BJFE - Emerald Green Distortion Machine  [traced]

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
roseblood11
Tube Twister
Information
Posts: 1862
Joined: 23 Aug 2008, 15:21
Has thanked: 344 times
Been thanked: 297 times

Post by roseblood11 »

Could be anything rated for 2 ampere, 1200 volt, maybe STTH212



I think the schematic was posted somewhere, but I can't find the link anymore...


Has anybody tried this pedal with a Proco Rat in front of it? A real Vox set to light crunch sounds great if its boosted with a rat. Could be interesting to put both circuits in one enclosure.

roseblood11
Tube Twister
Information
Posts: 1862
Joined: 23 Aug 2008, 15:21
Has thanked: 344 times
Been thanked: 297 times

Post by roseblood11 »

@ the3secondrule: Could you measure the hfe of all transistors and the leakage of the 2n1309? That would be helpful to understand the biasing...

Manfred
Transistor Tuner
Information
Posts: 1134
Joined: 05 Apr 2009, 00:42
Has thanked: 1103 times
Been thanked: 707 times

Post by Manfred »

BJF wrote:Hi,

Here you go:
http://tagboardeffects.blogspot.se/sear ... l/BJF%2FMP

And no I don't mind and never did if anyone wants to build one for their own use or a friend.

Fun note perhaps is that when doing the Bearfoot version some nice 2N1309 had been scouted for another model and I could not resist to try and liked that.
Original BJF model has same circuit but all were made with silicon metal cans medium gain drivers.

have fun
BJ
BJF Electronics
I drew separately the schematic in accord with the strip board layout.
emraldschematic.jpg

User avatar
soulsonic
Old Solderhand
Information
Posts: 3769
Joined: 27 Jun 2007, 04:38
my favorite amplifier: Stopped using amps mostly...
Completed builds: too many!
Location: Cortland, NY
Has thanked: 107 times
Been thanked: 311 times
Contact:

Post by soulsonic »

roseblood11 wrote:@ the3secondrule: Could you measure the hfe of all transistors and the leakage of the 2n1309? That would be helpful to understand the biasing...
The 2N1309 in mine had "329" marked on the side. I assume this is the Hfe.
"Analog electronics in music is dead. Analog effects pedal design is a dead art." - Fran

Manfred
Transistor Tuner
Information
Posts: 1134
Joined: 05 Apr 2009, 00:42
Has thanked: 1103 times
Been thanked: 707 times

Post by Manfred »

I'm sorry but I made a mistake on the schematic, the FET types are 2N5952.

Manfred
Transistor Tuner
Information
Posts: 1134
Joined: 05 Apr 2009, 00:42
Has thanked: 1103 times
Been thanked: 707 times

Post by Manfred »

I took closer look at the PLC shot,
and found a resistor value of 470kOhms on the gate of the second FET.

By the way, the FET stages are alike in the circutry of the Baby Pink Booster,

Manfred
Transistor Tuner
Information
Posts: 1134
Joined: 05 Apr 2009, 00:42
Has thanked: 1103 times
Been thanked: 707 times

Post by Manfred »

Better readable now.
Emerald.jpg

Manfred
Transistor Tuner
Information
Posts: 1134
Joined: 05 Apr 2009, 00:42
Has thanked: 1103 times
Been thanked: 707 times

Post by Manfred »

The LED circuitry is the same as with other BJFE pedals.
EmeraldLEDsupply.jpg
Attachments
EmeraldIndicationLED_Circuit.jpg

deep_intruder
Information
Posts: 4
Joined: 28 Apr 2012, 20:05
Has thanked: 12 times
Been thanked: 3 times

Post by deep_intruder »

In my opinion there are two mistakes, the two caps: 1u and the 4n7 of the last fet, both must be wired to the drain and not to the source!

smanq
Information
Posts: 14
Joined: 05 Sep 2007, 15:47
Has thanked: 1 time
Been thanked: 2 times

Post by smanq »

deep_intruder wrote:In my opinion there are two mistakes, the two caps: 1u and the 4n7 of the last fet, both must be wired to the drain and not to the source!
I think the 4n7 cap is right connected to the source (like on other BJF circuits), but the 1uf cap (the circuit output) must be connected to the drain.

deep_intruder
Information
Posts: 4
Joined: 28 Apr 2012, 20:05
Has thanked: 12 times
Been thanked: 3 times

Post by deep_intruder »

smanq wrote:
deep_intruder wrote:In my opinion there are two mistakes, the two caps: 1u and the 4n7 of the last fet, both must be wired to the drain and not to the source!
I think the 4n7 cap is right connected to the source (like on other BJF circuits), but the 1uf cap (the circuit output) must be connected to the drain.
I do not know how is the original, but the layout from tagboardeffects.blogspot.se is as I said.

Frank_NH
Solder Soldier
Information
Posts: 170
Joined: 12 Jun 2013, 15:18
Has thanked: 29 times
Been thanked: 75 times

Post by Frank_NH »

deep_intruder wrote:
smanq wrote:
deep_intruder wrote:In my opinion there are two mistakes, the two caps: 1u and the 4n7 of the last fet, both must be wired to the drain and not to the source!
I think the 4n7 cap is right connected to the source (like on other BJF circuits), but the 1uf cap (the circuit output) must be connected to the drain.
I do not know how is the original, but the layout from tagboardeffects.blogspot.se is as I said.
I've been following this thread and deep_intruder is correct. The vero layout has the 4.7 nF cap connected to the drain. There is already a 22 uF source resistor bypass cap at the last JFET, so I don't know if connecting the 4.7 nF cap also to the JFET source would do anything. Hence, it's probably correct going to drain, but perhaps someone could confirm that.

