Dc filament supply schematic. Current can also be measured without breaking the circuit by detecting the magnetic field associated with the current. The filament supply for the 300B is DC heated with a simple LC filter Simple yes, but with 300b's being expensive, especially the new production Western Electric's a current source has been my go to for long tube life. Ironically, although the amplifier circuit is very simple, the power-supply turned out to be a monster. To improve on this idea I decided to use 5V integrated circuit (IC) voltage regulators for the 300B filament supply. These both receive 6. Using the schemas given in Figure 43, the heater filaments are isolated from the other amplifier components. Please notice the Millet Regulated DC Filament Supply board on schematic & in photos. It occupies two-thirds of my chassis (Photo 2). Initially thought a simple linear supply with a 1084 regulator would do the job, the problem is a power transformer with about 6A winding, which would be I've replaced it. Become a Gold Supporter and see no third-party ads. Our DC Filament Regulated Power Supply kit allows you to easily convert your amp, or install in new builds, for much quieter preamp gain stages in mid-to-high gain amps. Don't wait to be asked. What's my take on the problem? What sounds best to my ears and why? Let's regulate that once! Schematic of Raw dc Supply: ATTENTION: Wiring to Mains Supply - and High-Voltage Tube Amplifiers must be performed by persons trained in High voltage Safe Practice. So, for example, say you have a line stage pre-amplifier that uses 2 x 12AX7s. 2 MHz Klystron | A digitally DC Filament Regulated Power Supply Run your V1 and V2 preamp tubes on regulated DC voltage. 211 filament 3. Oh yes - regarding heater supply rectification in general, if you need a voltage drop somewhere in circuit, be sure to provide some of it by a dropping resistor BEFORE the filter cap. Tube Heater Supply TentLabs heater supply is designed to supply the heaters of indirectly heated tubes. If you only have an analog front end, this circuit is optimized for this purpose. Sometimes I get excited about my latest circuit and after looking for just the right tubes, output transformers, coupling caps, and low noise resistors, the power supply design becomes almost an after thought. . In addition, this kit can alternately be used to power relays, or other low voltage devices that require voltage regulation. TentLabs filament supply is designed to heat DHT's the cleanest way possible, without affecting the music currents generated inside the tubes' heater, see this presentation that explains the advantages of current source filament supplies. This results in a non-uniform luminance in the display due to the variance in potential between the grid and the filament. The module can also be applied to feed other circuits, that require a similar voltage and current supply. 2. DC heating. " I use an $80 tripp-lite surge strip, but I have been considering building an isolated supply. 5A at 6. In indirectly heated tubes, the cathode is a sleeve surrounding the filament heating it; this mechanical separation helps prevent heater hum (50hz or 60hz AC) from entering through the cathode. The fundamental activity of the amplifier is to modulate this DC supply voltage based on the input signal. My previous was a normal DC filament supply. Basically just add a transformer to get a regulated DC voltage in the 1. Looking at the last schematic on that page, I guess I could just flip the polarity of the ripple filter and move it to the lower side of the filament, between the CCS and the raw DC supply. The voltage regulators see the music signal as an "error" which must be eliminated. Their heater is part of the signal flow, it is included in the audio path, hence the heater supply is affecting the sound. Basically just add a transformer to get a regulated DC voltage in the 1. Worst of all their voltage feedback, which is necessary to set the DC output voltage, reacts to the music signal and across the filament. Note that, there is no current flowing from the filament power supply circuit to the voltage divider. In the original SE 300B schematic a solid state filtered DC power supply is used for the 300B filaments. My rule of thumb: Filament voltage + bias voltage on bias resistor (if it exist) + R. 4x larger wattage than counted. Stable Filament Supply Circuit Diagram. If dropping resistors (I use its in both -positive/negative- wire) necessary, use at least 3. ADVERTISEMENT: Radiopaedia is free thanks to our supporters and advertisers. Designed and built utilizing a state-of-the-art power-conversion topology, these units feature surface-mount technology and encapsulation techniques that Jan 5, 2013 · What I'm after is a way to supply small-signal tube filaments with DC. 3V and I am debating which power supply topology to use. 3Vac Tube amp power supply PCB with bias supply An isolated current sensor board to measure plate current using a PanelPilot meter MOSFET follower buffer for class-A2 grid drive an Opamp experimenter board A simple regulated DC power supply / filament supply Tube active crossover High-Frequency filament converter for DHT's The transformer secondary is still AC, now at a higher voltage, but our amplifier will require a high voltage DC supply. PHOTO 2: High voltage/filament power supply section for the 6SL7 and 6F8G. ) 2) do the filament last longer on DC? 3) is the thermoionic emission the same, so the filament temperature, if I power on DC? It looks that the tubes run hotter if i touch them 4) the tube amp sounds better and cleaner but AC noise is still the same when I put my ear close to the speaker. Following a switcher with a linear regulator is a great way to reduce power dissipation and have a clean supply. 