Project files: Relay-based attenuator

What is it?
This is the board files for my relay attenuator described here.

How big are the boards?
The board measures 3.85″ x 2.4″ (app. 98 x 61 mm.)

What is the status of the boards?
This board is version 1.0. It has been built and tested and I haven’t really found it necessary to make any changes based on the prototype.

Does it use any special/expensive/hard-to-find parts?
Not really 🙂

  • The relays must be the specified Omron G6K 5V version and the ULN and MCP ICs should be in the right packages (SO-IC). All these parts should be available from the usual sources, i.e. Reichelt in Europe and Mouser/Digikey in the US and worldwide.
  • The resistors should be 1% tolerance or better and some of the values are from the E96 range which might not be available in the shop around the corner but should be available from most of the mail order companies.

Anything else I need to know?

  • Refer to the original build article (link) for some additional information and helpful links to Arduino code samples etc.

Download design files here

Related information:
Note: Always read the “intro post” for additional important information about my designs.



2 Responses to Project files: Relay-based attenuator

  1. quydaQuy says:

    Hi quick question, shouldnt Latching relay better?

    • theslowdiyer says:

      Well, I don’t actually know why people choose latching relays 🙂 . I can think of two reasons though – power consumption and interference from the relay coils affecting the signal.

      – The power consumption isn’t a big thing here to me, because the Omrons are already low power – 100mW each. For a battery-powered application it might matter, but for “normal” use it shouldn’t be a problem.

      – The interference could be an issue I guess, but I can’t imagine this would be a major issue. Call it personal preference, but I don’t consider it a big thing unless I actually had experienced problems.

      In any case, the difference between latching and non-latching relays should be the SW control, so provided you change the SW accordingly it should be possible to replace the relays. That said, if I am reading the data sheet correctly there is no latching version of the G6K relay with uniform 0.1” pin spacing, so for this specific case it looks like HW changes are required as well.

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