary. The two 115V primaries were in parallels. You could probably operate at a higher frequency for core reduction. It is not as efficient as a "real" SMPS, but close enough.

I agree; designing one is in principal not too difficult - not too far from a 100KHz bias oscillator with a rectified output. But meeting current EMI legislation is another matter.

Cheers

Ian

 

[abbey road d enfer]

I agree; designing one is in principal not too difficult - not too far from a 100KHz bias oscillator with a rectified output. But meeting current EMI legislation is another matter.

Cheers

Ian

There's no EMI issue if you run it at 400Hz. An ordinary mains xfmr is usable and run at very low flux. You just need to make sure your circuits are well enough shielded.

 

[JohnRoberts]

There's no EMI issue if you run it at 400Hz. An ordinary mains xfmr is usable and run at very low flux. You just need to make sure your circuits are well enough shielded.

A 400Hz square wave can still have significant HF energy.

JR

 

[abbey road d enfer]

A 400Hz square wave can still have significant HF energy.

JR

The current in the primary is not really square, and harmonics are easy to filter out. The output voltage is a very distorted sinewave. Indeed it takes some attention.

 

[ruffrecords]

Some interesting designs here:

http://royalsignals.org.uk/photos/inverter.htm

Cheers

Ian

 

[abbey road d enfer]

Some interesting designs here:

http://royalsignals.org.uk/photos/inverter.htm

Cheers

Ian

The first schemo is almost exactly what I did 40+ years ago.

 

[Tubetec]

I did ask about using 400hz with regular transformers , so we could certainly improve magnetic radiation from the core by doing this, if its a square wave it will have loads of harmonics ,but we should be able to filter this hash well . I did mention in relation to  VFD motor invertors and if that would present any possibilities , I not exactly sure what a variable frequency drives put out ,I would imagine its something approximating a sine ,maybe someone knows more ?