Thanks Mick, I'll give that a go and see. I thought it may have been the diode but i don't have another one to try.
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Thanks Mick, I'll give that a go and see. I thought it may have been the diode but i don't have another one to try.
Quote:
Originally Posted by Andy40
It shouldn't make much difference if you use CMOS 4049 instead of a CD4049UBE, the CD4049UBE is a Hex Inverter IC, that's made using CMOS (Complimentary Metal Oxide Semiconductor) technology, the "CD" in the IC type number indicates that it is a CMOS Device, it may be that the CMOS 4049 might have suffered from ESD (Electro-Static Discharge) damage, which most of the early CMOS devices were prone to until manufacturers started incorporating ESD protection in them.
You could also try using a CD4069 because it is a Hex Inverter too, although the pinout might be different, they are both functionally the same.
The 1N5817 is a Schottky Rectifier Diode with a forward voltage drop of about .3V as compared to a 1N4004 which is a standard silicon rectifier diode with a forward voltage drop of about .6V and a PIV (peak inverse voltage) rating of 400V, that really shouldn't have much effect on the operation of the circuit.
Thanks doc. That was an awesome explanation. Have you any suggestion regarding the issue? If you need a sound sample I can put one up
Quote:
Originally Posted by Andy40
Might be a good idea to put up a sound sample so we can hear what's going on, when you turn up the gain, does it sound like it's going into self-oscillation?, if it does, you could try connecting the metal plate of your breadboard to circuit ground and see if that fixes it, I had that happen to me once when I was breadboarding a circuit on one of my breadboards, soon as I connected the metal plate to circuit ground the circuit started behaving normally.
From looking at the Snarkdoodle circuit, it looks like it is based on the Tube Sound Fuzz circuit that was designed by Craig Anderton, who included it in his book "Electronic Projects For Musicians", I've built the circuit before and managed to get it working pretty well on a piece of Veroboard, I might have a go at building the Snarkdoodle one day.
Sorry for the double-post, Firefox was behaving a bit weirdly and wouldn't let me edit my previous post cause the keyboard wasn't responding, had to restart my laptop to sort it out.
Anyway, in the Snarkdoodle circuit each of the used inverters are actually not used as inverters, they are actually being used as amplifiers by being made to work in their linear region, in the circuit diagram, you can see a resistor (R3 in conjunction with a 1M pot, and R5 1M) going from the output of each of the used Hex Inverter stage to the input of that stage, this negative-feedback resistor sets the overall gain and makes the inverter work as an amplifier.
The pot in series with R3 gives us a way to control the gain of the first inverter stage, you will also notice that there's a small value cap in parallel with the resistor, this is to prevent the inverter stage from going into self-oscillation, to further stabilize the circuit, I would put a large value cap across the points where the 9V battery connects, maybe say a 100uF to 470uF/16V cap.
I think it already has the 100uf cap - it is c6 in the schematic?
I reckon play around with the r3 and gain pot, see if a different value will get the sound you want. As DrNomis said, they are setting the gain factor on that first stage.
You might also find that the circuit is quieter and less distorted once you get it on the PCB. I find that bread boarding will sometimes introduce a whole bunch of noise due to the wires going everywhere.
Wow Doc! its like someone turning a light on in the dark! totally makes sense.
The gain pot doesn't do a lot till you turn it waaay up.
Heres a link to a sound file. https://soundcloud.com/andy40-923020...k-doodle-test1
Sorry is not a real amp, but it sounds the same going into my Blues Cube. Its going into my Zoom G3X Pedal. I think I just used a tweed amp simpulator with some reverb and my Pitbull ST-1 going into the Sanrkdoodle circuit.
For the first minute, I have the gain turned right down to 0 and I am just increasing the volume up at stages.
From 1:00 min I turn the volume down a bit and turn the gain right up, then I increase the volume at 1:25min and you can hear it start to not handle it - that's my problem right there.
Quote:
Originally Posted by Andy40
You could try reducing the value of the coupling caps between each of the inverters, that will reduce some of the bass frequencies, I'm assuming that's what the problem is, too much bass in the tone, I'll have a look at the circuit again and post some suggested cap values to try.
Okay, you could try reducing C3 to 22nF (.022uf, or 223), and C5 to maybe 100nF (.1uf, 104) and see if that sorts it out.
I may need to breadboard the circuit so that I can see if I can figure out exactly what's going on and maybe tweak some of the component values.
Update:
I just had another listen to your demo and I made sure I paid careful attention to what I was listening to as it got to the 1:25 mark, and I see what you mean, it seems to go a bit glitchy there in comparison to the smoother sound you get at lower gains, hmmmmm.....try giving those cap values I suggested a try and see if that gets rid of the problem.
