aion PROCYON User manual

PROCYON NATURAL OVERDRIVE 1
PROJECT NAME
PROCYON
BASED ON
EFFECT TYPE
PROJECT SUMMARY
DOCUMENT VERSION
BJFe Honey Bee Overdrive
One of the original hand-made boutique pedals, originally modeled after vintage Supro amps and noted
for its dynamic low-gain tone.
Overdrive 1.0.0 (2023-11-24)
BUILD DIFFICULTY
Easy
Actual size is 2.3” x 1.86” (main board) and 1.78” x 0.87” (bypass board).

PROCYON NATURAL OVERDRIVE 2
TABLE OF CONTENTS
1Project Overview 7Drill Template
2Introduction & Usage 8Enclosure Layout
3-4 Parts List 9Wiring Diagram
5Build Notes 10 Licensing
6Schematic 10 Document Revisions
INTRODUCTION
The Procyon Natural Overdrive is a clone of the BJFe Honey Bee Overdrive, a circuit first released in
2002 that is credited for starting the “low gain overdrive” trend.
The circuit itself is a rather unique overdrive design, incorporating both soft and hard clipping and
utilizing frequency-dependent negative feedback from different points in the circuit, for a result that
is often called “amplike” in tone. It is very loosely based on the RAT, and was inspired by the sound of
overdriven Supro amps.
These pedals were handmade in Sweden and were extremely expensive ($300-400 USD), and so in 2011
an agreement was made with BearFoot FX to produce them in the USA for a more reasonable cost.
Bearfoot has also released a number of variants of this basic circuit such as the Model H, Model G,
Honey Beest, Uber Bee, and Sparkling Yellow Overdrive. While each of these circuits are similar, the
Procyon project only supports the standard Honey Bee (both BJFe and BearFoot versions, which have
minor differences).
The updated Procyon V2 has been completely overhauled from the earlier one. Based on our research of
several different Honey Bee traces, we concluded that the original FSB schematic (which all DIY Honey
Bees have been based on for nearly 15 years) was incorrect and does not represent an actual Honey
Bee. You can read more about our conclusions in our article, Revisiting the original Honey Bee FSB trace.
USAGE
The Procyon has three knobs and two toggles:
• Drive controls the gain of the op-amp stage which increases the amount of signal clipping.
• Nature is a unique tone control, doing two things at once. On one half of the rotation it affects the
amount of bass in the input stage and changes the gain ratio of the circuit. The other half depends
on the setting of the Mode switch.
• Volume controls the overall output level of the effect.
• Mode (toggle) selects between two different operations for the second half of the Nature control.
Mode I is a source bypass capacitor at Q1, which increases the amount of bass as it’s turned up.
Mode II is a variable hi-cut at the end of the circuit.
• Low (toggle) selects between three different bass modes: stock, less bass, and more bass.

PROCYON NATURAL OVERDRIVE 3
PARTS LIST
This parts list is also available in a spreadsheet format which can be imported directly into Mouser for
easy parts ordering. Mouser doesn’t carry all the parts—notably potentiometers—so the second tab lists
all the non-Mouser parts as well as sources for each.
View parts list spreadsheet →
PART VALUE TYPE NOTES
R1 360k Metal film resistor, 1/4W
R2 15k Metal film resistor, 1/4W
R3 3k Metal film resistor, 1/4W
R4 1k Metal film resistor, 1/4W
R5 1k Metal film resistor, 1/4W
R6 27k Metal film resistor, 1/4W
R7 10k Metal film resistor, 1/4W
R8 147k Metal film resistor, 1/4W
R9 1M Metal film resistor, 1/4W
R10 5k6 Metal film resistor, 1/4W
R11 2k2 Metal film resistor, 1/4W
R12 4k7 Metal film resistor, 1/4W
R14 47k Metal film resistor, 1/4W
R15 31k6 Metal film resistor, 1/4W
R16 31k6 Metal film resistor, 1/4W
R17 51R Metal film resistor, 1/4W Power supply filter resistor.
RPD 2M2 Film capacitor, 7.2 x 2.5mm Input pull-down resistor.
LEDR 10k MLCC capacitor, NP0/C0G LED current-limiting resistor. Adjust value to change LED brightness.
C1 47n Film capacitor, 7.2 x 2.5mm
C2 100pF MLCC capacitor, NP0/C0G
C3 220n Film capacitor, 7.2 x 2.5mm
C4 220n Film capacitor, 7.2 x 2.5mm
C5 220n Film capacitor, 7.2 x 2.5mm
C6 22uF Electrolytic capacitor, 5mm
C7 1uF Film capacitor, 7.2 x 3.5mm
C8 22n Film capacitor, 7.2 x 2.5mm
C9 4n7 Film capacitor, 7.2 x 2.5mm
C10 22n Film capacitor, 7.2 x 2.5mm
C11 4n7 Film capacitor, 7.2 x 2.5mm
C12 220n Film capacitor, 7.2 x 2.5mm
C13 1uF Film capacitor, 7.2 x 3.5mm
C14 4n7 Film capacitor, 7.2 x 2.5mm

