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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: Yesterday 11:23 PM
  • Join Date: 2nd May 2004


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View rjm's BlogRecent Entries
Latest Blog Entry

Posted 18th February 2017 at 03:53 AM by rjm Comments 0
The classic VSPS slightly updated and fitted with a simple filtered Zener voltage regulator (Z-Reg).

Relaxed, spacious, easy to work on 80x100 double sided mono circuit boards.

The eagle .sch and .brd files, LTSpice .asc file, and Gerber zip package are all provided below.

Works fine with the NE5534A, or use whatever op amp you choose.


revision and edit history:

200a initial release
200b changed to 70x90 hole spacing
200c C3 package changed to PCM37.5, updated C3 part listing in BOM to Kemet
200d changed regulator back to the Z-reg add R9,10 to BOM
200e move C1 and C2 capacitors 90 degrees
200f further layout tweaks
200g even more layout tweaks
200h are we done with this yet?
200i - skipped -
200j - skipped -
200k removed brestrict layer and re-did the power planes using only rect/split
200l - skipped -...

Posted 15th February 2017 at 11:11 PM by rjm Comments 0
The RJM Audio Phonoclone phono stage circuit has not changed since the first board was produced. The previous iterations just refined the layout and applied various approaches to the voltage regulation.

Most of you are probably only aware of the X-Reg sporting Phonoclone 3, but there were actually quite a few earlier versions with LM317 and LM7812 regulators.

The Phonoclone 4 applies a major revision to the board layout, making it more logical with grouped, standardized I/O connections. The X-Reg has been replaced with the S-Reg shunt regulator circuit. Overall the BOM has been considerably simplified and the parts cost reduced.

For the moment, the boards are back-compatible with earlier Phonoclone revisions, with the anachronistic 2.5"x3.5" mounting holes. Future versions will move to the 70x90mm mounting holes to be compatible with the Sapphire and CrystalFET boards.

A small number of evaluation boards (double sided,...

Posted 19th January 2017 at 10:37 PM by rjm Comments 2
Another request.

The Sapphire4 and Unity (H) boards were based on the 47 Labs Treasure 0347 amplifier circuit, and the original was not so far away that I couldn't "de-modify" the Unity (H) board back to what is essentially a 0347.

Here's what else you need to know:

Runs off 100VA or higher power transformer, 2x15 VAC secondary, bridge rectifier, 2200 uF filtering or more on the power supply rails in addition to what is on the main boards.

The outputs go to a mute toggle switch and then a 2A fast fuse before connecting to the speaker terminals.

In the original, Q9 and Q10 are taken off board and glued to the face of Q13 and Q14 packages. This provides overtemp control, as the output transistors heat up the Vbe of Q9, 10 decreases - reducing the output bias current.

C2 was not present on the original. I include this compensation capacitor as an optional tuning option, though my own tests show it shouldn't...

Posted 18th January 2017 at 06:02 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. What more loading choices? Use two boards!

Posted 18th January 2017 at 04:33 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 a super-quick modification of the cartridge loading board I was doing anyway ... so to continue the series of 50x80mm "useful elements" boards, here is a dual bridge rectifier board for a transformer with two secondaries.

It will work with just about all of my projects, or anyplace you want to have the diodes separate from the rest of the circuit.

If there is interest I may get a set made up, or make the Gerbers available.
Recent Comments
Hi, thanks for the comment....
Posted 1st February 2017 at 12:28 AM by rjm rjm is offline
Nice to see someone...
Posted 31st January 2017 at 06:54 PM by Grasso789 Grasso789 is offline
The combination of gerb274x...
Posted 29th January 2017 at 02:10 AM by rjm rjm is offline
I tried the procedure...
Posted 24th January 2017 at 10:52 AM by Calvin Calvin is offline

Posted 19th December 2016 at 08:35 PM by rjm rjm is offline
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