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Vacuum Tube Circuits

Vacuum Tubes:  #'s - F        G - R        - Z

 

Last Updated: June 02, 2021 01:44 PM

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1 Valve CW transmitter  -  This transmitter was first constructed in 1987 and provided the author with his first 'real' rig, capable of distances of more than about 100 metres.  It performed better than expected, with 250km contacts being commonplace and 2500km being occasionally possible. __ Designed by Peter Parker VK3YE

2 Valve 40m CW Transmitter  -  amateur radio construction projects.  circuit only, no description given.   __ Designed by Peter Parker VK3YE

25 Watt Music Amplifier  -  schematic only, no description   __ Contact IQ Technologies

2A3 Push-Pull Class a Stereo Amp  -  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'vereturned 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)  __ Designed by Bobanielak

40-30 CW Transmitter (Tube based)  -  This project involves the construction of a three-tube ham radio CW (morse code) transmitter for the 40 and 30 meter amateur radio bands.  The tube set includes a 6AU6 preamp, a 5763 driver and a 6L6GC power amp.  Output power is around 20 watts with a 500V B+ supply.  The transmitter is driven by an external DDS VFO and can operate in full break-in (QSK) mode.  Your author frequently uses this transmitter to communicate from Colorado to stations on the East and West coast of the US using a simple dipole antenna. __ Designed by G. Forrest Cook

5 tubes SSB QRP Transceiver for 20m Ham band  -  A 5 tubes SSB QRP Transceiver for 20m Ham band - The complete schematic shown here includes the supply section, but omits the low-voltage part needed to drive the relays coils.  I'veused a voltage doubler from the 6.3VAC of the tube heaters because I chose 12V relays.   __ Designed by Andrea  IW9HJV and Johnny  IW9ARO

500W 4X150A/7034 Tube 26-30MHz VHF output Amplifier  -  The more information about tube 7034 can be found at this address http://www.  g8wrb.  org/data/Svetlana/pdf/4X150A.  pdf Shortly: The heater voltage 6v 2.6Amp.  You can see the yellow light in it.  All metal/ceramic construction.  First apply the 6v heater voltage 30 second before the anod voltage.  Sufficient cooling must be provided for the anode.  The best is to use an anode chimney.  Air-flow is in the base-to anode direction __ Contact IQ Technologies

6B4G Integrated Mono  -  The amp is based on Ralph Power's simple iT-coupled PP amp.  However, being a Fixed Bias Believer, I converted both stages to fixed bias.  Output stage uses a conventional power supply for biasing; first stage, 6C45P into LL1160 (Alt-U wiring) , is biased with an inline lithium button cell to 220.  .250V, 25.  .30mA.  This is probably unsafe.6C45P usually requires a low resistance grid-to-ground path (150K or less by the book) for stability.  Here, it's up to 300K plus battery.  As if it's not enough, Ua is 100V above rated maximum and PA is close to maximum.  So far, it's stable.   __ Contact (c) klausmobile

845 20W A1 class Monotriode Amplifier  -  This project is finalized, that means it is no longer experimental.  This amplifier, altough limited in output power (20W) , has been designed to give the best listening pleasure.  No compromise has been made during components choice: the 845 output triode is one of the best tube available today in that range of power for single-ended applications, the driver stage uses a 300B, a long revered audio tube (note that you must use a WE 300B or a Sovtek 300B).  This technical choice has been made in some commercial (like Marantz T1) or amateur  __ Designed by puechmor @ mygale.org

A Vacuum Tube Microphone Preamp/ Direct Box Project  -  From January 1997 EQ Column, includes phantom power supply__ 

Amp based on a Silvertone Twin Twelve  -  ampbased upon an old Silvertone Twin Twelve -- I decided to try another guitar amp (actually, I intend to build two identical single 12" combo's - one for me and one for my TWiN brother, Rich).  Although  I'm sure a Fender Deluxe knock-off would be just fine for what I needed , I wanted to do something a bit different __ Designed by Bobanielak

