Building the Christine oscillating fuzz PCB

[Taylor]

Ah yes, I did not notice this before, but it does look like your diode is backwards, which would cause the effect to not work at all. It's very likely that that's your problem (or at least the first thing to fix). Diodes, including LEDs, have positive (anode) and negative (cathode) leads. The cathode is marked with a band on one end, and most PCBs including this one have a line or band on the part in the silk screen to show which direction to put it. Otherwise they might have a + or - symbol to show orientation.

[jwar]

So I checked the diode and get a good reading off of it. So the problem could be in one of the resistors or the caps. Crap. I'm going to check the IC next just because it's easier to pulled since I put it in a socket.

Quick question though. The schematic shows that there is a ground needed for the input and output jacks. Can the box act as the Input ground? Or does it have to have a wire run to ground it?

[Taylor]

Your diode is definitely backwards in that picture. Did you flip it? If so, what are the symptoms now?

The box can connect grounds, but I don't think it's good practice to rely on it. If the jacks become loose your pedal will stop working. If you really want to do that, use some heavy duty lock washers.

[jwar]

Your diode is definitely backwards in that picture. Did you flip it? If so, what are the symptoms now?

The box can connect grounds, but I don't think it's good practice to rely on it. If the jacks become loose your pedal will stop working. If you really want to do that, use some heavy duty lock washers.

I have since cleaned up the wiring and flipped the diode, which I was getting a good reading on. So it should work.

I just grounded the input jack and no change other than the LED is now not working. So I need to double check my connections. I think I'm going to break down and try to find the bad component with a cable like the link suggested.

So right now I get a bypassed tone and that's it. The LED leads somehow twisted in the enclosure though, so I may have a bad LED (simple enough to replace).

[Wayneland]

I've built several pedals from kits but this is my first non kit build and I'm a little confused about capacitors.  First question:  Will the capacitor with SKU # 1155 from small bear work for the "100n boxed metal film" cap?   It's labeled as .1mf  on the small bear site which I believe is the same as 100n. 
Second question:   are capacitors rated at 16 volts enough for this pedal?   I'm looking at sku# 1404 and 1406h on small bear for the rest of the caps.  They are rated at 16 volts.  I have a feeling they should be at least 18 since the pedal is powered by 9 volts. 

Thanks for the help.

[Taylor]

I've built several pedals from kits but this is my first non kit build and I'm a little confused about capacitors.  First question:  Will the capacitor with SKU # 1155 from small bear work for the "100n boxed metal film" cap?   It's labeled as .1mf  on the small bear site which I believe is the same as 100n. 

Yes, that will work, and you're right that ".1mf" is the same as 100nf, at least with the way Small Bear labels things.*

Second question:   are capacitors rated at 16 volts enough for this pedal?   I'm looking at sku# 1404 and 1406h on small bear for the rest of the caps.  They are rated at 16 volts.  I have a feeling they should be at least 18 since the pedal is powered by 9 volts. 

Thanks for the help.

16 volts is probably fine for any non-polarized part like film capacitors. To my knowledge, it's only when you are buying electrolytic capacitors that you really need to over-rated them by a lot, because operating near their rated voltage can cause distortion and short life (leaking, explosion). This is assuming that you are building this pedal for yourself and you know that you will never plug in an 18 volt power supply. If you are building for other people, different rules apply.

* Most shops/companies/people I know or read do not call 1 microfarad "mf". They will normally either use the mu symbol (μF) or, since it's not so easy to make a mu on a keyboard, most people just use "uf". This is technically wrong, but so is mf, and the latter can get you into trouble, since in actual metric prefixes, a lowercase m stand for "milli-". Small Bear is the only shop I know that uses mf.

