Nowadays the AC mains network is heavily polluted by various domestic appliances, industrial electrical consumers etc. This can lead to buzzy toroidal transformers (especially the power ones). Proposed DC trap (blocker, filter) will remove or at least lower the buzzing.
Schematic is similar to this one used in well known Vladimir Shushurin’s Lamm-1 amplifier. An article with in-dept explanation of how DC blockers work can be found on Rod Elliot’s site (http://sound.whsites.net/articles/xfmr-dc.htm).
Proposed PCB is a successor of the very successful second version of the board.
It retains some of the previous board specifications:
Dimensions of PCB: 88×94 mm.
PCB type: FR4 1.6 mm. Copper thickness: 70 um (2oz). Surface finish – Nickel Gold (ENIG).
TWO-layer design which allows the current handling capabilities of the board to be doubled.
All current conducting traces are widened as much as possible which additional raise the max. handled current.
PCB has solder mask coating on top and bottom layer for best durability.
Silk screen with parts layout is placed on the top of the PCB.
In the current 3-rd PCB version is incorporated the ability for mounting of 6 high-power discrete diodes which rises the DC blocking voltage up to 2V.
The possible usage of protective diodes (which number defines the DC blocking voltage) is given on schematic below:
PCB has following abilities:
– Variant with 6 discrete diodes with 2 different bodies – DO-201, TO-220 or:
– Rectifier block which can be KBU8K or GSIB2580 types.
– In case one wants to use the variant with discrete diodes but to keep the lower DC blocking voltage one diodes section can be bypassed by a piece of thick wire, as shown on the gallery pictures.
– Electrolytic capacitors are snap-in with lead spacing 10 mm. and max. outer diameter 40 mm.
– Resistor R1 can be 5 or 10W rated power with lead spacing 28 or 53 mm.
– Bypass capacitor C3 is WIMA MKS4 400VAC with lead spacing 15 or 22.5 mm.
– AC input/output connectors can be of the following types:
a) MOLEX 3- or 5-pins terminal blocks
b) 3-pins Barrier Terminal Blocks with pitch spacing 8.25 or 10 mm.
All parts used are easily obtainable from big supplier stores (Mouser, Farnell, Digi-Key etc.) or via e-bay.
Note: the listing is for PCB only – pictures of assembled device is for information purposes only!
Schematic and parts list will be sent to the buyer’s PayPal address after purchase. If for some reason a different e-mail address must be used, note it in the process of checkout.