PROCYON NATURAL OVERDRIVE 4
PARTS LIST, CONT.
PART VALUE TYPE NOTES
C15 4n7 Film capacitor, 7.2 x 2.5mm
C16 22uF Electrolytic capacitor, 5mm Reference voltage filter capacitor.
C17 100uF Electrolytic capacitor, 6.3mm Power supply filter capacitor.
C18 470n MLCC capacitor, X7R Power supply filter capacitor.
C19 100n MLCC capacitor, X7R Power supply filter capacitor.
D1 1N5817 Schottky diode, DO-41
D2 3mm green LED LED, 3mm, green diffused
D3 3mm green LED LED, 3mm, green diffused
D4 1N4007 Rectifier diode, DO-41
D5 1N4007 Rectifier diode, DO-41
Q1 2N5457 JFET, N-channel, TO-92 Can substitute any general-purpose JFET.
IC1 CA3130EZ Operational amplifier, DIP8
IC1-S DIP-8 socket IC socket, DIP-8
DRIVE 500kA 16mm right-angle PCB mount pot Audio (log) taper.
NATURE 50kA 16mm right-angle PCB mount pot Audio (log) taper.
VOLUME 50kB 16mm right-angle PCB mount pot Linear taper.
LOW SPDT cntr. off Toggle switch, SPDT on-off-on
MODE SPDT on-on Toggle switch, SPDT on-on
LED 5mm LED, 5mm, red diffused
IN 1/4" stereo 1/4" phone jack, closed frame Switchcraft 112BX or equivalent.
OUT 1/4" mono 1/4" phone jack, closed frame Switchcraft 111X or equivalent.
DC 2.1mm DC jack, 2.1mm panel mount Mouser 163-4302-E or equivalent.
FSW 3PDT Stomp switch, 3PDT
BATT. 9V 9V battery snap Soft vinyl type. The hard-shell type will not fit.
ENC 125B Enclosure, die-cast aluminum Can also use a Hammond 1590N1.

PROCYON NATURAL OVERDRIVE 5
BUILD NOTES
Variants
We compared several versions of the HBOD for the Procyon V2 and found that many of the components
had different values across the versions. Here are the circuits we referenced:
• Original BJFe (2 units from FSB trace)
• Bearfoot
• Moody Sounds DIY kit (designed in conjunction with BJFe)
• One Control
• BJFe Blueberry Bass Overdrive
Aside from the Blueberry, the changes are too numerous to list here, so we annotated the schematic
instead, which can be found on the next page.
We put the two biggest changes (the bass frequency capacitor and the operation of the Nature switch)
on toggle switches. The other changes are for the most part inconsequential.
The default parts list is for the original BJFe Honey Bee.
To read more on this process, check out our post: Revisiting the original Honey Bee FSB trace
Blueberry part substitutions
To build the Blueberry Bass Overdrive, make the following substitutions from the default list:
• R12: 4k7 →2k
• R14: 47k →27k
• R15: 31.6k →47k
• R16: 32.6k →47k
• C1: 47n →22n
• C11: 4n7 →47n
• C12: 220n →22n
• C14: omit (4n7 in original)
• C15: 4n7 →2n2
• D2-3: 3mm green LED →3mm red LED

