Using Battery for 300v B+ ?

[mark02131]

How do I get 300v for the B+ from a battery ? I know the first radio's were powered by battery but not sure how they stepped it up.

Thanks
Mark

[Pyre]

They used vibrator circuits and batteries connected in series.

[Pyre]

Sorry link did not come through

link

[mark02131]

Thanks,
That's pretty ingenuous. Definitely not something we would use today to run our amp's "off the grid" though.

[revintage]

Nowadays you use switched DC/DC-converters instead . I use 5W 12-210V Recom modules to power my preamps.

[Mickeystan]

Mark,

In the very early days of radio, there were "B" batteries made for the purpose of supplying B+ to the high tension circuits. These batteries were made by series many smaller voltage cells inside a single "B" battery package. Tube type car radios produced their B+ by using electromagnetic vibrators to switch the 12V dc on and off alternately to the primary side of a transformer. The stepped up secondary side of the transformer was then rectified and filtered to a smoothed DC at the high voltage level. If you are wanting to make high voltage DC today from a lower level DC battery voltage (e.g. 12V dc to 300 vdc), a boost dc inverter topology power supply is likely the best approach. A number of manufactures make IC specific for this purpose.

DMSpike

[JoshK]

Does anyone know what the waveform was like for these vibrator circuits?

I have two huge APS battery packs that have 4 12v/7ah batteries in them to produce 54Vdc output. They have built in autochargers and all. Of course I could just put them in series to create 108v B+ but this is worth looking into for a preamp or phono amp.

[mark02131]

Originally posted by Mickeystan
Mark,

If you are wanting to make high voltage DC today from a lower level DC battery voltage (e.g. 12V dc to 300 vdc), a boost dc inverter topology power supply is likely the best approach. A number of manufactures make IC specific for this purpose.

DMSpike

I was wanting to generate a very clean 300 B+ from 12v I will look at using an inverter. They look fairly simple to implement.

Mark

[Bandersnatch]

hey-Hey!!!,
Get an HEV pack. Ford Escape or Toy Prius have similar voltage and capacity.
cheers,
Douglas

[richwalters]

Originally posted by mark02131
How do I get 300v for the B+ from a battery ? I know the first radio's were powered by battery but not sure how they stepped it up.

Thanks
Mark

The B+ wasn't stepped up. During the late 1940's til 1960's, Roberts Radio (UK) used the Mullard DF & DK series of tubes with 1.4V filaments which ran from another cell and a string suppying B+ of 90V. Funny enough the other day I saw one of those huge battery packs in a hardware store.
The vibrator (essentially an oscillating relay with a set of contacts intent on creating a polarised voltage found itself in car radios with a notorious short life. Interference was a real bewildering problem. The tubes with a single heater wire as cathode were easy to destroy. Anyone remember all this ??

richy