Yhep, you are right C6 is a 100uf 16v electrolytic capQuote:
Originally Posted by mjg
Yhep again Matt, there is definatley an overall buzzin that i thought may be reduced once on the PCB and boxed.Quote:
Originally Posted by mjg
alright I'll try changing R3 to either 50k or 200k and I think ive got a 500k pot somewhere here too! I'll also try connecting the metal plate of my breadboard to circuit ground
I'll also try reducing C3 to 22nF (.022uf, or 223), and C5 to maybe 100nF (.1uf, 104)
Thanks guys you really are helping me out!
Quote:
Originally Posted by Andy40
No worries mate, hope that sorts it all out, when I get round to breadboarding the circuit I might make some mods to it, like maybe add a tone-stack of some kind to it, I'll post the mods in this thread.
Tried different caps and resistors, earthing it to breadboard. nothing really worked, some of it made it worse. It may be an issue with the circuit being open on the breadboard.
I've moved on to double check the PCB with the multimeter and populate the pcb!!! :eek:
Quick question though as you can see on the silk screen I can identify, G for ground, In and Out and the LED....but what is "L"? its got me stumpted
Quote:
Originally Posted by Andy40
I just had a look at the circuit diagram and the pad marked "L" goes to the cathode lead of the Led, so, I think that pad marked "L" is where you solder a piece of wire that goes to the footswitch so that it turns the Led off when you stomp on the footswitch to bypass the effect.
Thanks doc!
No worries mate.
Yep, the 'L' pad is the one that you connect with wire to the 3rd pole of the foot switch. It's done that way on all the Madbean PCBs that I've seen.
The LED itself goes into the '+ LED '-' pads.
Note that R7 is the current limiting resistor for the LED, and depending on what colour LED and how bright you want it, you may need to adjust that resistor value. If you've got one of those super bright white or blue LEDs, you will probably want a higher resistor value in R7. I'd double check your LED and R7 on breadboard before committing to soldering that one in. Speaking from experience... I've made that mistake more than once. :)
If you're running your Snarkdoodle off a 9V battery, and you decide to use a high-brightness Blue Led as the indicator, then a suitable resistor value for R7 could be anything from say 22k to something like 56k, personally, I got pretty good results using a 47k current limiting resistor with the Blue Leds in my pedal builds that run on a 9V battery.
As its a red pedal (and I don't gig, I'll probably use a high Red LED. (I managed to blow my last one testing the pedal).
Here's what i got up to today..
Attachment 19073
Poured multiple cups of coffee and tested the circuit with a multimeter (couple of faults - not bad) - fixed faults
Populated the board and soldered it up (a few boo boos) best damn soldering job i think i've ever done!.
Rocked it before i boxed it!
Attachment 19074
Drilled most of the enclosure in a 1590G
Attachment 19075
Put it together....
Attachment 19076
Thats it till next time folks.....
Looks good!
How did you find the sound once you got it on the PCB?
Looking good there mate, so I'm assuming that you're going to be spray-painting the pedal a Red colour then?
I finally got all the electronics in my Gold strat all working a few minutes ago, all the new Kent Armstrong Dual-Blades appear to be working, as does all the controls, I just need to wait till next week to buy some strings so I can string the guitar up, set it up, and then do a demo of it.
It's coming together nicely Andy - cant wait to hear the result
Thanks Guys, yeah Matt, it sounded pretty good before I boxed it. Sounded much better than on the breadboard.
Then disaster struck.
She no work...
I think I burnt the pots out cutting the long shaft with my dremel..... How do you guys cut your long shafts?
dang....till next weekend.
Quote:
Originally Posted by Andy40
To cut the shafts of the 24mm Alpha Pots I use to build my pedals, I just use a small bench vise, a standard metalworking hacksaw, and a fine felt-tip blue sharpie to mark where to cut, had no problems with pots not working with that method.
I use my rotary tool (rip off brand of the Dremel) to cut the tops of pots. Haven't had issues doing it that way.
Might be something else is making it not work - something shorting out in the enclosure when you put it in? Maybe the switch isn't wired correctly?
Do you get a bypass signal working through the enclosure when you stomp on the switch? If that also doesn't work, might be the switch.
Another thing to check first up - use your multimeter to double check that power is getting to the board.
