Dunlop - Eric Johnson Signature Fuzz Face EJF1  [traced]

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Post by Nocentelli »

Mouseydung wrote:...if BC183s are supposed to have different C-B-E pin configurations (as mine certainly do), wouldn't that make the schematics here (including those posed by Zokk and bedotman on May 19, 2012) incorrect?
Not really: There are only five resistors in the whole circuit, and only one way to arrange them to make a fuzzface that will actually work. E.g. the largest (121k) must be the feedback resistor, it cannot be used in any other position and the circuit still work. The values of the resistors are pretty close to the "original" fuzzface values (as you can see from The Lemon's schematic). Other clues are derived from the transistor connections: One pin of one transistor is grounded - it must therefore be Q1's emitter: The same transistor has one pin directly connected to Q2 - This must be Q1's collector, and it is connected to Q2's base. The pin on Q2 that is connected to the fuzz pot must be the emitter, so the other one must be the collector.
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Post by DrNomis »

Mouseydung wrote:This is probably a stupid question, but here goes: :oops:

At the top of page 18 of this thread, there is a schematic posted by TheLemon, dated Oct 3, 2012. Right below it is a closeup pic of the BC183 transistors. Am I correct to assume that all the schematics posted here were traced from the front/back sides of the PCBs of the same one or two EJ fuzzes volunteered as samples? If so, and if BC183s are supposed to have different C-B-E pin configurations (as mine certainly do), wouldn't that make the schematics here (including those posed by Zokk and bedotman on May 19, 2012) incorrect?


Not really since the pinouts for the transistors wouldn't have much effect on how the other components are connected up, the only difference is that the copper foil tracks on the underside of the circuit board would be routed differently to accomodate the different C-B-E pin configurations, but it would still be the same circuit and would function in exactly the same way, so therefore you'd be pretty safe in assuming that all the schematics posted in this thread are correct although there may be some minor component value differences........ :thumbsup
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Post by Nocentelli »

Just to be clear - The schematics posted can be assumed to be correct since the emitter, base and collector of both trannies is clearly shown by the symbol orientation, i.e. For npn transistors, the emitter has an arrow pointing to ground, base is perpendicular to a vertical bar line, collector is the other one; However, any component layout (pcb/vero/perf/point-to-point) you find for any circuit *may* be correct for your particular pinout, but may not. Layouts do not always clearly state the pinout, and may just show an outline of the transistor, in which case you cannot always guarantee the outline is oriented the right way for every transistor.

For some reason BC183s seem to have a bewildering variety or pinouts, I remember one of my first few builds was a D*A*M meathead that had a 183L or C or something, I found several contradictory spec sheets (CBE, BCE and EBC) and gave up before I got it working.
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Post by Mouseydung »

Nocentelli wrote: Not really: There are only five resistors in the whole circuit, and only one way to arrange them to make a fuzzface that will actually work. E.g. the largest (121k) must be the feedback resistor, it cannot be used in any other position and the circuit still work. The values of the resistors are pretty close to the "original" fuzzface values (as you can see from The Lemon's schematic). Other clues are derived from the transistor connections: One pin of one transistor is grounded - it must therefore be Q1's emitter: The same transistor has one pin directly connected to Q2 - This must be Q1's collector, and it is connected to Q2's base. The pin on Q2 that is connected to the fuzz pot must be the emitter, so the other one must be the collector.
DrNomis wrote: Not really since the pinouts for the transistors wouldn't have much effect on how the other components are connected up, the only difference is that the copper foil tracks on the underside of the circuit board would be routed differently to accomodate the different C-B-E pin configurations, but it would still be the same circuit and would function in exactly the same way, so therefore you'd be pretty safe in assuming that all the schematics posted in this thread are correct although there may be some minor component value differences........ :thumbsup
Okay, well then I know I'm on the right track. Phew! :P
I had already figured everything you guys explained above, by comparing the circuit with other fuzz circuits, etc. :-p Although, I did find that the copper tracks on the EJ fuzz are somewhat different from a standard Dallas Arbiter. So just to be sure of things, I did my own schematic by tracing the front and beck-end PCB pics posted here. It all seemed to add up, apart from the pinout factor. I was just having trouble reconciling it with the fact (as I understood it prior to your replies) that BC183s were supposed to come as BCEs.
Nocentelli wrote:Just to be clear - The schematics posted can be assumed to be correct since the emitter, base and collector of both trannies is clearly shown by the symbol orientation, i.e. For npn transistors, the emitter has an arrow pointing to ground, base is perpendicular to a vertical bar line, collector is the other one; However, any component layout (pcb/vero/perf/point-to-point) you find for any circuit *may* be correct for your particular pinout, but may not. Layouts do not always clearly state the pinout, and may just show an outline of the transistor, in which case you cannot always guarantee the outline is oriented the right way for every transistor.
For some reason BC183s seem to have a bewildering variety or pinouts, I remember one of my first few builds was a D*A*M meathead that had a 183L or C or something, I found several contradictory spec sheets (CBE, BCE and EBC) and gave up before I got it working.
The answer is right there. All of the datasheets I found for BC183s, including the one that the seller sent along with my small batch of BC183Ls, specify the C-B-E configuration. However, this proved to be incorrect, as mine were clearly B-C-E and I had to twist the legs around to get them to work.
:oops: So in the end, maybe this was a stupid question. I should've just asked if BC183s also come with C-B-E pinouts, as would clearly have to be the case, based on the circuits generated from the pics of the innards of the two sample EJ fuzzes on this thread.