Manfred
Transistor Tuner
Information
Posts: 1134
Joined: 05 Apr 2009, 00:42
Has thanked: 1103 times
Been thanked: 707 times

Post by Manfred »

deep_intruder wrote:In my opinion there are two mistakes, the two caps: 1u and the 4n7 of the last fet, both must be wired to the drain and not to the source!
You are right, thanks for pointing out the mistake.
My bad. The stripboard layout is all right.

Here the corrected schematic:
EmeraldCorrected.jpg

smanq
Information
Posts: 14
Joined: 05 Sep 2007, 15:47
Has thanked: 1 time
Been thanked: 2 times

Post by smanq »

OK, the schematics reflect the board layout.
But if the A50K pot controls trebles, I confirm what I said before.
If we connect the 4n7 cap to source, when the wipe is full CW, both first and last stages have a boost on high frequencies (exactly a low cut on first stage); when the pot is full CCW last stage is around linear (4n7 has no effect on circuit) and first stage has a boost on low frequencies. It's same behavior we can see in other BJF circuits, like honey bee. So, in this way: CW=treble boost, CCW=bass boost.
If we connect the 4n7 cap to drain, when the pot is full CW we have a treble cut on last stage and a low frequencies cut on first stage (around a non sense); when the pot is full CCW last stage is around linear, the first stage has a boost on lows. This behavior for me is strange: CW=treble cut, CCW=bass boost.

Manfred
Transistor Tuner
Information
Posts: 1134
Joined: 05 Apr 2009, 00:42
Has thanked: 1103 times
Been thanked: 707 times

Post by Manfred »

smanq wrote:OK, the schematics reflect the board layout.
But if the A50K pot controls trebles, I confirm what I said before.
If we connect the 4n7 cap to source, when the wipe is full CW, both first and last stages have a boost on high frequencies (exactly a low cut on first stage); when the pot is full CCW last stage is around linear (4n7 has no effect on circuit) and first stage has a boost on low frequencies. It's same behavior we can see in other BJF circuits, like honey bee. So, in this way: CW=treble boost, CCW=bass boost.
If we connect the 4n7 cap to drain, when the pot is full CW we have a treble cut on last stage and a low frequencies cut on first stage (around a non sense); when the pot is full CCW last stage is around linear, the first stage has a boost on lows. This behavior for me is strange: CW=treble cut, CCW=bass boost.
Your explanation makes sense because there is already a treble control.
It is hard to find out the real circuitry on the pcb shots.
Is there an owner of this device who could check it out which the real circuit is?
EmeraldTwoVersions.jpg

IvIark
Tube Twister
Information
Posts: 2297
Joined: 02 Jan 2008, 00:59
Location: Manchester UK
Has thanked: 599 times
Been thanked: 608 times
Contact:

Post by IvIark »

Hi guys. The schematic was sent to me a while ago and I think at the time I was asked not to share it, but can't completely remember so here it is. If the author would prefer me not to then please let me know and i'll remove it from here.

It doesn't flow like many of us may be used to seeing schematics for these things and as such the scheme isn't as straight forward to follow at first. Q1 has the source at the top and drain at the bottom
Bearfoot-EGDM-rev2.png
"If anyone is a 'genius' for putting jacks in such a pedal in the only spot where they could physically fit, then I assume I too am a genius for correctly inserting my legs into my pants this morning." - candletears7 - TGP

User avatar
modman
a d m i n
Information
Posts: 4615
Joined: 19 Jun 2007, 17:57
Has thanked: 3476 times
Been thanked: 737 times

Post by modman »

Manfred top drawing conforms to this schematic made in 2014...look at the 4nF cap marked as
However, have a look at C14 in the old one: there is written "100k = 10pF", other schematic has this value as 100pF, don't know where that came from.
Maybe the solution the capacitor has 100k written on it, meaning 100,000 (pF) = 100nF?
C15 = 22nF or 22µF? - if you have the unit in front of you, how could you have to guess? Maybe it was traced from pictures, not from a unit.
Attachments
Re: BJFE - Emerald Green Distortion Machine component side
Re: BJFE - Emerald Green Distortion Machine component side
Re: BJFE - Emerald Green Distortion Machine trace side
Re: BJFE - Emerald Green Distortion Machine trace side
Please, support freestompboxes.org on Patreon for just 1 pcb per year! Or donate directly through PayPal

asimplesample
Information
Posts: 12
Joined: 29 Jul 2009, 18:16
Has thanked: 7 times
Been thanked: 11 times

Post by asimplesample »

I just ran across this effect today, and found this thread and the 'tagboard' layout. This thread ends with some doubts...has anyone made a final confirmation? Has anyone built one all-silicon?
Thanks!
Larry S.

User avatar
BJF
Resistor Ronker
Information
Posts: 269
Joined: 03 Nov 2007, 11:37
Has thanked: 2 times
Been thanked: 60 times

Post by BJF »

Hi There,

Oh that schematic doesn't flow well at all.
Really it's a straight forward design and as I wrote several years ago that if you'd take a BJF EGDM apart you would find three transistors

Indeed BJF version is all silicon while when I was making this for Bearfoot and seeing they had 2N1308's in stock I just went for it and really liked the sound and that is precisely what happened.

At your service
BJ

User avatar
Seiche
Old Solderhand
Information
Posts: 2590
Joined: 01 Nov 2010, 01:16
Location: Germany
Has thanked: 226 times
Been thanked: 185 times

Post by Seiche »

Manfred, the top one should be correct.

I'm working on it to verify.

Post Reply