SCHEMATIC
PROCYON NATURAL OVERDRIVE 6
C12:
Unknown in original BJFe version (the main
unit traced did not have this capacitor, using
the other mode instead)
22n in BJF kit version
220n in Bearfoot and One Control
1N4007
R12:
Unknown in original BJFe version (the main
unit traced did not have this resistor, using
the other mode instead)
5k1 in BJF kit version
4k7 in Bearfoot and One Control
R8 sometimes 150k
Blueberry:
R12 2k
R14 27k
R15 47k
R16 47k
C1 22n
C11 47n
C12 22n
C14 omit
C15 2n2
D2-3 3mm red
R2 sometimes 14.7k
R3:
3k in FSB trace and Bearfoot
3.6k in BJF kit and One Control version
(3k gives slightly more clean at the
very bottom of the range)
LOW switch:
220n bottom (stock)
110n middle (less bass)
330n top (more bass)
MODE switch:
I is a variable bass boost (Q1 source bypass)
I
II is variable hi-cut at the end of the circuit
II
R15, R16:
31.6k in original HBOD
47k in BJF kit version, One Control,
and Blueberry
R17 47R in BJFe kit version
R11:
2.2k in original BJFe
2.7k in BJFe kit version
2.6k in One Control version
2.61k in Bearfoot version
2.2k recommended for more output volume
(may need to be adjusted based on JFET used)
C11:
22n in Bearfoot version
47n in One Control version
and Blueberry
Nature 500kA in some units
(likely a mistake in production)
C6 sometimes 2.2uF
IN
OUT
GND
2M2
1N5817
100uF
GND
+9V
100n
VA
51R
500kA
50kB
31k6
31k6
22uF
GND GND
50kA
47n
360k
15k
CA3130EZ
GND
100pF
3k
3mm green
3mm green
1k
220n
220n
GND
1k
1uF
22n
27k
10k
4n7
147k
22n
4n7
1M
2k2
GND
GND
GND
GND
5k6
1uF
47k
4n7
GND
4k7
2N5457
VA
VA
22uF
VB
VB
4n7
GND
220n
220n
GND
470n
GNDGND
RPD
D1
C17
C19
R17
1
2
3
DRIVE
VOLUME
1
2
3
R15
R16
C16
NATURE
1
2
3
C1
R1
R2 5
1
2
3
6
8
74
IC1
C2
R3
D2
D3
R4
C3
C12
R5
C7
C8
R6
R7
C9
R8
C10
C11
R9
R11
D4 D5
R10
C13
R14
C14
R12
Q1
C6
C15
2
3
1
MODE
C5
2
3 1
LOW
C4
C18

PROCYON NATURAL OVERDRIVE 7
DRILL TEMPLATE
Cut out this drill template, fold the edges and tape it to the enclosure. Before drilling, it’s recommended
to first use a center punch for each of the holes to help guide the drill bit.
Ensure that this template is printed at 100% or “Actual Size”. You can double-check this by measuring
the scale on the printed page.
Top jack layout assumes the use of closed-frame jacks like the Switchcraft 111X. If you’d rather use
open-frame jacks, please refer to the Open-Frame Jack Drill Template for the top side.
LED hole drill size assumes the use of a 5mm LED bezel, available from several parts suppliers. Adjust
size accordingly if using something different, such as a 3mm bezel, a plastic bezel, or just a plain LED.
x: -0.65, y: +1.71 x: 0.65, y: +1.71
ø9/32” ø9/32”
x: -0.85, y: +0.66
ø1/4”
x: 0, y: +0.66
ø9/32”
x: 0, y: -1.20
ø15/32”
x: -0.775, y: -1.20
ø5/16”
CENTER (0,0)
ø3/8” ø1/2”
0.385”
0.625” 0.625”
ø3/8”
OUT DC IN
125B
VOLUME
MODE LOWNATURE
DRIVE
FOOTSWITCHLED
x: +0.85, y: +0.66
ø1/4”
0 1 2
CM
0 1
INCH

PROCYON NATURAL OVERDRIVE 8
ENCLOSURE LAYOUT
Enclosure is shown without jacks. See next page for jack layout and wiring.
125B

PROCYON NATURAL OVERDRIVE 9
WIRING DIAGRAM
125B
IN +VGND N.C. N.C. OUT
PCB
IN
GND +V +V JACK GND JACK
OUTIN
GND GND PCB
OUT
Shown with optional 9V battery. If battery is omitted, both jacks can be mono rather than one being stereo.
Leave the far-right lug of the DC jack unconnected.

PROCYON NATURAL OVERDRIVE 10
LICENSE & USAGE
No direct support is offered for these projects beyond the provided documentation. It’s assumed
that you have at least some experience building pedals before starting one of these. Replacements and
refunds cannotbe offered unless it can be shown that the circuit or documentation are in error.
All of these circuits have been tested in good faith in their base configurations. However, not all the
modifications or variations have necessarily been tested. These are offered only as suggestions based
on the experience and opinions of others.
Projects may be used for commercial endeavors in any quantity unless specifically noted. No
attribution is necessary, though a link back is always greatly appreciated. The only usage restrictions
are that (1) you cannot resell the PCB as part of a kit without prior arrangement, and (2) you cannot
“goop” the circuit, scratch off the screenprint, or otherwise obfuscate the circuit to disguise its source.
(In other words: you don’t have to go out of your way to advertise the fact that you use these PCBs, but
please don’t go out of your way to hide it. The guitar effects industry needs more transparency, not less!)
DOCUMENT REVISIONS
2.0.0 (2023-11-24)
Complete overhaul based on new research. Added toggle switches inspired by the One Control version.
1.0.1 (2021-11-23)
Corrected R8 to 147k based on likely inaccurate FSB trace dating back more than 10 years. The
previous version of the build doc showed 47k.
1.0.0 (2018-08-22)
Initial release.