just built my first boost pedal from a schematic. i'd previously built my first pedal using the GGG BMP kit. this boost was the first one i built simply following a schematic.
its a simple boost with a pot, switch, and led. problem i'm having is that, while the pot is at 12 o'clock, there is a volume drop when the effect is switch on. when the pot is set to max, there is only a very, very, slight volume boost, if any at all. there is also a noticeable treble roll-off or presence cut.
this is the boost circuit: (http://www.lbs-band.com/webphotos/BradWorld_LPB_Vero_v1.2.gif)
this is the switch layout i used: (http://www.lbs-band.com/webphotos/3PDT%20True%20Bypass%20Layout.jpg)
I substituted R1 with 330 ohms. I substituted R3 with 820K ohms. Everything else is hopefully as it should. The effect seems to function exactly as it should except for the lack of volume and tone cut. I'm not sure if this is due to a circuit problem or due to the substitutions that I made.
IF it helps... I originally had the positive circuit supply attached to one of the positive lugs of the DC jacks, and the led hooked up to the other positive lug. when i had it hooked up this way, i was only getting 9 volts from ground to the positive lug that had the led was attached to. there were no volts to the other positive lug. when it was wired like this, everything functioned as it should, except there was an extreme volume cut when the effect was on. i then moved the positive power line (to the circuit), to the same lug that the LED was attached to, which I knew was getting 9 volts. This is the configuration it is in now, which improved my volume, but still seems to be lacking.
and FINALLY :D hi, my name is C.J., and I plan to be here often. sorry for the lengthy first post!
Hello and welcome to the forum!
Quote from: cgibsong002 on November 15, 2010, 10:29:33 PM
I originally had the positive circuit supply attached to one of the positive lugs of the DC jacks, and the led hooked up to the other positive lug. when i had it hooked up this way, i was only getting 9 volts from ground to the positive lug that had the led was attached to.
FYI - on most of the DC jacks we use there are 2 positive lugs as you mentioned; the interior one is for the batter snap connection. When there is no plug plugged into the DC jack they are jumpered together, but when you insert a plug into the DC jack it disconnects the battery connection. Otherwise bad things would likely happen. So always use the outer lug, the inner one is for the battery.
As far as your other issue, I'd double check for any solder bridges between tracks (vero is notoriously easy to get solder bridges on). Double check all component values. Also double check the pinout of your transistor.
Do you have a volt meter or a multimeter? I'd suggest getting one if you don't. It's almost impossible to debug without: a) a voltmeter, b) a continuity tester (a common feature on most multimeters) and c) an audio probe- which you can make easily... if you do a google search you can find a diagram. It will also be easier for people to help you if you can post voltages from your build.
And last but not at all least, look at this: http://www.diystompboxes.com/smfforum/index.php?topic=29816.0
Good luck!
thanks! i did take a look at that thread, forgot to mention i do have a multi-meter. not sure what type of values i can expect however. could you guys possibly run me through some measurements that might lead me to an indication of where my problem might lie? it might also be likely that my two cuts (as described in the schematic) in the board might not have been clean cuts. i used a screwdriver to just etch away at the copper strip at those two holes until the copper was gone. i'm fairly sure theres a solid gap, but i figured i'd at least mention if it helps.
also, about the dc jack, i was kind of thinking the same thing, that the other lug is only for the battery snap. i am, by the way, powering the pedal with a one spot dc adapter, with no battery snap connected.
not sure about voltage readings , but i'd look at that cut under r4, as well as reheat / resolder the volume pot connections... my money is on the r4 cut tho....
Your multimeter should have a setting that looks like a diode: -->|-- Sort of like that. On mine, when I have it on this setting it beeps when the two probes come into contact. So you can use it to make sure that a trace cut is indeed cut, and also to make sure that 2 traces that are adjacent aren't connected in some way. In short, you can use it to make sure that things that shouldn't be connected aren't and vice versa. If you don't have the diode thingy or some other continuity checker, you could use the setting that measures resistance. 0 ohms means there is a connection.
The best thing to do is follow the protocol in that Debugging thread and post your findings here. You are most likely to get help that way. You've already posted the layout you used and some general info about your build, which is really great, but now we need other info like voltages off of your transistor, etc.
that setting is actually a big help! i never knew what that was for. unfortunately, since this was my first real build, i didn't plan the layout so well. i have the circuit buried underneath all the wiring with the electrical contacts face down. so i've pretty much got to unsolder a whole bunch to be able to pull the circuit out. hopefully i'll have a chance to take a look tonight and report back.
