Description

Picture shows the top of the bare PCB along with an example of a finished PCB (earlier revision shown in the assy pic). This auction is for ONE bare PCB. 2.5-13VDC @ 3A or 13-25VDC @2A Uses: As a 5VDC heater supply for your 300B project. Use your 5VAC transformer tap to get 5VDC (yes it's possible with this PS). No hum pot needed. As a 2.5VDC heater supply for your 2A3 project. Use 1/2 of a traditional 6.3VAC center tapped winding. 3.15VAC will rectify perfectly into 2.5VDC with this board. Convert your amplifier's preamp/driver tubes to DC. Easily convert a 6.3VAC heater to 6.3VDC. Huge improvement. As a standalone power supply for your Squeezebox or Pi project. Any project that needs a heater power supply or a low volt power supply. Heater Circuit: Regulated 6.3VDC from 6.3VAC winding with the use of schottky diodes and super low dropout regulator. Or 5VDC from 5VAC, etc. This isn’t possible with almost every power supply out there. Voltage doubler jumper and trimpot adjustment. Allows for switching between 6.3V tubes and 12.6V tube without pulling out your soldering iron. Simply move the jumper and dial in the pot. A standard 6.3VAC transformer winding now allows the use of twice the tube choices. Go price a NOS 12SN7 vs a NOS 6SN7 and see how this board pays for itself. Huge capacitance for ultra-low ripple. 30,000uF capacitance. 3 amps max heater current. High current components and heat management designed in. Remember you need 1.8X the DC current from your transformer. For example: to power 2 6SN7 tubes for a total of 1.2A, you need a theoretical bare minimum of 2.16A available from your transformer. A safer rule of thumb is 2.0X the DC current. If you're using the doubler, then current get cut in half once more (darn that Ohms law). Two sets of heater outputs. Additional Features: Optional ¼ B+ reference circuit built in. Elevate the heater ground to ¼ of the B+ voltage. Provides for hum free power and cathode protection. If not using the 1/4 B+ ground, a traditional ground is provided. Or, a jumper location is provided to ground directly through one of the mounting screws. Or, solder a capacitor in the jumper location to float the ground. Or, use no ground at all. Basically, every possibly grounding scheme is accommodated. Designed for use with high end audio grade components (Wima MPK series, Nichicon KW series, etc). Small and compact. All this circuitry is smartly arranged on a 5cm X 10cm board (1.97” x 3.94”). Thick PCB with 2 ounce traces. A BOM from Mouser is below. I used all high end components (Wima and Nichicon Audio caps, etc). Full schematic and board layout are above. If you're handy you can wire one up point to point with all the info in this and and skip the need to buy the PCB. Please know your skill level and knowledge of electronics before considering this PCB. If Mouser is out of something try DigiKey. You should be comfortable specifying substitutions, although I do my best to help you out with that below. For example, if a capacitor is out of stock try a slightly higher voltage or capacitance of the same lead spacing and series. Or try another high quality capacitor with the same specs. Also, there's some wiggle room with resistor values of the same wattage. *** The Microchip LDO that's vital to this circuit is usually out at Mouser (and everywhere else I've looked) and has a long lead time. I have some available that can be purchased with this PCB . Quick way to load the BOM below is to do a web search for "Mouser Project & Cart Sharing". Follow the first link and then enter this project ID: cf769db39a Part Value Mouser (2.5V-13V, <=3A) Alternate Mouser (13V-25V, <=2A) Notes C1 .01uF 505-MKP20.01/100/5 C2 .01uF 505-MKP20.01/100/5 C3 .01uF 505-MKP20.01/100/5 C4 .01uF 505-MKP20.01/100/5 C7 .1uF 505-MKP20.1/100/5 505-MKP2.1/100/10 C9 .1uF 505-MKP20.1/100/5 505-MKP2.1/100/10 C10 .1uF 505-MKP4F031003C00JF Optional (1/4 B+ Ref) C5 10kuF - 15kuF 647-LKG1C153MESYAK 647-UKW1C103MHD 647-UKW1E103MRD C6 10kuF - 15kuF 647-LKG1C153MESYAK 647-UKW1C103MHD 647-UKW1E103MRD C8 10kuF - 15kuF 647-LKG1C153MESYAK 647-UKW1C103MHD 647-UKW1E103MRD D1 625-SBLF10L25 625-SBLF10L25-E3 D2 625-SBLF10L25 625-SBLF10L25-E3 D3 625-SBLF10L25 625-SBLF10L25-E3 D4 625-SBLF10L25 625-SBLF10L25-E3 KK3 SK104-PAD 532-513102B25 532-4880M JP1 3X1X2.54 571-3-644456-3 538-15-29-1024 TP1 0-1000 594-64W102 R1 75 603-RSF100JB-73-75R 603-RSF100JB-73-47R R2 300K 603-RSF100JB-73-300K Optional (1/4 B+ Ref) R3 100K 603-RSF100JT-73-100K 66-CMO11003JLFTR Optional (1/4 B+ Ref) IC1 MC29502 998-MIC29502WT LIABILITY DISCLAIMER A person who constructs or works on electronic equipment may be exposed to hazards, including physical injury, the risk of electric shock or electrocution, and exposure to hazardous substances such as lead, mercury, and other inorganic or organic compounds. These hazards can result in health problems, injury, or death. Only qualified persons who understand and are willing to bear these risks themselves should attempt the construction of electronic equipment. By purchasing this item, the buyer acknowledges these risks. Vacuum tubes operate at high temperatures, may contain toxic substances, and may have exposed parts that carry hazardous voltages. There is a risk of electric shock, electrocution, burns, or fires that is inherent in the construction and use of vacuum tube equipment. By purchasing this item, the buyer acknowledges these risks. IN NO EVENT SHALL THE SELLER BE LIABLE FOR ANY SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES OF ANY NATURE including, but not limited to, property damage, personal injury, death or legal expenses. Buyer's recovery from Seller for any claim shall not exceed the purchase price paid by Buyer for the goods, irrespective of the nature of the claim, whether in warrant, contract or otherwise. By purchasing this item, BUYER AGREES TO INDEMNIFY, DEFEND AND HOLD SELLER HARMLESS FROM ANY CLAIMS BROUGHT BY ANY PARTY REGARDING ITEMS SUPPLIED BY SELLER AND INCORPORATED INTO THE BUYER'S PRODUCT. If you do not agree to this disclaimer, DO NOT BUY THIS ITEM.