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Post by DrNomis »

Mouseydung wrote:
Nocentelli wrote: Not really: There are only five resistors in the whole circuit, and only one way to arrange them to make a fuzzface that will actually work. E.g. the largest (121k) must be the feedback resistor, it cannot be used in any other position and the circuit still work. The values of the resistors are pretty close to the "original" fuzzface values (as you can see from The Lemon's schematic). Other clues are derived from the transistor connections: One pin of one transistor is grounded - it must therefore be Q1's emitter: The same transistor has one pin directly connected to Q2 - This must be Q1's collector, and it is connected to Q2's base. The pin on Q2 that is connected to the fuzz pot must be the emitter, so the other one must be the collector.
DrNomis wrote: Not really since the pinouts for the transistors wouldn't have much effect on how the other components are connected up, the only difference is that the copper foil tracks on the underside of the circuit board would be routed differently to accomodate the different C-B-E pin configurations, but it would still be the same circuit and would function in exactly the same way, so therefore you'd be pretty safe in assuming that all the schematics posted in this thread are correct although there may be some minor component value differences........ :thumbsup
Okay, well then I know I'm on the right track. Phew! :P
I had already figured everything you guys explained above, by comparing the circuit with other fuzz circuits, etc. :-p Although, I did find that the copper tracks on the EJ fuzz are somewhat different from a standard Dallas Arbiter. So just to be sure of things, I did my own schematic by tracing the front and beck-end PCB pics posted here. It all seemed to add up, apart from the pinout factor. I was just having trouble reconciling it with the fact (as I understood it prior to your replies) that BC183s were supposed to come as BCEs.
Nocentelli wrote:Just to be clear - The schematics posted can be assumed to be correct since the emitter, base and collector of both trannies is clearly shown by the symbol orientation, i.e. For npn transistors, the emitter has an arrow pointing to ground, base is perpendicular to a vertical bar line, collector is the other one; However, any component layout (pcb/vero/perf/point-to-point) you find for any circuit *may* be correct for your particular pinout, but may not. Layouts do not always clearly state the pinout, and may just show an outline of the transistor, in which case you cannot always guarantee the outline is oriented the right way for every transistor.
For some reason BC183s seem to have a bewildering variety or pinouts, I remember one of my first few builds was a D*A*M meathead that had a 183L or C or something, I found several contradictory spec sheets (CBE, BCE and EBC) and gave up before I got it working.
The answer is right there. All of the datasheets I found for BC183s, including the one that the seller sent along with my small batch of BC183Ls, specify the C-B-E configuration. However, this proved to be incorrect, as mine were clearly B-C-E and I had to twist the legs around to get them to work.
:oops: So in the end, maybe this was a stupid question. I should've just asked if BC183s also come with C-B-E pinouts, as would clearly have to be the case, based on the circuits generated from the pics of the innards of the two sample EJ fuzzes on this thread.


I'm starting to think that there were a few companys that manufactured their own version of BC183 Silicon Transistors, I'm guessing that this would account for the differing pinouts, best thing to do is test them before you solder them in....... :thumbsup
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Post by mmolteratx »

http://www.peakelec.co.uk/acatalog/jz_dca55.html

Is the shit for finding the pinouts/other characteristics of random transistors.

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Post by Mouseydung »

mmolteratx wrote:http://www.peakelec.co.uk/acatalog/jz_dca55.html
Is the shit for finding the pinouts/other characteristics of random transistors.
It's a shame the device doesn't come with any standard sockets, or I would've ordered one. If say, you had to test a batch of 500 transistors, it would be a pain to have to attach and detach the three alligator grips to the tiny little components each and every time :? My DMM comes with a socket for testing PNP and NPN transistors with common pinouts, but it doesn't allow for any unusual configurations, which could easily have been done if they'd supplied a socket that goes C-B-E-C-B. That way, all pins with all possible configurations (CBE/EBC; CEB/BEC; BCE/ECB) could easily be plugged in and removed.