Whenever I build a pedal I first solder up the circuit board with the pots attached, and with in, out, V+ and ground wires and that's it. I leave jacks, footswitches and the enclosure out of it until I know the circuit works. I take my board and hook up the ins and outs and power etc to some jacks and test it out before wiring it into an enclosure- just for that reason; it's often very hard to work on the circuit board once it's all wired up and crammed into a box.
yup, should've done that. was going to do that actually, but then i started looking at the diagram with the footswitch and saw so many wires i didn't know where to begin. i eventually just decided, screw it, just start soldering stuff and eventually you'll finish it. which worked, except for the fact that it doesn't work. i guess i didn't realize it's quite simple to just leave out the footswitch and all the extra wires associated with it.
You'll have to divide to conqueor the entire kingdom for your pathway and power.
The cable must be mono sleeve if input power trick-off jack is assigned [plug pull cuts power].
The guitar side tip of the cable must connect to the tip lug of the input jack.
Skipping for luck test, or stopping to stompswitch study to determine if 1/4 turn before soldering is necessary, then continuing continuity tests through to input of circuit board pad.
I always start with the non-V+/Gnd continuity test, as close as I can get to power supply [for no-short condition of power supply].
Passes ?...then voltage test the circuit pins.
Debugging, what to do when it doesn't work...read and follow, learn and debug electronics.
Eventually, all the paths are opened, the power supply is there, amplification occurs. It is conditional, a matter of determining what they are, and setting up certain conditions.
Sometimes the switch rotation is 1/4 turn off, requiring de and re soldering.
A 'Full Wrapper' box...with the full set of variables is host to many a conditions some of which are difficult to explain, this is why determining the source of the problem should be the 1rst order of preponderance.
An insulated testjig platform with 2 jacks three testclips [other clip-on or quick- to solder components like volume control are optional] makes it easy to put a battery clip on a circuit board and test it, tweek it, take it out of the debugging equation or fix it before it's 'embedded in the box/wrapper components with all their variables for problems.
ok. trying to make some progress here. got my circuit back out. my diode function seems to work differently. if i read my manual correctly, it seems to give me a voltage reading across the two points. so if there's a short, it would be 0. if theres a resistance, there should be a numerical value. one of my soldered points was bent towards the parallel contact strip and may have been making a connection. i fixed that. now i don't have any 0 readings across the two cuts or across any two parallel strips. i get some readings across some of the strips, but if i'm understanding the function correctly, that's simply telling me that those two strips are connected by a component, but not shorted together or else it'd read 0.
i didn't fully take out the circuit, but just disconnected enough wires to allow me to bring it to the top to work on. is there anything else i should look at or take readings of before testing it out again?
hoped everything was fixed, cleaned everything over and double checked everything, still same results. i'm going to try to switch out the 330 ohm resistor with a 390. it's still not the 360 that's called for, but I don't have one of those, and i have a 390 laying around, so hopefully that should at least indicate whether my problem is components or circuit issues.
edit: no dice. switched out the resistor, no noticeable difference. can't figure out the problem. anyone real good with either multisim or labview 2009? I have both and am fairly good with each, but don't know how i could simulate a guitar type input signal. I've built the circuit in multisim, but I've also heard it's possible to get a realistic input signal into labview and then import that into multisim.
Maybe a picture would help if you have one.
my camera isn't too good with closeups.. but maybe someone will notice something blatantly obvious that i assumed was obviously correct... i can take more if it helps
(http://img801.imageshack.us/img801/3936/1001951a.jpg)
(http://img804.imageshack.us/img804/7976/1001955.jpg)
(http://img209.imageshack.us/img209/5118/1001958p.jpg)
are the in and out jack's sleeves connected to the circuit board ground? can't tell.
We need voltages off your transistor
Quote from: Quackzed on November 18, 2010, 09:42:04 AM
are the in and out jack's sleeves connected to the circuit board ground? can't tell.
yes, i have those grounds and all other grounds attached to that extra little strip board
Quote from: MikeH on November 18, 2010, 01:41:18 PM
We need voltages off your transistor
across the outer legs (Drain to source? is this a mosfet?) is 9.15 V. across the two bottom connections is .54V and across the two top is 8.55V
sorry for my lack of knowledge... we learn about this stuff in circuits classes, but we don't learn much in terms of practicality and real life applications.
I would cut those long leads off that are just hanging off the board. It's probably not be the problem but it could cause other ones.
Quote from: blooze_man on November 18, 2010, 05:43:26 PM
I would cut those long leads off that are just hanging off the board. It's probably not be the problem but it could cause other ones.
yep, those two are just from the resistor that i just switched out. i didn't cut them because i was just testing to see if the different resistor would affect it. obviously it'll all be cleaned up much better once i figure this thing out.
