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Jennings Electronic Industries (JEI) - Phaser

PostPosted: 09 Jul 2015, 08:39
by Bernardduur
Yesterday this pedal came in the mail. I was fascinated by the origin (from the hands of the AC30 designers) but also wanted to hear it in action.

Fired up the unit has a HUGE volume boost with the phaser engaged or in bypass mode. It is not true bypass I suppose. The phaser has no LFO and can be used by rocking the pedal forwards and backwards. It can be activated the same way as a crybaby wah.

The sound is surprisingly nice. A very complex phaser sound that I was not expecting from it. Looking at the circuit it only has transistors, no IC can be found. (if I recall, I've never seen a pure transistor based phaser).

More pics will follow; I'll trace it when I got some spare time!
$_57.JPG


http://www.hendrixguitars.com/Ef230.htm

http://www.effectsdatabase.com/model/je

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 09 Jul 2015, 12:14
by Fender3D
The very first issue of Elektor in Italy, back in the late '70-early '80, featured a phaser circuit, it had two 1-transistor-phase stages (outputs on E and C) ala ***vibe, a dual gang pot instead of LDRs, I'm sorry but I don't recall what the input and input stages were...

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 09 Jul 2015, 12:18
by Bernardduur
Oops, forgot the univibe :)

That one is a pure transistor phaser

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 10 Jul 2015, 07:19
by Bernardduur
DSCF6084.jpg
DSCF6093.jpg
DSCF6097.jpg

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 10 Jul 2015, 07:21
by Bernardduur
DSCF6098.jpg
DSCF6099.jpg
DSCF6100.jpg

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 10 Jul 2015, 07:25
by Bernardduur
And the schematic!!

JEI - Phaser.JPG

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 10 Jul 2015, 12:50
by tube-exorcist
The original circuit can be found in Practical Electronics October 1973. The potentiometer should be alogarithmic type.

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 12 Jul 2015, 15:39
by Bernardduur
tube-exorcist wrote:The original circuit can be found in Practical Electronics October 1973. The potentiometer should be alogarithmic type.


Nice! I can't find that issue online; would you have one? I'm interested in the article....

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 12 Jul 2015, 16:17
by tube-exorcist
Bernardduur wrote:
tube-exorcist wrote:The original circuit can be found in Practical Electronics October 1973. The potentiometer should be alogarithmic type.


Nice! I can't find that issue online; would you have one? I'm interested in the article....


Sorry, but I donĀ“t have an original one - I found the article on Mar 24, 2001.... ONLINE. And yes, it is still there waiting for interested ones:

http://www.synthdiy.com/show/?id=1118

(Download link at the the right bottom "pha.pdf".)

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 12 Jul 2015, 18:37
by Manfred
Hi Bernardduur,

thanks for dissectioning, great!
How is the size of the PCB?
Do you made a shot of the component side of the PCB too,
there are some components hidden by the plug sockets on the device shot?
I intend to create a replica PCB.

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 12 Jul 2015, 19:13
by Fender3D
lol
:mrgreen:

looking at the several magazines publishing(ed) this...
it may be a good argument for the "The Big Catfight: ethics/cloning/copying/stealing/personal" thread... :horsey:

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 12 Jul 2015, 23:13
by Manfred
Fender3D wrote:lol
:mrgreen:

looking at the several magazines publishing(ed) this...
it may be a good argument for the "The Big Catfight: ethics/cloning/copying/stealing/personal" thread... :horsey:


I guess there is no argument, because it is a discontinued product since more than 40 years. 8)
Of course for noncommercial use only. :wink:

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 13 Jul 2015, 21:03
by Bernardduur
@ tube exorcist: Thanks for the link!!

@ Manfred: here ya go

DSCF6099.jpg


Size: 7cm x 5.5cm

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 13 Jul 2015, 21:51
by Manfred
Hi Bernardduur,

thanks for the shot and the board size.

Re: Jennings Electronic Industries (JEI) - Phaser

PostPosted: 04 Jan 2017, 00:03
by Manfred
I create the PCB layout clone according to the the shots.

JEI3Layout.JPG


JEI3_PCB.jpg