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 NEW  Bruce Heran outlines the details and construction of his simple DIY 6DJ8 (ECC88) Tube Hi-Fi Headphone Amplifier Project.

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PostPosted: 20 Dec 2010, 03:21 
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Location: Utrecht Nederland
Hy everybody,

I am a sucker for radio in general and I love old stuff. Playing with crystal sets lately I came across some interesting schematics. A transistor amplified crystal set, that doesn't need no battery, but can generate the needed power through the antenna. It uses a germanium transistor, because they can operate at very low voltages, like 600 mili volts still good, silicone needs at least 800 mili volts, better more. I tried this simple schematic and it did work, but only the strong stations would generate enough power for the transistor to kick in. So the stations that are anyway very loud became much louder, but the weak ones wouldn't profit from it at all. Here comes in Gio's Idea to use a strong local station to power the amplifier and a second tank circuit for actual reception. So here is my goal, I wanna power my radio with the local church transmitter, 3 km away from my house and it has 200 KW power. This will be my power source. Than I will build a second tank circuit and use this to listen to my favorite AM station, radio paradijs, only 600 Watts and 15 km away from my house. I can hear it clear with any crystal radio, just not powerful enough to power a transistor. The strong church transmitter is at 675 KHZ, radio paradijs is at 1584 KHZ, so both stations are nicely away from each other, so it should be realizable without them interfering with each other.

Here are some pics of my preparations, the coil is would on a toilet paper roll, 0,5 mm enameled wire, the adjustable capacitor is homebrew out of cardboard and aluminum foil, works good and has about 300 pF.


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Greetings from Holland, Ben

My DIY Audio Projects:
- Single-Ended 12B4A tube amp with ECC802S driver
- DIY Push-Pull KT88 tube amp (OddWatt amp from scratch)
- 832 / GU32 tube push-pull amplifier project


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PostPosted: 20 Dec 2010, 03:50 
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Joined: 28 Oct 2009, 02:34
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Location: Utrecht Nederland
So here is the schematic in question. This amplifier works well, especially cause you can adjust the transistors bias very nicely with those 1 MEG ohm poties. I have a small but mighty collection of germanium transistors and I got always two of one kind so I can try out and pick the best ones by hand.


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Greetings from Holland, Ben

My DIY Audio Projects:
- Single-Ended 12B4A tube amp with ECC802S driver
- DIY Push-Pull KT88 tube amp (OddWatt amp from scratch)
- 832 / GU32 tube push-pull amplifier project


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PostPosted: 20 Dec 2010, 20:59 
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Joined: 28 May 2008, 21:53
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Location: Winnipeg, CANADA
Hi Ben. I can't wait to hear how you make out with this. Great job with the DIY variable capacitor. :up:

Cheers

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[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


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PostPosted: 21 Dec 2010, 01:57 
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Hi everybody,

I started the build, here is the schematic I am actually going to use.

Only difference, I will try to use one antenna. Have fun!


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Greetings from Holland, Ben

My DIY Audio Projects:
- Single-Ended 12B4A tube amp with ECC802S driver
- DIY Push-Pull KT88 tube amp (OddWatt amp from scratch)
- 832 / GU32 tube push-pull amplifier project


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PostPosted: 21 Dec 2010, 05:56 
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Location: Utrecht Nederland
Some more pics: On the little board is the test setup of a Germanium amplifier. It is working best with a AF106, I tried a lot of different Germanium transistors, but those work best IMHO.


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Greetings from Holland, Ben

My DIY Audio Projects:
- Single-Ended 12B4A tube amp with ECC802S driver
- DIY Push-Pull KT88 tube amp (OddWatt amp from scratch)
- 832 / GU32 tube push-pull amplifier project


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 Profile  
 
PostPosted: 21 Dec 2010, 13:18 
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Location: Winnipeg, CANADA
Hi Ben, how many turns is the coils.

I think one antenna should be fine since there is a separate tuner for the receiver and amplifier.

Cheers

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[ DIY Mains AC Power Cable Cord ] - [ Gobo LM1875 Amp Kit ] - [ Tang Band D4-1 Horn Speaker Kit ] - [ Monoblock Push-Pull KT88 Tube Amp Kit ]


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PostPosted: 21 Dec 2010, 13:33 
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Joined: 24 Jun 2010, 00:48
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Location: Christchurch, NZ
Looks to be 10 turns every 5mm on my screen.
The coil spans for 7cm, so 140 total turns per layer. :mrgreen: :lildevil: :mrgreen:

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Dinesh

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PostPosted: 21 Dec 2010, 14:40 
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Location: Utrecht Nederland
Hi everybody,

yes about 140 turns on a toilet paper roll, haha, 120 would have been enough. Here is a picture of the power supply receiver, it gives me about 1,7 volts without load, my germanium amplifier will need at least 600 milli Volts to operate good, but this I should get out of my antenna. Now I have to build the second receiver, it will receive radio paradijs at 1586 KHZ. Pics come soon.


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Greetings from Holland, Ben

My DIY Audio Projects:
- Single-Ended 12B4A tube amp with ECC802S driver
- DIY Push-Pull KT88 tube amp (OddWatt amp from scratch)
- 832 / GU32 tube push-pull amplifier project


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 Profile  
 
PostPosted: 21 Dec 2010, 15:52 
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Joined: 28 Oct 2009, 02:34
Posts: 501
Location: Utrecht Nederland
Hi everybody,

a little off topic, but here are the pictures of my two transistor reflex receiver. It tunes the entire AM band and works rather well, is super sensitive. I am using BC550C, planar transistors, very high gain, very low noise. In combination with an output transformer it can drive speakers. This radio is in daily use.


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_________________
Greetings from Holland, Ben

My DIY Audio Projects:
- Single-Ended 12B4A tube amp with ECC802S driver
- DIY Push-Pull KT88 tube amp (OddWatt amp from scratch)
- 832 / GU32 tube push-pull amplifier project


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 Profile  
 
PostPosted: 23 Dec 2010, 04:14 
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Joined: 28 Oct 2009, 02:34
Posts: 501
Location: Utrecht Nederland
Here are the first pics of the self powered receiver. I have been trying out all my germanium transistors, and the AF106 became my favoritge, it seems to work best with very tiny voltages.


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_________________
Greetings from Holland, Ben

My DIY Audio Projects:
- Single-Ended 12B4A tube amp with ECC802S driver
- DIY Push-Pull KT88 tube amp (OddWatt amp from scratch)
- 832 / GU32 tube push-pull amplifier project


Top
 Profile  
 
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