What can I build with 3 12v 1A transformers?

[liddokun]

My tech department was recently doing some cleaning, and decided to throw out some transformers. I ended up swiping them to see if they were of any use.
I now have 3 power transformers, each with 117vac primaries and a 12-0-12 secondary. I'm told by my teacher they're all 1A. 

I want to start experimenting with tubes as I've got what I believe a somewhat good base in electronics building. Are there any type of amps that I can build with these transformers?

[svstee]

http://ricktone.rickcampbell.org/cgi-bin/getimg.cgi/Schematic_TubeODrive_1.pdf
Great thread over at ax84. Not an amp, but I'm gonna build one to get more comfortable with tubes, transformers and high voltage.
http://www.ax84.com/bbs/index.php?area=31

[Ripthorn]

Look at some of frequencycentral's recent posts on using submini tubes as amps and pedals.  You would have to adapt the power section, but they might be of some interest.

[kurtlives]

My tech department was recently doing some cleaning, and decided to throw out some transformers. I ended up swiping them to see if they were of any use.
I now have 3 power transformers, each with 117vac primaries and a 12-0-12 secondary. I'm told by my teacher they're all 1A. 

I want to start experimenting with tubes as I've got what I believe a somewhat good base in electronics building. Are there any type of amps that I can build with these transformers?

Hmm sounds like the same type of x-formers I got from my tech department except mine are 20VA.

Your missing a secondary voltage winding. Probabbly 0V, you only have 3 right now.

You could wire it for 12V, 24V or even 60+V (reverse primary and secondary).

I would try experiment with some semi-low tube designs.

[liddokun]

I was thinking of possibly using it/them for a tube pre.

[Zben3129]

You could *possibly* build a complete tube amp with that set,

One transformer serves as the 12v supply for the heaters

One transformer is used to drop the 120v from the wall to 24v (use full secondary). This 24v is the supplied to half of the secondary of the other transformer, and the primary will output 240v.

I am concerned of a few things. having only 12v for the heaters seems to me a problem. 12ax7s run fine off of 12v, but power tubes usually run from the standard 6.3v (EL84, 6v6, 6l6 etc.)

Will the back to back transformers have enough power? Typical amp would be in the 100-200ma range, and at 240v that would be 24-48VA. Not sure how that would work out with these particular transformers.

Zach

[liddokun]

I figured I can run a few of them back to back. Heaters was a concern for me too, as well as max current.

[kurtlives]

Tube amp's don't draw much current (besides the heaters).

Most draw under 500mA.

I use my similar transformers for tube preamps.

[liddokun]

In that case, I think I have something to experiment with for after exams.

[Zben3129]

I think you should be able to pull off a single ended amp. You might be able to run a couple 12ax7 heaters off of one side of the filament transformer (.3 amps) and then a 6v6/el84 from the other with a dropping resistor (.3A,     12v - 6.3v = 5.7v,      5.7v / 0.3A = 19 ohms,       5.7A * .3A  =  1.7watts.    2 watt 18-23 ohm resistor should work).   I think the current draw from 1 or 2 preamp 12ax7's and an el84/6v6 should be alright for those transformers as well


Zach

[liddokun]

Any idea as to what circuits I should start looking at?

[kurtlives]

Design your own.

Grab some 12AU7s or whatever you think will work and start cascading common cathode gain stages. Tweak, add tone control, tweak and on.