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Post by electrip »

Mouseydung wrote:
mmolteratx wrote:http://www.peakelec.co.uk/acatalog/jz_dca55.html
Is the shit for finding the pinouts/other characteristics of random transistors.
It's a shame the device doesn't come with any standard sockets, or I would've ordered one. If say, you had to test a batch of 500 transistors, it would be a pain to have to attach and detach the three alligator grips to the tiny little components each and every time :? My DMM comes with a socket for testing PNP and NPN transistors with common pinouts, but it doesn't allow for any unusual configurations, which could easily have been done if they'd supplied a socket that goes C-B-E-C-B. That way, all pins with all possible configurations (CBE/EBC; CEB/BEC; BCE/ECB) could easily be plugged in and removed.
You will not test a batch of 500 identical bjts with any tester neither with grips nor with a socket.
Putting long legs of old transistors in a socket is just as fiddly as using the test clips.
Measurement time is way to long for using on a greater number of parts.
For big batches of germaniums I would use the R.G.-method to presort to different bins of leakage
and then for HFE.

I use a sort of socket (connector in a small bench vice) with the grips connected to the lugs.
I am still looking for a connector or socket for TO-92 leads spaced 0.05" (1.27 mm).

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Post by Mouseydung »

electrip wrote: You will not test a batch of 500 identical bjts with any tester neither with grips nor with a socket.
I might just be crazy enough to do it. In my pedantic and failed attempt to capture the sound of the EJ FF, I did manually sort through about 150 BC547/8/9 transistors by plugging them into the socket that came with my DMM to test the hFE values and label each transistor. That was "easy" enough, but I also had a batch of miscellaneous unidentified transistors with unknown pin configurations, which was a bit more time consuming to sort through. :blackeye
electrip wrote: For big batches of germaniums I would use the R.G.-method to presort to different bins of leakage and then for HFE.
Hmmm... I'll have to look into that method...
electrip wrote: I use a sort of socket (connector in a small bench vice) with the grips connected to the lugs.
I am still looking for a connector or socket for TO-92 leads spaced 0.05" (1.27 mm).
Now that's a sensible way to do it! Why didn't I think of that? :slap:
I'll try to set up something similar in future to deal with the unusual pin configurations that can come with BC183s.

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Post by mmolteratx »

Mouseydung wrote:
mmolteratx wrote:http://www.peakelec.co.uk/acatalog/jz_dca55.html
Is the shit for finding the pinouts/other characteristics of random transistors.
It's a shame the device doesn't come with any standard sockets, or I would've ordered one. If say, you had to test a batch of 500 transistors, it would be a pain to have to attach and detach the three alligator grips to the tiny little components each and every time :? My DMM comes with a socket for testing PNP and NPN transistors with common pinouts, but it doesn't allow for any unusual configurations, which could easily have been done if they'd supplied a socket that goes C-B-E-C-B. That way, all pins with all possible configurations (CBE/EBC; CEB/BEC; BCE/ECB) could easily be plugged in and removed.
I actually sorted through about 4000 germaniums with it. Took forever, but meh. I had nothing else to do that weekend anyways. :lol:

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Post by Chris Brown »

I use the rg method (gospel box) with 9v regulated... Sockets mounted and also clips hanging so whatever is easiest...

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Post by DrNomis »

I either use my Digital Multimeter set to the Transistor Hfe function, or my Semiconductor Analyser to check the pinouts of Transistors, works for me.... :thumbsup
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Post by Mouseydung »

I'm waiting for a new batch of BC183s to arrive. Hopefully the hFEs will come close to the magical numbers of 217 and 547, and the voltages on each pin will all miraculously align themselves to those of an original EJ fuzz :block:

For now, with the current BC183Ls in my build (in the 480-520 hFE range) there are some issues I'm wondering about. I don't have an original EJ FF with which to compare, so I have no idea if my build is working as it should. I've built a couple of other silicone/germanium fuzzes before and owned several others in the past, but none of them fizzle out when I turn the fuzz knob down. With my current build, the fuzz begins sputtering and gating with the knob at about 70% and at 50% or lower, it's like an off switch -- there is no sound whatsoever.

