Search found 82 matches

by guiddruid
15 Jul 2020, 08:57
Forum: Boutique Stompboxes dissected...
Topic: Amptweaker - Side Track Bypass Loop [traced]
Replies: 2
Views: 1209

Re: Amptweaker - Side Track Bypass Loop [traced]

If the 3PDT were used to switch the supply to the anode side of the LEDs, and the bypass loop LED's cathode were connected to the ring terminal of the send or receive jacks, then the bypass LED would only light if the bypass loop is connected.
by guiddruid
18 Nov 2019, 20:58
Forum: Boutique Stompboxes dissected...
Topic: Pete Cornish - OC-1 Optical Compressor [traced]
Replies: 13
Views: 5507

Re: Pete Cornish - OC-1 Optical Compressor [traced]

But the only way to forward-bias D2 is for pin 6 to go below GND. Even if that were possible, with the supply rails on IC3 being +Vc/GND, I don't see how the input circuitry in the opamp can work.
by guiddruid
16 Nov 2019, 10:03
Forum: Boutique Stompboxes dissected...
Topic: Pete Cornish - OC-1 Optical Compressor [traced]
Replies: 13
Views: 5507

Re: Pete Cornish - OC-1 Optical Compressor [traced]

IC3A/IC3B looks like the "precision full wave rectifier" circuit from Horowitz & Hill (don't have my copy to hand, but IIRC this is it; https://en.wikipedia.org/wiki/Precision_rectifier), but with D2 connected on a separate op-amp. Seems to me this should be functionally equivalent. Not sure what (i...
by guiddruid
26 Jul 2019, 19:52
Forum: Boutique Stompboxes dissected...
Topic: Fortin Zuul [traced]
Replies: 42
Views: 10262

Re: Fortin Zuul [traced]

The "gate" is not on/off. As the level of the key signal reduces, the input->output gain reduces more quickly. For example, key halves in amplitude results in gain dropping by 4. (not actual numbers, just for example). If you turn the control knob up you should hear the "bleed through" get quieter &...
by guiddruid
24 May 2019, 07:24
Forum: Boutique Stompboxes dissected...
Topic: Earthquaker Devices - Arrows [traced]
Replies: 10
Views: 2827

Re: Earthquaker Devices - Arrows [traced]

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 ass...
by guiddruid
15 May 2019, 20:14
Forum: Boutique Stompboxes dissected...
Topic: Earthquaker Devices - Arrows [traced]
Replies: 10
Views: 2827

Re: Earthquaker Devices - Arrows [traced]

FeVeR2112 wrote:What does the R2 100R resistor do
Limit current through D1 to ~90mA when the power is connected backwards.
by guiddruid
13 May 2019, 20:13
Forum: Boutique Stompboxes dissected...
Topic: Fortin Zuul [traced]
Replies: 42
Views: 10262

Re: Fortin Zuul [traced]

Not connecting the ground makes sense. The key input on the Zuul does have a ground connection though. Something like this might be a better approach to producing a buffered key pass-through; https://www.ti.com/lit/an/sloa143/sloa143.pdf Then again, perhaps just making the key input really high impe...
by guiddruid
13 May 2019, 07:32
Forum: Boutique Stompboxes dissected...
Topic: Fortin Zuul [traced]
Replies: 42
Views: 10262

Re: Fortin Zuul [traced]

Try turning the gate control to minimum & playing softly with the pedal on - I suspect you'll hear the buzz then too, which is caused by a ground loop. Because the key input is not isolated, you're connecting the ground at very different points in your signal chain together, which can cause the prob...
by guiddruid
06 May 2019, 16:39
Forum: Boutique Stompboxes dissected...
Topic: Fortin Zuul [traced]
Replies: 42
Views: 10262

Re: Fortin Zuul [traced]

C7/R7/C8 - 99% this is just a cut & paste mistake when adding an emitter-follower input buffer to the Marshall circuit J0K3RX linked to. The resistor between the two capacitors is functionally equivalent to what Manfred drew - order doesn't make any difference. Other than polarised caps (not the cas...
by guiddruid
24 Feb 2019, 15:53
Forum: Boutique Stompboxes dissected...
Topic: Fortin Zuul [traced]
Replies: 42
Views: 10262