Yeah, everything was working sweet all wired up (just no LED) then as soon as I cut the tops off the pots I noiced how unbearably hot they were. then suddenly the circuit doesn't work whether it was in the box or out. My multimeter is the next step...just got to find the child free time.....;)
Quote:
Originally Posted by Andy40
I'm guessing that it's probably just a bad solder-joint somewhere that got disturbed, also, check to see if any of the solder lugs on the pots are a bit loose, I've sometimes had some pots develop loose solder lugs after I've soldered wires to them, if you find any pots with loose solder lugs it's best to just replace them with a good one, hope that helps, let us know your findings.
Sometimes the footswitch solder lugs can go a bit loose too if you apply heat for too long on them, that could be the reason for the Led not working, also, check the voltages on the components when the pedal is powered up with your multimeter, if some of the voltages look a bit off then it's probably a faulty component that's related to it that's causing it to be a bit off.
make sure you don't have a bit of wire or a component shorting somewhere, on one of my pedals I had a bit of wire I'd soldered into the PCB shorting on the enclosure killing the pedal (it was on one of the jacks)
Good luck debugging it Andy. Good luck finding the child free time too.
How old is the child? Once they are old enough to read the letters 'R' and 'C', and numbers 1-20 or so, you can use them to populate the circuit boards for you. :)
(And once they are old enough to hold a pencil, and understand the sentence "Arrrhhgg, no, that's too much solder!" they are ready to learn soldering too ;) )
Good plan, historically child labour has been used to cheaply increase production...
Didn't happen until you cased it Andy - it's an obvious statement, but there is probably the best place to start the search. Not working and heating pots certainly suggests a short , good luck
You give me such good ideas MattQuote:
Originally Posted by mjg
I'm wondering if the initial problem, the 'rough' sound with the gain turned up, is simply due to the signal being too hot for the Zoom and Roland inputs and you are getting digital clipping as a result? Both are DSP based units so will have maximum signal levels that they can cope with. Exceed those and the tops of any waveforms entering get straight-line clipped. Not nice sounding. You won't get a similar issue with a valve amp. It can happen with modelling amps like the Kemper if you use a really hot pickup in your guitar and don't adjust the input attenuation to its maximum attenuation level - let alone the output from a high-gain drive pedal.
If you keep the output volume low, do you get a similar effect with the gain turned right up?
Also, did you pick up from the circuit diagram that the gain pot is a linear type whilst the volume pot should be an audio type?
Hi Simon,
I had the same thought...alas my mates tube amp (and my only easy access to one) had died recently so I couldn't run the test.
You are right though about the volume, its only when the volume is turned up max with max gain does it do it. you only have to back the volume off just a fraction (not even very low) and it sounds sweet.
I'll double check the A and B type pots when i get some time.
right so actually nothing wrong with the pedal. I just used cheap jacks and the hot tip had spun inside the box so it was touching the earth.
I better start thinking of ways to put a finish on the pedal.
Whats cheap and easy? rattle cans?
Quote:
Originally Posted by Andy40
Yep, rattle cans are cheap and easy enough, and I got pretty good results with that on some of my DIY pedals, you'll need to buy yourself a can of the colour spray-paint you want to use, a can of White Knight Clear Gloss Lacquer, and if you're using a diecast aluminium box from Jaycar Electronics as your enclosure for the pedal, a can of grey etch primer, another thing you might also want to buy is some sheets of rub-on lettering which you can use to do the labeling.
You can buy the spray paint, clear lacquer, and etch primer from your local big green shed.
Seeing as I'm going to be giving my two DIY Tonebender pedals a new paint-job soon, I might see if I can do a mini-tutorial on spray-painting/labeling DIY pedals, since I'm guessing that it'll be of great interest to DIY pedal builders.
Actually, if there are any forum members who are interested in me doing a mini-tutorial on spray painting/labeling DIY pedals, feel free to let me know.
Ahh the joys of cheap jacks. Good to hear you got it working.
Glad it was an easy fix, got any wild colours planned?
So its boxed and working! yay me
buuuuut, I think i either got the pots wrong or wired them wrong because anticlockwise increases volume/gain :confused:
Quote:
Originally Posted by Andy40
I think I may have done that in the past, wired a pot backwards, all you need to do is swap the two outer-wires around and it should work correctly.
So. Back to this pedal. Pots are rewired (yay) and time for some decoration. https://uploads.tapatalk-cdn.com/201...71618c832d.jpg boring
https://uploads.tapatalk-cdn.com/201...5dfb6e1e72.jpgschiniehttps://uploads.tapatalk-cdn.com/201...2f79f442e2.jpgundercoat. Getting there
Looking pretty good there Andy, so what colour do you think you'll go with for that pedal?
POSCA Pens!