[petey twofinger]

put together a christine yesterday . the pcb is very nice , easy build , i populated it in a half hour , had it all boxed up the next day , due to paint dry time . i tried 3 different 4049's in it , i do not have the "crazy " version , but i will see about getting one eventually just for "fun" . i did notice a SLIGHT difference between the chips , very slight , when playing an 'A" one had no sustain , one did a "step down " note effect , and the other had slightly more sustain , but very minimal differences .

i tried it with a jfet buffer , a mosfett boost , and a FTM in front . i think i prefer the mosfet boost in front . tried a humbucker guitar , strat , and a fernandes w/ actives / sustainer . i was getting some very odd timbres with it , especially set to self osc. i think w/ proper technique i could do some musical stuff (lead) using it besides just noise . shutting it off during dead spots, or not pausing much when its on . this thing makes quite a racket ! will do a demo video sometime .

i would like to try it out in combo with more pedals when i get some tinker time , i will say , with nothing in front of it , with my strat , the effect was almost non-existent , unless i strummed very hard . i am curious if i may have screwed something up with the build or if its the way it is normally .

i also got 2 echo pcbs from musicpcb.com . cant wait to do those , rather , till they are finished . its a lot of components and i am such a noob ! but yeah , it was a treat working with the quality pcb from these guys , as opposed to vero . the whole build process was no sweat ( fun too ).

its the one on the bottom left ;

[danndubblewe]

SO!  I just finished building up Christine and it rules!  Those oscillations are insanely loud and so much fun with the onboard controls of my bass.  One thing that is just incredibly weird though - my LED blinks when the effect is engaged.  Like, on - off - on - off - on - off...you get my drift.  I initially thought it was a electrolytic I had accidentally touched with my iron but after replacing it it was still doing it.  The effect works (and is insane) BUT it's just weird that I have a pulsating LED...maybe I'll try a different type and see if that makes any difference.  DERP.

[danndubblewe]

Well, to answer my post...yeah.  It was the LED.  Sup with that?  Changed it out to a different color and all is well.  The one before was a UV one and it seems like something else is going on in the component itself, but it's so hard to actually see. 

Oh well!  Sorry for the virtually meaningless post.  I guess it was cool to have a blinking EVERYTHING IS GO light

Awesome boards Taylor!  Can't wait to get the Tap Tempo trem boards in.  PUMPED.

[Taylor]

Apologies if this is too obvious an answer, but there are some LEDs with impossibly tiny circuits inside (invisible to the naked eye) intended to blink the LED. They are indistinguishable from regular LEDs if you buy a random pack. If it's blinking in a random-ish pattern, it can be a bad solder joint or just a dodgy LED (I have experienced the latter before).

[Wayneland]

I've built several pedals from kits but this is my first non kit build and I'm a little confused about capacitors.  First question:  Will the capacitor with SKU # 1155 from small bear work for the "100n boxed metal film" cap?   It's labeled as .1mf  on the small bear site which I believe is the same as 100n. 

Yes, that will work, and you're right that ".1mf" is the same as 100nf, at least with the way Small Bear labels things.*

Second question:   are capacitors rated at 16 volts enough for this pedal?   I'm looking at sku# 1404 and 1406h on small bear for the rest of the caps.  They are rated at 16 volts.  I have a feeling they should be at least 18 since the pedal is powered by 9 volts. 

Thanks for the help.

16 volts is probably fine for any non-polarized part like film capacitors. To my knowledge, it's only when you are buying electrolytic capacitors that you really need to over-rated them by a lot, because operating near their rated voltage can cause distortion and short life (leaking, explosion). This is assuming that you are building this pedal for yourself and you know that you will never plug in an 18 volt power supply. If you are building for other people, different rules apply.

* Most shops/companies/people I know or read do not call 1 microfarad "mf". They will normally either use the mu symbol (μF) or, since it's not so easy to make a mu on a keyboard, most people just use "uf". This is technically wrong, but so is mf, and the latter can get you into trouble, since in actual metric prefixes, a lowercase m stand for "milli-". Small Bear is the only shop I know that uses mf.

Thank you so much for answering my capacitor quandary.  It really made my day that you answered so quickly and that I also managed to figure it out correctly.  I'm stoked to build this.  I'm building two for friends.  They're gifts not things I'm selling.   
Your answer to my question inspired another question. 
In what scenario would I or someone else hook these up to an 18volt power supply?  Just curious.

[danndubblewe]

Apologies if this is too obvious an answer, but there are some LEDs with impossibly tiny circuits inside (invisible to the naked eye) intended to blink the LED. They are indistinguishable from regular LEDs if you buy a random pack. If it's blinking in a random-ish pattern, it can be a bad solder joint or just a dodgy LED (I have experienced the latter before).