Is it supposed to behave this way, or is my circuit off balance somewhere? :scratch:

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Post by Chris Brown »

Mouseydung wrote:I'm waiting for a new batch of BC183s to arrive. Hopefully the hFEs will come close to the magical numbers of 217 and 547, and the voltages on each pin will all miraculously align themselves to those of an original EJ fuzz :block:

For now, with the current BC183Ls in my build (in the 480-520 hFE range) there are some issues I'm wondering about. I don't have an original EJ FF with which to compare, so I have no idea if my build is working as it should. I've built a couple of other silicone/germanium fuzzes before and owned several others in the past, but none of them fizzle out when I turn the fuzz knob down. With my current build, the fuzz begins sputtering and gating with the knob at about 70% and at 50% or lower, it's like an off switch -- there is no sound whatsoever.

Is it supposed to behave this way, or is my circuit off balance somewhere? :scratch:
Put a trimmer on both collectors and dial the voltage of q1c between 1.2-1.5 and q2c between 3-3.5

This circuit with the weak bias does come a lot closer to gating than other well built fuzzes but that's also what gives it "the sound". Run the fuzz at 95-100% and then roll off the guitar's volume/tone knobs... I like strat neck with volume on 7-8 and tone full up (also good for the 2 and 4 setting). Also, strat bridge with the volume full up and the tone rolled back to 6-7 is how Eric Johnson gets his lead tone... There's a video somewhere where he discusses it.

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Post by DrNomis »

I noticed a couple of things while playing around with Q2's bias setting and swapping transistors, when I adjusted the biasing of Q2 so that it had about 3.17V on it's collector I got something that sounded close to the EJ Fuzz Face but there wasn't much sustain and the output level was a bit low, it didn't matter what Hfes I had for the two transistors, I actually found it very hard to dial in the sound, so I might just go ahead and bite the bullet and order myself a proper factory-made Jim Dunlop EJ fuzz Face soon....... :thumbsup
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DrNomis wrote:I noticed a couple of things while playing around with Q2's bias setting and swapping transistors, when I adjusted the biasing of Q2 so that it had about 3.17V on it's collector I got something that sounded close to the EJ Fuzz Face but there wasn't much sustain and the output level was a bit low, it didn't matter what Hfes I had for the two transistors, I actually found it very hard to dial in the sound, so I might just go ahead and bite the bullet and order myself a proper factory-made Jim Dunlop EJ fuzz Face soon....... :thumbsup
Don't discount q1 bias... it plays a big role in the sound of this circuit.

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Post by Chris Brown »

Also early on we figured out that 330E is too low for most of us... I ended up with somewhere around 500... other people went as high as 680 I believe.

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Post by DrNomis »

Chris Brown wrote:Also early on we figured out that 330E is too low for most of us... I ended up with somewhere around 500... other people went as high as 680 I believe.

I've got my Q1 collector resistor at 47k and I think I was getting about 1.30V on Q1's collector with 3.17V on Q2's collector, so it looks like I need to increase it, maybe to 56k?....... :hmmm:


Q1 is a BC557B with Hfe 340, q2 is a BC559 with Hfe 620.... :thumbsup


Going to have to do some breadboarding of the EJ Fuzz Face circuit but substitute two trinmpots for the two collector resistors, and see what resistance values I come up with...... :hmmm:
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Post by Mouseydung »

Chris Brown wrote:Also early on we figured out that 330E is too low for most of us... I ended up with somewhere around 500... other people went as high as 680 I believe.
What is this "330E" you're referring to? I've done a search and couldn't find anything.

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Post by Mouseydung »

DrNomis wrote:I noticed a couple of things while playing around with Q2's bias setting and swapping transistors, when I adjusted the biasing of Q2 so that it had about 3.17V on it's collector I got something that sounded close to the EJ Fuzz Face but there wasn't much sustain and the output level was a bit low, it didn't matter what Hfes I had for the two transistors, I actually found it very hard to dial in the sound, so I might just go ahead and bite the bullet and order myself a proper factory-made Jim Dunlop EJ fuzz Face soon....... :thumbsup
DrNomis wrote:Q1 is a BC557B with Hfe 340, q2 is a BC559 with Hfe 620.... :thumbsup
I discovered it a fundamentally different sound and fuzz behavior from using BC183Ls instead of BC547s, BC548s and BC549s, despite the hFE values of the latter being theoretically close to those of the original EJ fuzz presented here, and despite their being listed as potential replacements for BC183s. Maybe there's just something special about these BC183s. Among others, fuzz pedal makers like Analog Man have attested to this.

My current BC183s aren't really right for this project, so I'm waiting for the delivery of some new batches (darn, I wrote "bitches" by accident! :hmmm: ), hopefully sometime this coming week.
:horsey:

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