Earthquaker Devices - Arrows  [traced]

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Earthquaker Devices - Arrows

Postby Bononoob » 11 May 2019, 20:02

So a buddy lent me a EQD Arrows so I traced it
Here's the Eagle Schematic and some gutshots
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287m (11 May 2019, 20:56), Intripped (11 May 2019, 20:44), karul (11 May 2019, 20:42), Manfred (11 May 2019, 20:32), modman (12 May 2019, 13:25)
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Re: Earthquaker Devices - Arrows  [traced]

Postby storyboardist » 12 May 2019, 03:00

You're really close. I traced this about a year ago, and the value off the resistor off the emitter in your schem is way too high. Should be 1.3k. And the 100k at the output goes to ground. If anyone needs a PCB I still have a few. Schem attached.

Image
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Re: Earthquaker Devices - Arrows

Postby storyboardist » 12 May 2019, 04:23

Aw heck, here's vero, perf, and etch layouts too.
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Re: Earthquaker Devices - Arrows

Postby Bononoob » 12 May 2019, 12:48

Damn how did I mess this up
Anyway thank you for the corrections and boards that's awesome

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Re: Earthquaker Devices - Arrows

Postby FeVeR2112 » 15 May 2019, 18:00

What does the R2 100R resistor do here? Seems unnecessary.
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Re: Earthquaker Devices - Arrows

Postby guiddruid » 15 May 2019, 21:14

FeVeR2112 wrote:What does the R2 100R resistor do

Limit current through D1 to ~90mA when the power is connected backwards.
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Re: Earthquaker Devices - Arrows

Postby FeVeR2112 » 19 May 2019, 23:25

guiddruid wrote:
FeVeR2112 wrote:What does the R2 100R resistor do

Limit current through D1 to ~90mA when the power is connected backwards.


Would you not just use the diode for polarity protection? A 4001 diode (1A) can handle pedal supply which are mostly 500mA at best.
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Re: Earthquaker Devices - Arrows

Postby Nocentelli » 20 May 2019, 06:30

I always understood that a ~100 ohm resistor + large electro capacitor together form a filter for the power that reduces hum.
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Re: Earthquaker Devices - Arrows

Postby guiddruid » 24 May 2019, 08:24

FeVeR2112 wrote:Would you not just use the diode for polarity protection? A 4001 diode (1A) can handle pedal supply which are mostly 500mA at best.

Without the resistor, you're relying on the power supply to gracefully limit itself - not pop a fuse, burn out a voltage regulator, or blow D1. Best practice is to assume worst case conditions, which for this protection circuit would be a very low output impedance for the PSU.
Nocentelli wrote:I always understood that a ~100 ohm resistor + large electro capacitor together form a filter for the power that reduces hum.

C4 would need to be moved to be in parallel with D1 for R2 to help with filtering noise. That would also protect C4 - the only polarised component in the design (other than the diode) - from reverse voltage.
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