Sunday, 24 March 2013

Citrus Graphic MKII

*Errors at the tone stack section have now been fixed...
*Errors in the schematic (
coupling caps at 0.068µ and not 0.68µ) have now been fixed on the layout...

As requested. Paul Nelson's Orange Graphic MKII stomp box adaptation. I knew this one will get huge the minute i saw the schematic, but it turned out a lot more compact in the end. Even got it nice and relatively symmetric. The FAC switch is a 2 pole 6 position rotary. If you're not familiar with how to wire those, check out Mark's layout for Rangemaster with switchable input caps to get a hold of it. 2N5457 and J201 were suggested for transistors, but you could try out any JFETs you like. Trimmers are used to set the the Drain voltages for ~4.5V.

I've tweaked the FAC cap values for not chaining all the caps after each other, so that part is not 1:1 with the schematic, but the values should be close enough.

With a rotary switch and 5 pots, this won't be a simple task for fitting it in 1590B, but i think it may just barely be doable :P


57 comments:

  1. This comment has been removed by the author.

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  2. Is this anything like the OLC (Runoffgroove) Orange peel?

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    1. OLC Orange Peel seems to be refined (OLC modded) adaptation of MKI, so these two should be close. Couldn't find much real info on either one.
      +m

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    2. Thanks. For quite some time I've been interested in getting into one the Orange amp circuit simulators. This could may well be the one to start with. The OLC-ROG design is quite difficult to get.

      Didn't find the schematic on Paul Nelson's page...

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    3. That's because the schematic for this isn't there. If you google for "Citrus Graphic MKII", you can find it from about 5 different forum threads.
      +m

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    4. Orange Peel is pretty similar up to Q4, then there's some clipping diodes, one more JFET, and some different filtering to the output. I'm finishing up a proper schematic if anyone wants to have a go at a vero layout...

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    5. Yes definitely, post it up when you're done. Nice one Lenny

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  3. I found one clip http://www.olcircuits.com/audio//olc_orangepeel.mp3

    Orange Peel Gain at 3 o'clock, bass and treble at 12 o'clock, filter at first position.

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    1. As said before, this is not the Orange Peel, although there are similarities..
      +m

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  4. Hi Ya,thanks for the cool layout. You guys do us DIYers a great service.
    so much stuff to choose from.

    On this layout, the 1meg resistor off the "boost1" doesn't go anywhere.
    I have an extra rotary switch, so this would be great to build.
    Thanks again.

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    1. Keen eye! Thank for heads up. That seems otherwise correct, but the cut on the left side of that resistor is leftover. The resistor should be coming from Q3 gate to ground. I'll post fixed image in the morning...
      +m

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  5. The 1M resistor from Boost 1 isnt connected to anything on the upper lead

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  6. Something is amiss. Im getting crazy oscillation. I double checked the layout but havent compared to the schem yet.

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    1. Check the input strip. There is a cut missing, so the input connects to to the output filters.

      ..and the 2n2 on right bottom ges one row too low.

      That's it. Hope it works...

      Updating the layout right now.
      +m

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  7. Tis good to go now. VERIFIED!!!!!!!!!!!!!!!!!!!!!!!!!!!!

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    1. Brilliant, top man! You get the "big layout" prize of the day! :)

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    2. I dunno man, i got it running but somethings weird around the FAC switch. the 4n7 from SW5 and the 2n7 from SW4 both go to SW6 and positions 4 & 5 on the switch dont work. Sounds and works great in position 6, though.

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    3. Lenny: I believe you must have something wrong with your build. all the switch caps connect to 100K resistor(going to Q3 gate). Tiny solder bridge perhaps?

      Onthetundra: Thanks!
      +m

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    4. Thats what i get for leaving out the short jumper on the right side. And then trying to figure it out from the Citrus schematic where the caps are wired in series between the switch poles. DUH!

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    5. And yeah, works and sounds fantastic! Thank you!

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    6. Haha :) Happens to all of us :) (last night i was baffled because one of my newly built Deep Blue Delay boards had only one repeat - knifed the gaps and it came to life..)

      First i drew this like it is, but with original cap values on the FAC. Late the next night i looked at the schematic again, and noticed that the it has all of those in series. I was like fu*k-fu*k-fu*k! But then i realized that there's no need to wire them in series and redraw the whole layout. Calculated the values and swapped them. So those should be really close to the original values :)
      +m

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  8. would someone please print up some t-shirts with the phrase " knife the gap". That way, we could identify each other in public...

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  9. You know, this layout could be made more compact if we used the stock FAC cap values mounted in series across the lugs of the switch, off the board. Would also mean only two wires to the switch. :)

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    1. Probably. But i for one am deeply against mounting components on switches and pots. And due to trimmers, it would shave off only couple columns.
      +m

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    2. I totally agree. Decided against building this one because all the values are loaded on the board and not the switch.