3VAC per secondary and the A series dropping resistor drops the output of the supply to 250V. I’m planning to rebuild my 4P1L paralleled amplifier. Of course, you’ll need to add the DC filament power supply. You still need a surprisingly large amount of reservoir capacitance to get the ripple voltage down to acceptable levels; at least 4700uF for one 300mA heater. And dissipate more power and get hotter. Feb 29, 2016 · I've decided to build a custom Dynaco ST-70 style amp based on Bob Latino's VTA-70 schematic (12AX7 drivers). Even though the specified transformer is rated at 6. My newly developed mains transformer for 211 or 845 amps and separate filament transformers for the 211 and 801A. I’ve got 2 45 tubes that are currently ac heated and would like to experiment with dc heating. Using DC filaments can and does get a quieter heater circuit, in theory, but poorly designed ones can add more noise than they're trying to remove. These have been described in a post about my new mains transformers. If the noise in the amp is coming from the above listed issues, then DC heaters won't always solve them. It also Especially a way to supply 6,3V tubes with 6,3V stabilized DC taken from the ordinary 6,3VAC filament-transformer. The last two stages are DC coupled and the output stage uses an ultrapath cap. Time-delay relay (upper-left corner). The circuit uses a UC3872 IC from Texas Instruments (Unitrode), which is designed to run a resonant lamp ballast for fluorescent tubes. TentLabs now introduces a heater module, based on traditional techniques, but with some major advantages over existing solutions. A conventional DC filament supply can be extremely quiet and much simpler. In fact, we need this DC voltage to be as pure and steady as possible. 25V to ~25V range, at up to 5 amps. Audio Asylum - SET Asylum - Single Ended Triodes (SETs), the ultimate tube lovers dream. The voltage difference between filament and cathode can assume uncontrolled large val Stable Filament Supply Circuit Diagram. The 211 filament is powered with an ultrasonic source. The heater wires are not twisted together, so I'm wondering if replacing them with a twisted pair will be sufficient in getting rid of the hum. I’ve got a 5v 5amp regulated power supply completely separate from the main transformer. 3Vac For more filament power, one can choose a filament transformer (low voltage rectifier transformer) with a "resistive" rating of at least twice the DC current needed and about 4V (or more) higher voltage rating than the desired filament voltage. I wish to try filament bias this time , and I built a DHT filament power supply for 4P1L project. The transformer secondary is still AC, now at a higher voltage, but our amplifier will require a high voltage DC supply. I prefer to heat the 300B filaments with the cleanest possible DC. The 5Y3-GT rectifier filament is powered by a separate 5V AC winding on the power transformer, and the tube filaments and dial lamps are powered by another 6. Anyway, here's my problem: the amp has a DC filament supply for two of the preamp tubes, but 3 of the 4 filter caps are shot (this amp could only be 6 years old or so, as they only made amps from ~2005 to 2010): The filament supply circuit looks like this (From a schematic the Madison was partly based on): Note C71 and C73. In my dive into the beautiful dht tube I was thing about dc heating. Hoffman Amplifiers Tube Amp Forum, Anyone ever gain anything from running amp filaments from DC? The "auto-bias" referred to in the schematic is a small SS circuit I've designed in SPICE that still needs to be vetted in actual use. C. The supplies generate a very low noise output, while maintaining its' high output impedance. It contains a buck regulator stage, and a push-pull resonant controller. I am designing two tube units with a filament current requirement of about 3. 3V AC winding. From the schematic above, I used a capacitor multiplier to supply the +Ve side of filament, and another constant […] TentLabs filament supply is designed to heat DHT's the cleanest way possible, without affecting the music currents generated inside the tubes' heater. The Tentlabs module would provide the -85V to bias the grid, while Rod Coleman's module would supply the 5v for the filaments (see schematic below). Any opinions? Thanks, -FunkyE9th The power supply will be a bit more difficult since it uses more heavy components: Three power transformers. I'm going to build the amp into separate power supply and driver/output chassis. The voltage reference can be given to the filament power supply circuit using the centre tap of a centre tapped transformer. Devices, at the circuit level, use various techniques to measure current: So I'm thinking of putting a rectifier on heater supply. poorly soldered connections allowing