Baby of Camel: All-directly-Heated Pushpull Amp-Spy Photos  -  Project a Camel is a take-no-prisoners DHT PP based on Lynn Olson Aurora topology.  Unfortunately,  I'm stuck waiting for Lundahl transformers (three months that famous Nordic attention to detail one turn a day).  Well, before Camel is born, there was his baby, sans interstage transformers, yet with all DHT stages (all tubes from Svetlana 1970-s).  OK, the input/splitter __ Contact klausmobile @ yahoo.Com

Bass Guitar Amp  -  I've been wanting to put these EL509's to use! ! !  Figured a nice high-power bass guitar amp would be a perfect application.  I have the amplifier built to the point shown in the schematic, above.  Initial testing with tone-stack replaced with a 10:1 voltage divider is very promising.  Still need to decide on the tone stack arrangement.  The unit is built as a stand-alone head, and will be used with a Peavey 15" + 2x 10" Bass cabinet __ Designed by Bobanielak

Battery heaters in a tube Amplifier: a Simple Circuit battery switch with undervoltage protection  -  This simple circuit controls 6.3V SLA heater batteries (two batteries are shown, but it is stackable to practically unlimited number of batteries).  Batteries are floating in 'on' state, paralleled in 'off' (external charger) state.  If any battery voltage falls below threshold for more than 1 second, the circuit latches up in 'off' state, disconnects the batteries and shuts down plate power supply (which is normally controlled through a delay relay).  Once in 'off' state, it can be reset to normal only with master mains switch.1-second 'grace period' set by C2R2 takes care of power-on surge currents that can cause temporary undervoltage __ Contact Klausmobile Tube Tester Files

Capacitive Sensor  -  Special design for shop-windows animation; Useful for many types of touch controls __ Contact Flavio Dellepiane, fladello @ tin.it

Class A2 SE 812A Amp  -  This Amp is a variation on the SE 826 amp, below.  It uses positive grid bias derived directly from the cathode follower driver stage.  The 6F8-G driver/input tube was chosen because it biases to the required voltage (+14V) for the output stage's bias. (Note that the 6F8-G can be replaced with a 6SN7.  I just happen to like the looks of the 6F8-G better)  __ Designed by Bobanielok

Class A2 SE 812A Amp power supply  -  This is the power supply for a Class A2 812A Amp __ Designed by Bobanielok

Class A2 SE 826 Amp  -  The schematic for the SE 826 amp.  This Amp was an attempt to create a nice Class A2 power amp, similar to the SE 833 amps, described below, but without a 10:1 step-down transformer.  Instead, it uses a choke-loaded cathode follower to drive the output tube.  It uses positive grid bias derived directly from the cathode follower driver stage.  The 6F8-G driver/input tube was chosen because it biases to the required voltage (+14V) for the output stage's bias. (Note that the 6F8-G can be replaced with a 6SN7.  I just happen to like the looks of the 6F8-G better)  __ Designed by Bobanielok

Class A2 SE 833 Stereo Amp  -  The schematic for the SE 833A amp is shown HERE.    __ Designed by Bobanielok

Class A2 SE 833 Stereo Amp Power Supply  -  The schematic for its power supply is shown HERE.   __ Designed by Bobanielok

Class A2 SE SV572-160 Stereo Amp  -  This amp uses a 6BM8 drive stage similar to the big 833A amp below, except it utilizes CATHODE drive.  I presently have this amplifier set up so I can adjust the grid bias from about +2V to +30V.  There is also a switch that connects the output tube grids to ground (0 Bias) instead of the grid bias supply.  This way I can experiment with various output tubes, including 811A, 812A, SV572-10, SV572-30, SV811-10, etc.  So far, I think the SV572-160 sounds best in this amp.  I think it is because of the cathode drive (also called grounded grid) topology.  I think I like the medium mu transmiting tubes, like 812A, 826, SV572-30 in grid drive amplifiers better.  But in this amp, the 572-160 can be "dialed in" to a nice sweet-spot that sounds great!  __ Designed by Bobanielok

