Sola 71542 Constant Voltage Transformer - what to do with this ? - datasheet ?

[kagliostro]

From a Jerrold 900-B Sweep Generator that a friend disassembled I got some parts as a present

there is a very nice Power Transformer, a Sola 71542 Constant Voltage Transformer
(someone knows were to find a datasheet ??)

it has a winding to which is to be connected a cap to stabilize the voltage

(sometime ago someone here into the forum found a similar power supply for low voltage and PRR explained about the use of that cap - many thanks for that, now I know what I have under hand)

the transformer has double windings to be "perfect" for 50Hz & 60Hz use (there is a connector to be plug in the right outlet) and also a switch for 115v / 230v commutation of the primary

there are 3 different windings for filament supply

to the first one there are attached tubes for a consumpion of 2.72A

to the second one there are attached tubes for a consumption of 1.865A

to the third one there are attached tubes for a consumption of 0.270A (and a connection labeled 1A NOT USED)

the High Voltage (B+) after full-Wave rectify and filtering is 275vDC no idea about current available

the tubes used were throughout 14

3 x 6au6 - 2 x 6cw5 - 3 x 6922 - 1 x 6dj8 - 1 x 12at7 - 1 x 12ay7 - 1 x 6cb6 - 2 x 5675

this is my question:

What can I do with this Constant Voltage transformer ?

Have you any idea ?

I don't think this transformer (also if it is big and heavy) has a large B+ current available

Thanks

Kagliostro

p.s.: the cap with the yellow dot to be used as "stabilizer" is C1 1.43MF

[eleventeen]

Not especially useful for amp use (or much of anything else) There is no B+ winding, the secondary is close to a 1:1 to the primary, there is a low voltage winding that powered a circuit that functioned as a ferromagnetic regulator. You can look up how it works "constant voltage transformer" and get a better explanation than I can provide. They typically hum a lot, generate heat, and are big! They are somewhat less than useful because whatever regulation they provide is available better and cheaper via electronic regulation once the line voltage is rectified to DC....the low voltage regulator doesn't have to handle as much power, and of course, 3-terminal regulators are available that do the job in one "chip" + 2 capacitors. Better, cheaper, smaller, less heat, no hum. Better in every way you can imagine. It is only those applications where the line voltage itself must be regulated...and there aren't all that many of those these days.

Sigh, another once-impressive device one not only doesn't see too much, but also has almost no utility any more.

[kagliostro]

Many thanks Eleventeen

I was hoping to use that PT for a stereo guitar preamp, as in B+ rail I think there is not very much current and also if the voltage is only 275v

but your explanations do not leave me hope 

Kagliostro

[PRR]

> There is no B+ winding

There were "line regulators" made for 95V-140V in and 115V out.

But SOLA would also custom-wind whatever you wanted. DEC computers were full of 50-pound SOLAs wound 8VCT to make +5.25V DC for logic systems. This one is wound to make 275V DC either side of a CT, as well as a 6.0V heater winding.

Note that after SOLA regulation, this gear also has gas-tube regulation for steady 150V. Someone was VERY concerned about steady DC. Ah... it is a wobbulated signal generator and detector for aligning TV RF tuners in a factory.


It will deliver +275V at 35mA and also -270V at 18mA.

You could probably take just the +275V at 50mA.

That is 13 Watts DC, maybe 6 Watts audio output. Champ or under-size p-p 6V6/6AQ5.

You could take 550V at 30mA. 16 Watts DC, possibly 9 Watts audio, but the p-p- load impedance should be 36K(!) and there are not many low-watts high-volt tubes.

I do not see what advantage the Constant Voltage has, for guitar amps, unless you have severe wall-voltage variations.

It may also hum loudly, acoustic vibration from the saturated core.

It may not work at all well without that special cap.

[kagliostro]

Thanks PRR for your supplementary information

all you say is sane, that is a very difficult to reuse PT, I think nothing will be done with that

the transformer is heavy and the HUMMMM feature is surely not wanted

Kagliostro