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  10. I built this one, but mine doesn't work at all. i'm just getting squeals and oscillation. looking at the actual schematic for it, the 1n5 cap doesn't connect to the 22K resistor to ground on bass lug 3 so what's up with that? the schematic shows it going between treble 3 and bass 1, so I tried that and it still doesn't work.

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    1. I got the boost & master volume work on mine, but IMO, there's definitely something wrong in the eq part of the circuit.

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    2. Just posted a fix for the tone stack. I can't see anything else wrong in there...
      +m

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  11. Care to expand on what the fix is Miro, I don't have a copy of the layout pre the fix and a combination of a packed board and tired eyes are making it hard to spot, thanks.

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    1. Only fix yesterday was the 1n5 cap and the treble 3 wire.

      I'm swapping the bass wires right now..

      Sorry for all the extra hassle..
      +m

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  12. to me it's funny that some verified it before the fixes. mine's still not working even after them. I've checked everything 4 times (bridges, trace cuts and component locations but it' still oscilatting. I even bypassed the FAC but have the same result. i'll check it a few more times before I give up on it.

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  13. okay, I finally got mine working. lugs 1 and three on the bass pot should be reversed so that CW has more low end. IMO, to match an actual Orange amp, the upper leg of the 1n5 cap should actually connect 5 rows down to the 100K/680n junction. also the FAC doesn't really work in the correct manner, i.e. get progressively brighter as you roll it CCW. it's all over the place and gets bright, dark, less bright etc. I actually prefer mine without the FAC so i'm bypassing it on mine anyway.

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    1. I'll swap those wire labels right now.

      The 1n5, to my eyes at least, matches the schematic. Bypassing the FAC was recommended on the DIYSB thread too.

      It's pretty rare that someone builds a working board when there's still an error on the drawing. I think i remember three cases. I'm not saying that the person who built it the first time doesn't have his working..
      +m

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  14. yeah. you have the 1n5 in the correct position now as per the nelson schematic, but the schematic had other errors like the 220n bass cap that should be a 22n (your's shows a 22n), so i'm assuming his placement of the 1n5 is incorrect too. also the 680n caps don't have to be that large either as the original amps had 68n's in those positions.

    I built an Orange Peel first, which is very similar all they way up to the boost stage and it works great, but it's quite a bit noisier than this schematic.

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    1. Whoa. I read only about the wrong 220n value, but seems there a lot more wrong with the schem.. Do you have the schematic for Orange Peel? I'm just thinking that it could be less noisy with a few smartly placed small caps.. And i couldn't find the schem for that anywhere - That's why i drew up this. It was a request from a friend.
      +m

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    2. I couldn't find the schematic for the orange peel either but I built one based on a perfboard layout that I found. I suppose that I could draw up a schematic from it though.

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    3. BTW, here's a pic of my Orange Peel MKII:

      http://johnkvintageguitars.homestead.com/Effects/Fuzz-ODs/OrangePeel/OP-01.jpg

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    4. Spotted that on the forum earlier. Amazing works as always.
      +m

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    5. BTW, IMO, once corrected, the Citrus sounds ALOT better than the Orange Peel.

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  15. Could anyone help me with adding a f.a.c. control to a pedal? or at least point me n a good direction. is it just caps wired in series to a rotary switch or are there resistors involved too?

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  16. what would it be? 'mid the double links "

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    1. "Mind the double links" means that there are two links connecting in one hole in the spots with blue dot.
      +m

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  17. I recommend switching the 680nF caps with 68nF caps as in the original schematic. It had an annoying, gated feel with the bigger caps but now it sounds like it should. A fun build!

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    1. Not quite sure what you mean by original schematic.. Probably a Orange 120W Graphic head schem? This one has them at 0.68µ:
      http://i13.photobucket.com/albums/a264/pbrommer/MKIIOrange.jpg

      Although. The DIYSB thread says that those values are a "Just a simple mistake."
      http://www.diystompboxes.com/smfforum/index.php?topic=46492.20
      So yeah. I'll update those values...
      +m

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  18. Any advice on installing the trims? Also what is the RLED and LED+ specifying here? Thanks!

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    1. RLED is the resistor for your LED (1K for diffused red and so on), LED+ connection is where you connect the anode of your LED. Cathode goes to your bypass switch as described on the outboard wiring page. I used to place those on some boards at one time.

      Please specify what you mean about the trimmers. I'm not exactly sure what you mean..
      +m

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    1. Usually the box takes most of the oscillation away once there's grounded metal housing around the circuit. Or does yours do it inside the enclosure?
      +m

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  22. Hi, i read all this discussion oft the layout above. My 1st question is: is this verified by one oft the admins? And 2nd are there other Layouts for orange-emus beside the Monarch?

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  23. I'll (finally) build this. I just wanted to remove the FAC, I think it could reduce the size of 2 or 3 columns. Anyone have a vero without FAC ?

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  24. Is there any simple way to have bass and treble equalizers work with each other to create a "presence" control that uses a single pot?

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