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Crossed from: Musical and effects | Clicks: 8203 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Super audio Reverb
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Blue VALUES replaced by values in RED. Blue COMPONENTS removed from circuit. Red components added to circuit...
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Crossed from: Musical and effects | Clicks: 2278 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
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Crossed from: Musical and effects | Clicks: 3234 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Trainwreck Blues tube amplifier for Guitars
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This revision reduced the signal level and
treble response in the preamp for a smoother
sound in both cathode and fixed bias modes.
The power supply was also revised for lower
B+ voltages to the EL84 plates. "This amp was built on the chassis of an
Electar Tube 30 amp, which is advertised
as a 20 watt Class A amp...
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Crossed from: Musical and effects | Clicks: 7263 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Tube circuits for Guitar Amplifiers
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The IRF820 MOSFET has a voltage rating of 500v, it should work well in preamp stages of most tube amps. The 100 ohm resistor is there to suppress H.F. oscillations. If IRF820 is physically close to the 12AX7 plate, you probably won't need it. You can see how the MOSFET is equivalent to a triode: Source = Cathode; Gate = Grid; Drain = Platel You cannot use the MOSFET as a directreplacement for a typical tube gain stage. The MOSFET will not "self bias" like a typical cathode-biased tube stage.The MOSFET is an "enhancement device" while a triode is a "depletion" device. l In this circuit, it is not necessary to use a heatsink on the IRF820. You can if you want..
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Crossed from: RF Receivers | Clicks: 14658 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
One Valve SW Radio reciever
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A regenerative radio works by feeding back a small amount of amplified output of the detector back into the input. Thus it achieves sensitivity far beyond what only a detector could alone. This simple regen radio uses a single tube as it's detector and amplifier; the "Audion". It's a great first project for those wishing to bring back some nostalgia by building one of the first amplified radio sets. Built on a board using point to point wiring and a set of period headphones, it can be a great functional conversation piece...
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Crossed from: FM Transmitter | Clicks: 7359 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Valve 45 watt FM trasnmitter
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The catering better it does not become at straight line from the network 220V but via transformer 220V/220V of isolation and safety 1A. When does not exist the R3, the force of expense is bigger, but respectively is increased also the hum 50Hz, because the simplicity of designing. The control (Audio In) can become from a kasseto'fwno or other powerful source. If it is microphone it will be supposed precedes amplifier so that it acquires a force of order of 8W roughly. Tendency of catering: 220V AC. Frequency of emission at FM: 88~108MHz. Force of expense: max 45W (without the R3)...
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Valve high-gain stereo preamp
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A cathode follower based on the 6BL7 or 6BX7 is ideal for output. I used a mu-follower circuit with no feedback, a 12SN7 as the gain stage, and a 6BL7 as the cathode follower/current source. (I have many old GEs I wanted to use, and converting to 6SN7 means simply changing the hookup to the 24V filament transformer). You might argue that the current source should be a pentode of highest possible gain, but pentodes can be noisy, and one of my design goals was minimalism. The line stage (Fig. 1) is a straightforward mu follower, with medium-mu triode 12SN7GT below and low-mu triode 6BL7GT above. I paralleled both sides of each tube for maximum lifetime and for minimum output impedance. I chose resistors from my junk box, so there is nothing sacred about the values shown...
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Crossed from: Amplifiers | Clicks: 14105 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Valve audio headphones Amplifier
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The tube headphone amplifier in figure 1 is a high current mu follower, with a 12AU7 cathode follower driven by a 6CG7. Both sections of each tube are paralleled to minimize noise. It's a zero global feedback, OTL design of pretty high quality. I use it and like it for Grado, Sennheiser, and Sony headphones. The maximum gain is about 25 dB with the 6CG7, so it pays to watch the attenuator level. This design can be used as a line preamp as well.
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Crossed from: Amplifiers | Clicks: 18678 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Class A 2A3 audio Amplifier
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The input stage is comprised of a both halves of a 6SL7 octal dual hi-mu triode in a differential amp configuration with a 1ma constant current cathode load. I'm using field-effect (constant-current) diodes for simplicity. the diff amp approach was chosen for good power supply rejection, ease of balancing, good gain, and ease of application of *feedback*, if desired (hey, i like to keep an open mind...). It also takes care of phase-splitting right up front.
Note: I've returned the constant current diode cathode to -9V instead of ground in order to avoid the non-linearities about the pinch-off region (Vpo ~= 1.5V)...
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Crossed from: Amplifiers | Clicks: 19915 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
Push-Pull Class A Amplifier
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This stero amp will give you 4-8W/ch of zero feedback triode power for less than a pair of Chinese 300B's ...if you know where to shop. For those of you who are unfamiliar with this lil' tube here's the poop: The 5687 is a 9-pin miniature twin triode (a la 12ax7, 12au7, etc - but with different pin-out). Its specs are quite interesting: mu = 16, gm = 5400uS, rp = 3k, plate dissipation: 4.2W each unit or 7.5W total (3.75W x 2). After playing with the curves (so kindly reprinted in The Parts Connection Catalog) I realized that you could get some juice out of them (these tubes were apparently designed for high current pulse application - hence the high perveance).
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3.5-30 MHz Valve Transmitter
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This transmitter is very stable and will deliver up to seven watts of power with the components and tubes shown. Do not be put-off by valves as they are VERY easy to work with and it seems that there are quite a few valves around. Because no-one wants these obsolete things they may be bought for next to nothing at radio rally's. If you are not too particular what type of valve you want then there are lots of valves available. Above is the circuit of the transmitter including the coil winding information. The oscillator is a simple untuned Pierce oscillator which will oscillate at the fundamental frequency of the crystal. A 25pf variable capacitor between the grid of the first valve and earth will allow the final frequency to be "pulled" a little but I never used this facility...
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Crossed from: RF Receivers | Clicks: 17999 | Votes: 0 | Comments: 0 | Rating: 0 | Rank: 0
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