more signal bleed etc. Thanks to the fact that the supply works with a constant load, it can do without special protective circuits and the additional complexity of optimum regulation characteristics for dynamic loads. This will mean drilling holes in that collectible amplifier, and finding a spot to add the power supply circuit board. Maybe even in RIAA-amps, depending on what low level of ripple may be achieved. The connection, from the voltage divider and the centre tap, just sets a common voltage reference. This line of regulated DC-DC converters addresses the needs of the high precisio and high stability power supply user. Electric current can be directly measured with a galvanometer, but this method involves breaking the electrical circuit, which is sometimes inconvenient. While AC heating is ok for 45 or 2A3 amps, with the 300B I want DC for absence of any modulation of the signal by the filament supply. The Western Electric 300b's will last a very long time in regard to The filament (AKA heater) supply, on the other hand, is something new for those used to indirectly heated tubes. Confusing DC filament circuit Great question Phil. Do silicon diodes have a ramp-up voltage threshhold, where 'low' voltages may sneak through? Terrible Amplification & Sawdust Concern - Custom Valve Amplification, Effects & Hardwood Accessories - made in Melbourne, Australia FB: terribleamps DHT Filament supply Despite their massive linearity, Directly Heated Tubes (DHTs) have one major disadvantage. But then I look at schematics of other amps and they are not using DC heater supplies and are quiet. The filament of this klystron is floating at cathode voltage of -100 kV dc, | Filamentation, Power Supply and Electric Power Supplies | ResearchGate, the professional network for scientists. While current regulated filaments are quite popular and work well, I still prefer a purely passive approach with an LCL supply. Especially a way to supply 6,3V tubes with 6,3V stabilized DC taken from the ordinary 6,3VAC filament-transformer. Is it a placebo effect? Really, an inductor in a dc circuit is absolute witchcraft to me, not just in the filament supply but in the B+ What I know about electricity would tell me that a choke in a dc circuit could also be accurately described as "a length of wire. But like this it is a bit difficult to get an entry point for line level sources, since the output stage is DC coupled. on-isolated precision filament supply. Its' main use is feeding phono and line stage tubes, to keep the hum levels down. This implies that there is no common voltage reference and the filament voltage is floating, with respect to the voltage of the other amplifier components. B+ Power Supply Circuit Click On A Section of the Schematic Below for Information on That Part of the Circuit: Thinking about using a Tentlabs negative bias module in combination with Rod Coleman's Filament Supply, to fixed-bias and dc-power the filaments of a DHT. Download scientific diagram | Schematic diagram of filament power supply from publication: Design and Development of DSP Controlled Filament Power Supply for 1 MW, 352. The never ending battle of AC vs. With the DC drive method, a resultant filament potential exists across the width of the filament. Putting a bridge-rectifier on the AC leaves you with around 8,8VDC, non-stabilized, far too little to apply ordinary linear 3-terminal regulators (MC7806 etc. Using the schemas given in Figure 43, the heater filaments are isolated from the other amplifier components. A schematic, layout, and hi-rez pics are very useful for troubleshooting your amp. From the schematic above, I used a capacitor multiplier to supply the +Ve side of filament, and another constant […] If you like using a VariacTM with your vintage Marshall, a regulated filament supply is a worthwhile add-on. I've quietly wondered the same thing in the small handful of applications I've used a DC heater. reg headroom (variable of versions) == raw DC voltage (output of raw supply). Input/driver filament Table 1 shows the power-supply parts list. This has worked great (with remote Bourns 10T pot) with my Flexi-Amp for my mono system, which takes most DHTs and even 46 tetrodes with a 417a driver with CCS on top. Been looking at various DC filament supply components from TentLabs and others, and they all strike me as a bit of overkill for anything but high-end audiophile applications. JUST DO IT! - However, if You leave the filament floating (AC or DC), meaning that you do not ground it at the transformer center tap or at one side of the filament supply, we will experience a lot of avalanche noise on the loudspeakers. You can connect two modules to get a bipolar supply (for opamps, for example) - see below. Next, careful lead layout will have to be followed. Here is the schematic (click on the image for a full PDF schematic): Explore a DC filament supply schematic for electronic circuits to power vacuum tubes and other high-energy devices efficiently and effectively. Reviews Read what Dick van Merwe A cheap trick is to supply only the input valve heater with DC while the rest still receive AC. This is not a question of the merits and downfalls of dc heating, more of a circuit question. hcuu, 6woag, xuvavw, 8g45r, i1lmfw, mao11, 3e2n, uac5n, 95dj, 7hgr,