Re: Fortin Zuul [traced]

Guts; https://imgur.com/a/GSyJqGp The 3 ICs match this similar device - https://www.pedalpcb.com/product/muzzle/ Could do with ground loop isolation on the key input. I have the key input connected via a Suhr buffer, otherwise I get buzzing with the Zuul connected in the effects loop of my Hotone He...
by guiddruid
10 Sep 2018, 19:54
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Boss - SD-1w Super OverDrive (Waza Craft)
Replies: 6
Views: 2393

Re: Boss SD-1w Super OverDrive (Waza Craft)

Found a good reference for SMD markings; http://caxapa.ru/thumbs/588912/smd-codes.pdf Have some promising candidates for some of the mystery 3 pin devices. JY , SOT23 N channel JFET in switching circuit 2SK208, IDSS classification 1.2 to 3.0 mA g [-+-] [+-+] s d DG , NPN transistor of some kind, bis...
by guiddruid
10 Sep 2018, 06:33
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Boss - SD-1w Super OverDrive (Waza Craft)
Replies: 6
Views: 2393

Re: Boss SD-1w Super OverDrive (Waza Craft)

Thanks dv8r601 - that doesn't make sense, given where they are in the circuit though. The NXP datasheet for BA199 also says the markings would be "JYp", "JYt" or "JYW", and that's not the case here.
by guiddruid
09 Sep 2018, 12:47
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Boss - SD-1w Super OverDrive (Waza Craft)
Replies: 6
Views: 2393

Re: Boss SD-1w Super OverDrive (Waza Craft)

There are indeed no opamps in the circuit, unlike the original SD1 - the 8 pin ICs are switches (see below). Opamps look to have been replaced with discrete transistor circuits. The drive and tone stages are not identical. Input + drive stage is Q2(XG), Q18(DG), Q3(DG), Q4(JY), Q5(XG), Q6(XG) Q4(JY)...
by guiddruid
08 Sep 2018, 13:19
Forum: Modern Stompbox Effects (1975 - ...)
Topic: Boss - SD-1w Super OverDrive (Waza Craft)
Replies: 6
Views: 2393

Boss - SD-1w Super OverDrive (Waza Craft)

Gut shots - https://imgur.com/a/UPaObOE Not the best photos, sorry - cables get in the way. Really needs all the wires to be de-soldered to get a proper look at it. Input is top-right of the circuit (W1 & W2), then heads down the right-hand-side, across & back up the left-hand-side. Looks like there...
by guiddruid
07 Apr 2018, 20:03
Forum: Parts Sourcing & Trading
Topic: LDR for Morley wah
Replies: 0
Views: 2038

LDR for Morley wah

Morley PSW Pro Series Wah schematic calls for an LDR with 150-250 ohm LUX resistance. These do not seem to be very easy to source, other than as Morley M79-211564-000 spare part from various places. Far too much time wasted trawling the web has turned up what looks like a suitable alternative (or po...
by guiddruid
21 Feb 2011, 14:28
Forum: Boutique Stompboxes dissected...
Topic: OKKO Dominator [traced]
Replies: 151
Views: 53219

Re: OKKO Dominator [schematic, layout] [traced]

Standard linear regulators have a dropout voltage (=minimum value of vout-vin) that's around 1.7 at full load - it's a little less at lower output currents, but still over a volt. The charge pump will output at most (0ma load) 2*(9V - diode drop). With magic diodes and no load you would be at 18v. T...
by guiddruid
20 Feb 2011, 17:02
Forum: Boutique Stompboxes dissected...
Topic: OKKO Dominator [traced]
Replies: 151
Views: 53219

Re: OKKO Dominator [schematic, layout] [traced]

Probably better going the other end of R38 - I assume that resistor is there to affect the distortion stage.
by guiddruid
20 Feb 2011, 11:02
Forum: Boutique Stompboxes dissected...
Topic: OKKO Dominator [traced]
Replies: 151
Views: 53219

Re: OKKO Dominator [schematic, layout] [traced]

It seems completely pointless to run some of the opamps off the unregulated supply anyway. I would be suprised if it were possible to clip those inputs, given the amount of attenuation following the distortion stage.