I like to always run a screwdriver down between the traces on those stripboards...it's an easy way of ensuring there are no hairline bridges between the tracks after soldering..
J
It might just be me but the resistor (R1?... lowest in pic 2) doesn't look to be connected to the same strip as the others which should be the ground yeah? Also, I can't make out a wire link between this ground and the offboard grounds on the other piece of stripboard. That might just be the pics though. Also, get yourself a magnifier of some sort and look for solder bridges
lol, yeah, i really need a magnifying glass. and that resistor is in the right place, it's just bent under so it looks like it's going in the wrong strip (just a weird pic angle). i spent a good half hour going in between the grooves with a flathead and making sure there were no bridges. i'm really confused now as to whether this is a problem with my circuit, how the circuit is just supposed to sound, or i dunno. the guy that gave me the circuit originally designed it as a circuit to use as a booster into another circuit, with no controls or anything. so i'm thinking it's likely that this thing wasn't designed to give me the huge volume boost that i'm expecting. barring any other random thoughts or solutions you guys might have, i might just take the circuit out and replace it with something a bit different.
do you guys know of any other circuits i might be able to build using mostly the same components? i have a decent amount of extra resistors and caps of different values, but this transistor is the only one i have.
Triple check the pinout of the transistor too
Quote from: Cardboard Tube Samurai on November 19, 2010, 06:43:54 PM
Triple check the pinout of the transistor too
i assumed that the layout schematic was just set up to have it go in the same way it's facing in the layout.
if anyone can tell me what kind of current an electric guitar puts out, i already have my circuit made in multisim, i should be able to get theoretical voltage readings.
i took a look at the 5088 pinout as well as the lpb schem...looks ok to me.. are you sure that the 360r r1 is in fact just a 360r and not a 360k or something...?
(http://www.muzique.com/schem/lpb1.gif)
heres the schem , looks like its correct to the schematic...
?!? double check the battery?!?
360r(ohms) is correct.
Quote from: Quackzed on November 20, 2010, 12:46:44 AM
i took a look at the 5088 pinout as well as the lpb schem...looks ok to me.. are you sure that the 360r r1 is in fact just a 360r and not a 360k or something...?
heres the schem , looks like its correct to the schematic...
?!? double check the battery?!?
yep, R1 is correct (well, it's 390 not 360, also tried 330). Power source is good as it's not a battery, run off my 1 spot getting 9.48 or so volts.
So this is the original circuit, huh? Are any of you guys good enough to tell me how exactly these minor changes in the circuit will change the tone? I see the original circuit uses pretty much the exact same components as the circuit I was building, so I'm curious to know the differences. Today I'm just going to unsolder the whole circuit board and re-do it. If I'm going to do that, I'd like to know the differences in the two circuits so I can build the better one for me.
edit: i also just listened to a clip of the lpb-1. mine is definitely not working like that at all, that thing sounds just like what i'm looking for. i'd like to know the differences between the two if you guys could help out.
thanks!
390 vs 360 is insignificant, i don't believe there would be any difference 1 or the other... same with 820k vs 830k no significant difference...
generally you can imagine if your resistors are 10% tolerance, meaning they are the printed resistance +/- 10%, then changing one for another of less than 10% difference shouldn't matter...
as far as a .1 cap vs. a .15 cap... the .15 cap will cut slightly less bass but just slightly, so it shouldn't affect anything other than that...
all in all, your slight changes shouldn't add up to much difference at all. at least not enough to alter the function of the circuit..
btw you can get npn transistors at radio shack 2n3904 2n2222 2n5088 etc... are all good candidates for this circuit, i think they sell them in a 'npn transistors' package with 10 or 20 transistors in it.. just in case you have a rat shack near by...
sure , just make a new board, it's a small low parts circuit, probably easier than debugging anyway...
hopefully it will go smoothly and work for you.
let us know. :)
sorry, wasn't quite clear. i was wondering the differences between the original schematic i posted in my first post, compared to the actual lpb-1 booster schematic that was just linked to on this page. but, i was also curious about the differences, if any, that would've arisen from the minor changes i made to the resistor values, so thanks for clearing that up.
oh, ok - yes, i believe they are the same exact circuit.
they aren't exactly the same. Brad's version has an extra resistor and different caps i believe. Unless I drew up his schematic wrong, here are the two side by side:
(http://www.muzique.com/schem/lpb1.gif)(http://img35.imageshack.us/img35/1710/guitarboostschematicbra.png)
well, yeah, (i believe c1 should be .15uf rather than 15uf tho), which IS different than the lpb's .1uf - a minor difference to me, and the extra resistor is a 1m 'pop' prevention resistor, used to leak any dc to ground when wired as true bypass and in bypass... sort of a modern addition, but it's still an lpb.
yup, the 15uf was just a mistake by me making the schematic. so they're more or less just the same circuit aside from the .1uf compared to the .15f? if the .15uf cuts less bass, why would you want a .1uf? i'm trying to keep my tone as unaltered as possible, i just want to drive my amp harder to get better sustain and harmonics.
