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rjm rjm is offline

Richard Murdey

diyAudio Member

About Me

  • About rjm
    Canadian citizen, Japanese resident.
    Audio Circuitry
    Research Scientist
    Real Name
    Richard Murdey
  • Signature
    RJM Audio ( / G+)


Total Posts
Blog - RJM Audio Blog
  • Wiki Contributions: 0
  • Wiki Comments: 0
  • Recent Wiki Activity: rjm has no recent wiki activity
General Information
  • Last Activity: Today 01:25 PM
  • Join Date: 2nd May 2004


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View rjm's BlogRecent Entries
Latest Blog Entry

Posted Today at 07:02 AM by rjm Comments 0
By request.

Simple 4 option loading for MC or MM cartridges. Stereo board, 80x50 mm. Part of the "useful elements" series.

Inputs are bidirectional (pass through), the signal only has to be connected to one set to function.

Posted Today at 05:33 AM by rjm Comments 0
I'm sure there are dozens of people on diyaudio who could do up this layout, but hey, it was sitting there waiting for me to do and it took all of half an hour ... so to continue the series of 50x80mm "useful elements" boards, here is a simple bridge rectifier board for a transformer with two secondaries.

It will work with just about all of my projects.

If there is interest I may get a set made up, or make the Gerbers available.

Posted 27th December 2016 at 01:33 AM by rjm Comments 0
Two boards, each board configurable for line and headphone variants. Powered by nominal +12 V -12 V split regulated supply, though 9-15 V rails can be used without modification.

Posted 23rd December 2016 at 06:02 AM by rjm Comments 0
Following on from this post and this post, we arrive in time for the holidays with Project Unity. Merry Christmas everyone.

Four circuits: Unity, Unity H, Unity B, Unity BH. line preamp, Headphone amp, line Buffer, Headphone Buffer respectively, all derived from a common base circuit called Unity Root. Unity Root is conceptual, it exists only as a reference so you can see more clearly how the four working variants relate to each other.

It's the "all for one, and one for all" approach to diyaudio, a single research and development line applied to a range of applications, feedback from any of the applications brought back to apply to the line in general.

This simplifies not just the circuit development, similar efficiency is also brought to the documentation, board layout design, and BOM... about which I'll have more to say in a bit.

Posted 20th December 2016 at 05:47 AM by rjm Comments 0
I've come this far so I might as well complete the trifecta.

This is the X-Reg circuit, with a new layout and component numbering to match the new S-Reg and Z-Reg boards. Each is a drop in replacement for the other.

Like its siblings, the X-Reg is a low current voltage regulator for line level audio. The output is about 9 V (adjustable up to 12 V) and the maximum load current is 50 mA without heatsinks, 100~150 mA with small heatsinks on Q1,2.

It is not a true regulator as there is no fixed reference and instead the output voltage is defined relative to the input voltage. The high open loop gain of the op amp is harnessed for very low noise and very high ripple rejection. It is necessarily a high feedback approach.

So, there you are: three mix-and-match power supply options for all your low voltage, low current audio needs.
Recent Comments

Posted 19th December 2016 at 09:35 PM by rjm rjm is offline
I like...
Posted 19th December 2016 at 03:09 PM by dimkasta dimkasta is offline
Any updates?
Posted 22nd September 2016 at 04:49 PM by Ropha3r Ropha3r is offline
Thanks. Nice diagram,...
Posted 8th August 2016 at 06:35 AM by rjm rjm is offline
It's a very simple design....
Posted 8th August 2016 at 06:15 AM by FritzS FritzS is offline
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