Interesting low power amp

[mresistor]

Saw this on ebay and it is interesting.

low power tube amp

I'm curious to find out what the power transformer is and the output transformer. I wonder what level of rectified DC he is getting from that pt?

[FYL]

Or how to recycle old AT power supplies...

[mresistor]

Or how to recycle old AT power supplies...

Right, isn't that cool...   I looked at jameco website and couldn't find any power trans that gets the kind of secondary voltage needed to power the tubes... what't the least amount of plate voltage needed for a 6AQ5 to operate?

Do you think he's using something like this for the PT

[moonbird]

Seen this one before -- on one of his sales he posted a schematic of this "model" or something close. Will try to find it if you are interested.

How can I post stuff on this forum are there size limits?? thx

[mresistor]

he's got the schematic posted in the auction.... what I want to know is what is he using for pt and ot?

[FYL]

he's got the schematic posted in the auction.... what I want to know is what is he using for pt and ot?

PT: ex-surplus Jameco 102692
OT: looks like a low voltage Tamura 130B used as a SE OT. Could very well be a PL5.0 5VA model
http://www.tamuracorp.com/clientuploads/pdfs/engineeringdocs/PL5.0-XX-130B.pdf


Full schemo attached.

[eleventeen]

Kind of an odd setup with the power & heater transformers in series and the dropping components and ckt arrangement affiliated with the heaters on the secondary side. Otherwise, pretty conventional. Which isn't in any way a bad thing.

[jojokeo]

I've seen him normally use these torroidal trannies in the link. He uses the other 120 tap for B+ and parallels the two 6V taps. He's also used the 7v trannies and that may be from voltage drop to give maybe 6.5v for the heaters? There's also a lower powered one but it's only $1 less. At $11 ea that's a pretty good price and the company will ship out up to 8 or so w/out raising the price for shipping. The guy is retired I think & seems very nice and answers questions if you ask him, but mine weren't too specific in trying to get building or design info from him. You could always try? I'd be curious what info he'd be willing to give out.

http://www.antekinc.com/details.php?p=18

[mresistor]

So he's using around 115v for B+?   Interesting. I wonder how much total current the two tubes are pulling. Help me out here, how is he getting the hv secondary winding? Inputing on one of the primarys and then using the other primary as a secondary?

  I did ask him if he would identify the two transformers. Wonder if he'll answer with part numbers. Seems like a cool project, and great little amp for noodling softly in the casa.  

This pt is only $20. But I guess if this one were used the amp would be a little more than a half watt out...     

[jojokeo]

Here's how he's hooking up the tranny and it's got the part number on it too. This is a small triple pentode self splitter he made a while back.

[gh1]

Still waiting for my Toroids For Dummies book to arrive. Can anyone explain in simple terms how this is wired? Sorry if this is the wrong area for this post.

[kagliostro]

For gh1

Why don't start a new tread for this new question 

It seems to me that the connection shown on your picture is confusing

Connection A / B /C / D for me mean connection to one of the primary of the transformer that is in the first (upper) part of the image you post

Connections E / F connection to the second primary winding that is used as a secondary winding

connections blue and green are simply parallel connections of the 7v windings

As I can understand you want to obtain both the B+ and the filament voltage from that transformer

so connect

red 1 and black 1 to the line voltage

red 2 and black 2 to the diodes bridge

blue 1 to blue 2

green 1 to green 2

Connecting blue 1 to blue 2 and green 1 to green 2 you must control if you have the right output voltage (7v) there are BIG problems if you connect the two windings antiphase

Connected this way you have the B+ and filament voltage available

Hope I've understand your question

Kagliostro

[FYL]

Still waiting for my Toroids For Dummies book to arrive. Can anyone explain in simple terms how this is wired?

The PT uses a dual 115V primary winding, one is connected to the mains, the other is used for B+.

Any common transformer will also work as an auto-transformer: 10V thru 10 turns on the primary will reflect as 10V (minus losses) on another primary 10-turns winding. Quite effective but dangerous as there's no galvanic isolation.

[gh1]

Thanks

[mresistor]

How can I post stuff on this forum are there size limits?? thx

what I do is host my pics at photobucket and then link to pics directly, you could use any pic hoting service that way.

[jojokeo]

or simply re-size the picture or file with a photo/camera program