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Old 5th May 2002, 11:19 PM   #1
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Question Need some help here,please - 3V only amp!

Hi!

I found these schematics for a 3V amp and i would appreciate some help, please.

Here's the url: http://www.triodeel.com/3vhifi.gif

What do you think that the transformers, for stepping up the voltage and audio, should be? This guy must be joking about a crazy 30W (i guess) audio amp for such a tiny thing!
I'm going to get the tubes tomorrow.

Bye! (and thanks!)
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Old 7th May 2002, 03:10 AM   #2
PassFan is offline PassFan  United States
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The circuit you provided the link to has the transformers listed and is a battery powered circuit. What transformers are you talking about.
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Old 7th May 2002, 10:04 AM   #3
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HI!
I'm talkning about the step-up and 6v transformer. It says about a 6v filamente xformer. Ok, but, what V primary? The secondary is 6v, but what the rest? The output transformer for impendance matching is not such a big thing. Does a regular and simple one with 6.6k/8ohms do?

Thanks
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Old 7th May 2002, 04:18 PM   #4
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I am very skeptical. Was this schematic posted on April 1st?

This amp uses a Hammond 1650P "Heh Heh" What is a "Heh Heh"?

I just do not see how you are going to get any power out of a tube amp that is powered by 2 AA batteries.

Maybe I have something to learn

Duracell's AA battery model number is MN1500. Here is some technical data.

http://www.duracell.com/oem/Primary/...lkcapacity.asp

Looks like to me, you can get 3 volts (2 AA in series) at 3 watts (audio power) for aboutt 1 hour. Then you have to supply the heater, for 1S4 tube - .1 amp. That is off the scale.

Maybe the batteries shown just for simulation purposes. The designer expects you to use a more conventional power supply.

Let us know the results.

Aud_mot
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Old 7th May 2002, 05:11 PM   #5
PassFan is offline PassFan  United States
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The primary of the filament transformer I would assume would be 120 volts. The output impedance on a 1650P is selectable to match what ever speaker you use. There appears to be a transistor in the filament circuit and this may have something to do with voltage gain for the filament transformer. This looks like a schematic from Steve Bench. You can catch a link from triode electronics to his site and check it out. He has a few battery powered amps and also explains their operation in detail. This isn't a dirt cheap project for someone not used to pricing this stuff. Your transformers alone will run you around 160.00 bucks. Cheap by tube standards but you won't build it for 50.00 bucks either. Good Luck.

P.S. Angela Instruments has good prices on the transformers. There is a link to them on the home page of this forumn.
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Old 15th May 2002, 11:27 AM   #6
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RCA Recieving tube manual data/heater fil=1.4V .1 amperes/plate volts=45/grid bias=-4.5V/ screen volts=45/screen grid current=.8mA/plate current=3.8mA output watts=.065 That is class A SE. Very low power -power pentode is the 1S4. Maybe a SE earphone battery operated amp? Hook it up to a Walkman? Says 3V( input?) which about right for CD
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