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Using Battery for 300v B+ ?

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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
 
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.
 
Mickeystan said:
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
 
mark02131 said:
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
 
Vibrator
vibfig1.gif


Spark gap transmitter:
Sparktrans2.png


Hmm.
 
Anyone remember all this ??

I remember, but the one thing that no one has recalled yet is the 0Z4. Anyone remember that one?

Basically there were 3 evolutionary paths. The home radio receiver, the portable, and the car radio. Home radios started out with tubes like the 01A that used a 2 volt battery for the filaments (the A battery) and a 45, 67.5 or 90 volt battery (the B battery) for the B+ (this is where the name B+ comes from) and a 15 or 22.5 volt battery (the C or C- battery) for bias. in the 1930's the Galvin Manufacturing Company (now Motorola) invented the battery eliminator which was a fancy name for a line powered power supply.

There were attempts to stuff all of this into a box and make it portable. This idea didn't take off until the octal "battery tubes" appeared with their 1 and 3 volt filaments. About the same time Eveready figured out how to stuff all 3 batteries into one case and size them so they all ran out at the same time. Portable radios became a reality, and then the 7 pin miniature tubes came out and made them actually portable. Ballast tubes, 117Z3's and selenium rectifiers made it possible for battery or line power in the same radio. The most collectible being the Zenith Transoceanic.

The Galvin Manufacturing Company figured out how to put one of these things in a car so they changed their name to Motorola, Implying motor and music. The early radios used the vibrator mentioned earlier and a specialized transformer to generate high voltage that powered a typical 6 tube radio. Automobiles had a 3 cell battery that delivered 6.3 volts (does that number sound familiar?) from their inception until the mid 1950's. Some car radios were in reality decent sounding HiFi sets on wheels. My first car was a 1949 Plymouth. The factory radio used vibrator power to generate 300 volts of B+, rectified by an 0Z4. The amplifier had two 6V6GT's in push pull delivering about 10 watts to a 6 inch speaker in the dash. I mounted two of these radios in the trunk wired up to 6X9 speakers on the deck lid connected to a Panasonic portable cassette player for some serious mobile vacuum tube vacuum tube rock music in 1970.

In the 1950's cars went to 12 volt electrical systems. The space charge vacuum tube was invented. It ran with 12 volts on the plate but couldn't generate any serious audio power. The germanium transistor solved that problem, so the vibrator based power supply dissapeared from the car audio market. They were still used in some mobile transmitters until the germanium switching transistor made it vanish altogether. Car radios used 5 tubes and one big output transistor. Then the little 3 legged fuses got all of the tubes voted off the island.

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

It resembles a square wave if the vibrator is in good shape and the snubber caps haven't fried. The operating frequency is usually 40 to 100 Hz.

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

The germanium inverters used in mobile tube type transmitters run at 800 Hz to 2 KHz. It is nearly impossible to keep that whine out of the audio system. I tried putting the inverter under the hood next to the car battery, but the whine was still there.

Modern AC inverters for operating AC appliances in the car work by stepping 12 volts up to about 150 volts and then chopping that up at 60 Hz. The inverter runs in the 50 KHz range and can be used to make about 300 VDC with a voltage doubler.

The 0Z4? That was a gas rectifier that had no heater. AC in DC out, no heater required. The glass ones (rare) exhibit a familiar purple glow.
 
Hey Tubelab....

I remember the OZ4 well. Do you remember that 6 volt vibrators were made with 4 pins in an arrangement like the 300B tube meaning two big pins and two small pins. Also, the 12V vibrators had only 3 pins. If your memory is real good, you will also remember it was very common in early 50's car radios to mount the vibrator power supply and the audio power amplifier on the speaker assembly and cable it back to the radio.

MickeyStan
 
A bit of heritage is quite in order. The Radiotron hd bk has (as expected) as massive chapter related to vibrator psu's. As Tubelab mentioned the gerrm transistor, I am fortunate to have some popular ones in my pit. For amusement value only, the one in the centre photo which looks gold plated is one of the earliest produced in the 1950's.
The RF ones OC44 etc had a bandwidth which fell short of the SW band and the others mainly audio OC71 AC128 etc were hard pushed at 15Khz if that.
Of no commercial value, except the lovely low Vbe drop of only 0.2V all germaniums were photo sensitive hence the black paint. Others canned.
It does seem concidental that the modern day SS switching power supply as we know it has it infant days with the old vibrator. A quantum leap.

richy
 

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richwalters said:
... all germaniums were photo sensitive hence the black paint.

Actually, all semiconductors are photo-sensitive. We had a fascinating demonstration of this recently at work. We needed an inverter to produce 5kV at negligible current, so we made a little oscillator with a transformer to step it up to 500V, then added a voltage multiplier to get the 5kV. But it didn't work when a bright light was shone on the EHT diodes in the voltage multiplier. It turned out that what was happening was that the photo-electric effect was producing a small voltage across each of the diodes that was enough to switch off the op-amp controlling the oscillator. A strip of black insulating tape over the (glass encapsulated) silicon diodes stopped the problem.
 
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