That's what I assumed.  As far as I could tell it was a non-random, very precise pattern.  It was cool!  But a little aggravating if it means nothing.  Neat to know I had a random pack of blinky LED's 

On another note, I'm getting some pretty noticeable whine in bypass, like something is "winding down" or something?  At any rate, I DID purchase a new iron and for some reason I decided to start on this board and it's covered in cold joints (and my shaky hands proved to make it nearly impossible to desolder with the cheap pump i have).  I figure that's where my problem lies - I will probably just populate the second board with my now correct-temperature-set iron and see if that solves the problem.  And still, the sounds coming out of Christine are just mind boggling.  It's play with the instruments electronics is insane!  So many tones, so little time...

[Taylor]

In what scenario would I or someone else hook these up to an 18volt power supply?  Just curious.

The typical one involves someone needing to plug in their pedal, and not knowing that there's a difference between different power supplies. The other one, which stings the best of us, is simply having two different, incompatible supplies which have the same physical plug, lying around the floor of the studio/practice space/gig bag, and not paying attention as we plug in and fry our pedal.

A third scenario is becoming increasingly common: guys who "know tone" post on blogs or forums that X pedal sounds double-good when you power it with 18 volts. Sometimes this is true (or at least a matter of taste). Then people get the idea that "more volts=more tonez," and they figure every pedal they own will sound twice as good with twice as many volts. You see where this goes.

One last situation that I've encountered is that, some of the modern pedal power bricks have a bunch of 9v outs, some 12v outs, and then a few assorted weird outputs. Owner of said supply finds that he or she has used up all the available 9v outputs, and attempts to use an 18v output, since that's all that's left.

TL;DR version: One shouldn't do that, but sometimes people mess up or have the wrong idea.

[Sid Nitzerglobin]

Sorry for the thread necromancy but I figured this was the right spot.

I think I'm finally ready to build my Christine fuzz and would like to incorporate the Sag bypass mentioned earlier.  Does the layout pictured below seem like a functional way to do that?  I figure I'd socket the resistor on the bypass side of the switch. 



I've built a couple of BYOC kits so far but I'm still a noob at this stuff, so pointing out any other glaring errors in the layout would be much appreciated as well.  Thanks!

[Taylor]

I looked back over this thread but couldn't find the sag bypass to which you're referring, could you quote or link it please? I guess it's just a pre-set value for the power pot?

I think you might not be using the LED+ pad correctly - it is fed by the 4k7 to the right above it so you don't need to add what you've labeled R19. Then connect your second LED and your R20 directly to 9V either at the PCB inlet or on your power jack.

[Sid Nitzerglobin]

The starve/sag bypass was mentioned here in post #29:
http://www.diystompboxes.com/smfforum/index.php?topic=90403.msg774799#msg774799

I just kinda latched onto the idea of the sag bypass and figured "hey, if I put a static resistor on the "bypass" poles I could have a couple preset sag values to switch between rather than just on/off or jumper the sockets if I want a bypass..."  I'm taking Power pads 1 & 2 and switching between posts 1 & 2 on the Sag pot and the leads of R21 while leaving post 3 (which I assume is ground?) wired to post 3 of the pot.   Make sense?

Good info on the LED + pad, I was assuming it was just a straight 9V lead.  I'll pull out R19 and move R20 to connect to + on the DC jack.

Thanks again!

[rumbletone]

Hi all - I just built a Christine Fuzz and the build went great (quick and easy and worked with no troubleshooting required!). However, I'd really like to try it with the mc14049BCPG - anyone know a source that currently has them available? They come up in lots of catalogues (Mouser, et al.) but no one seems to have any available in stock - any leads would be much appreciated!!

Thanks

[Taylor]

Hmm, that's a bummer. There is a seller on AliExpress selling them:

http://www.aliexpress.com/item/MC14049BCPG/1035932148.html

AliExpress is kind of like ebay but all of the sellers are in China. I've bought things on there and received them with no issue.

[Taylor]

After being gone for a long time, the Christine PCB is finally back in stock:

http://www.musicpcb.com/pcbs/christine-fuzz

[blacksock]

Hey there,  I am noticing a osc. hum or feedback on the pedal at most times, it recedes when instrument is played. I am using the mellow IC at the time. Is this normal? I'll try a new IC when i can get one. Thanks