Main 1176 Page

Rev J 1176 Clone Boards
Professionally Manufactured 1176 Clone Boards

Revision J
I've reworked my G1176-type boards to allow greater flexibility in wiring the input and output transformers. The new boards will allow you to wire the input transformer as 1:1 or 2:1 and the output transformer as 1:2, 1:1 or 2:1. The boards are configured for a "normal" configuration of 1:1 input and 1:2 output without any modification. Other configurations are simply a matter of reversing the transformer. More options are available by adding wire links and cutting specially designed traces (which are made so they are easy to cut).

The Revision J (my own lettering system) boards also incorporate all the following features from the earlier revisions:

  • The ability to mount several different output transistors. All that is required to fit the original Gyraf specified BD517/518 transistors is to add two small wire jumpers to the board. The common replacement transistors BD135/136 or BD139/140 can be used without the jumpers. No need to twist leads and use shrink tubing to use either transistor pair on my boards.

    Rev H Output Transistor Footprints
  • Options for either OEP or Lundahl input AND output transformers. You can use either OEP or Lundahl in any combination - they all drop in and require no modification to the board traces or wiring
  • Lundahl output transformer is wired 'reversed' to increase gain to the equivalent of the original UREI 1176. OEP is wired natively (its ratio is 1+1:2+2 primary to secondary) for the same result.

    mnats Board With OEP Transformer
    mnats Board With OEP Transformer

    mnats Board With Lundahl Transformer
    mnats Board With Lundahl Transformer

    No additional wiring is required to use either transformer.

  • Star grounding scheme isolating the various sections of the circuit and bringing them separately to the star point beneath the output transformer for elimination of hum
  • Additional pad for stereo interconnect between two units
  • Most styles of trim pots can be installed on the one board and in any combination. Virtually any style of trim pot can be used - multi-turn, miniature or traditional 25 cent trimmers drop in to the board without modification

    Standard Trimmer

    Mini Trimmer

    Multi-Turn Trimmer
    Various Styles of Trimpots Simply Drop In

  • Better component 'footprints' for easier component insertion and less chance of damage to delicate parts such as glass diodes
  • Better pad designs for increased 'grab' on crucial components, off-board hookup wires and in/out cables
  • More room for power supply capacitors - no more crowding!
  • Additional ground pad for hum-free off-board wiring
  • Thorough labeling of various pads that connect to other parts of the circuit

    These new Revision J boards are now available pre-fabricated. The boards are professionally manufactured with full silkscreen component legends and solder mask.

  • PCB: 1 layer with solder mask, overlay.
  • Material: Fibreglass FR4 .062" thick, 1 oz. copper.
  • Finish: Hot Air Solder Levelled (HASL)
  • Component overlay: White
  • Solder masking: Green Liquid Photoimageable Ink (LPI)

    With the main board I also provide a redesigned meter board and ratio board for the rotary switches used in the original Gyraf design. The layouts are slightly larger than the original Gyraf boards and are also fully and clearly legended for ease of construction. They will fit both Lorlin or Alpha rotary switches.

    I now also include one Power Supply Board per board set.

    Ordering details at the Board Ordering Page.