Class A2 SE826 power supply  -  The schematic for the power supply __ Designed by Bobanielok

Closer look at the FET booster based on a vintage Fender 12AX7 input stage.  -  in the two years since the Fetzer Valve was first published in the midst of our adaptation of tube amps for use as distortion pedals, the circuit has enjoyed popularity as a standalone booster and as a building block in larger circuits.  While the circuit has its merits, we decided to further explore it to determine if it was a truly faithful solid-state version of the familiar input stage used in many tube amps. __ Contact holler @ runoffgroove.Com

Convertible Single Ended SV572-30/3 Stereo Amp  -  This project makes use of at least two of the new SV572 series audio power triodes from Svetlana.  This series includes the SV572-3 , SV572-10 , SV572-30 , and SV572-160.  The circuit topology is easily re-configurable ("convertible") to use either the -30 (in Class A2 - Zero Bias operation) or -3 (in Class A1 operation).  In addition, the -30 can be configured for two different drive schemes (standard grid driven configuration or Cathode Driven.  A set of switches are used to reconfigure (with power off).  But for clarity, the schematics are re-drawn for each mode as shown below __ Designed by Bobanielak

Darling & DC Darling SE 1626 Amps  -  This has become a very popular set of amp designs.  They are all based upon the 1626 Triode output tube and the philosophy to keep things SiMPLE.  I am continually amazed how good these amps sound for what they are.  The name "Darling" came from a good friend's description of my original design.  It looked like a miniature version of "full-sized" SE 300B.  The name stuck  Click  HERE  to find out more __ Designed by Bobanielak

DC Coupled Phono Preamp  -  Schematic, Only     Using 6SL7 instead, and DC-coupling of the two stages.  RiAA Preamp based upon the classic RCA 12AX7 design.   __ Designed by Bobanielak

Dekatron-device used for dividing by 10 during the valve era  -  The circuit diagram is almost the same as Mike's.  I added an ON/OFF switch and an additional toggle switch to stop the spin.  The resistors are standard types (according to Mike I should've used higher power ones to ensure adequate voltage rating) ; the capacitors need to have sufficient voltage rating.  I didn't have anything rated 400V so I used two 330nF capacitors in series in two places.   __ Designed by Hans Summers

Direct Coupled 15 Watt Amp  -  Schematic only, no circuit description __ Contact IQ Technologies

Eight Simple Circuit power supplies for your workbench (mainly vacuum tube based)  -  The power transformer is what isolates the output terminals from the line and makes it safe.  If you can't find a particular transformer there are several alternatives among the circuits.  A transformer you already have or one you can get may determine which circuit you build.  The circuits that use a 5Y3 rectifier tube require a transformer with a 5 volt 2 amp winding for the tube's filament.  If you can't find or don't have a transformer with a 5 volt winding one of the 6AX5 circuits may be for you. __ Designed by Max Robinson

Five by Twenty SSB QRP Transceiver  -  A 5 tubes SSB QRP Transceiver for 20m Ham band - The complete schematic shown here includes the supply section, but omits the low-voltage part needed to drive the relays coils.  I'veused a voltage doubler from the 6.3VAC of the tube heaters because I chose 12V relays.   __ Designed by Andrea  IW9HJV and Johnny  IW9ARO

Five Tube Stereo Amplifier  -  This 5 tube stereo amplifier is based on the output stage of your typical late 1940's 6-tube AM radio amplifier design.  Its simplicity invites a little experimentation from those who enjoy tinkering. __ Designed by Wes Kinsler

FuzzniKator Push-Pull Tube Distortion/Preamp  -  improved tube distortion project __ Designed by G. Forrest Cook




Vacuum Tubes:  #'s - F        G - R        - Z


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