.1uf vs .15uf ..... they'll still both cut a bit of bass, to prevent the transistor from getting 'flabby' or distorted... so basically, the orig. probably played it safe and used a .1 rather than anything bigger, though a .15 is probably fine... if you felt the circuit was too bassy you could use a .1 as well, but i doubt you'd hear a difference either way.. were talking about (estimating here) rolling off bass 6 db per octave below say 40hz vs say 50hz, both below a guitars low end output either way... it may or may not matter, but if you get a bit of distortion in the low end try the .1 if not don't worry about it.
well unfortunately a case of severe food poisoning has kept me out this weekend, but i plan on rebuilding this soon and reporting back.
Does anyone have any suggestions for cutting the stripboard? I've had some ok success using wire cutters parallel to the copper strips, but I haven't figured out a way to cleanly cut perpendicular to them.
To cut the vero, I score mine deeply with a craft knife then cut it with side cutters
Quote from: cgibsong002 on November 21, 2010, 09:47:02 PM
well unfortunately a case of severe food poisoning has kept me out this weekend, but i plan on rebuilding this soon and reporting back.
Does anyone have any suggestions for cutting the stripboard? I've had some ok success using wire cutters parallel to the copper strips, but I haven't figured out a way to cleanly cut perpendicular to them.
I use a 5 mm drill , a few twists by hand of course , and its gone....watch for tiny burrs though ok...but it removes it nice.,.
*Post removed, because apparently, I can't read :P
- This is a CBE situation, not a DSG.
perfect, thanks guys.
Also, I ran my simulation with a fake 100mV sine wave as the input and a 9.48V DC power source. Some interesting results. (hopefully I put this schematic together correctly)
Circuit with input signal, DC power source, recording the decibel gain from input to output. Additionally, the lower the load resistor on the transistor, the greater the gain. Using a 330 ohm instead of the 390 ohm gave me just under an extra decibel.
(http://img210.imageshack.us/img210/9291/84108519.png)
Then this picture should be what kind of DC readings I should be getting when taking measurements with no input. It appears I should be getting a 6-7V approximate drop across the 10K ohm resistor, with most of the remaining voltage going through the transistor. So it appears like my 10K ohm resistor in my actual circuit is somehow being bypassed since nearly all my voltage is going straight through the transistor.
(http://img843.imageshack.us/img843/4684/dcvoltageswithnoinput.png)
EDIT:
Quote from: MikeH on November 18, 2010, 01:41:18 PM
Measure from each leg (Drain, Gate & Source) to ground. It's explained in the debugging thread, but it might talk about CBE for Collector, Base & Emitter. But the method is the same.
Post those voltages.
I was still in multisim when i noticed you posted that, so I did this real quick. Let me check my actual data now.
(http://img99.imageshack.us/img99/7247/dgandstoground.png)
Now, correct me if I'm wrong here. But I'm getting almost the full input voltage appearing across my transistor, when most of it should be going across the 10K and only a few volts across the transistor. The Drain of the transistor is only connected to the 10K and the .15uF. If I'm getting full voltage across the transistor, it appears my 10K is being bypassed and the power signal is going straight to the .15uF. Now, if you're looking at the stripboard layout rather than the schematic, it would be very obvious that my problem is caused by lack of a cut in the first strip, correct? If there's no cut, the 9 volts would follow least resistance and bypass both of those resistors, go straight to the cap, which will then shoot the full voltage across the transistor.
Does this sound correct?
EDIT again: it appears I'm correct, at least somewhat. I just checked, and I'm getting barely any voltage across the 10K, and over 8 volts across the capacitor. But I can't see how I possibly have a jump in my cut... is there another explanation for this?
EDIT again again (I'm just talking to myself now :D ): GIANT mind@#$%. for me at least. I just re-ran my simulation with a short from power to the .15uF, which would be the same as if my cut was not actually a cut. I achieved results more or less identical to the actual readings I just took. Is there another way there could be a short here even if the strip is properly cut?
triple post... i know, i know, i apologize. but... Problem solved!! mostly.
If you can believe it... we all missed it. The transistor was backwards! I redid the whole circuit board on a new piece of stripboard, and triple checked the cuts and continuities before any soldering. everything was fine, so i redid the circuit. plugged in, and identical results. i got incredibly confused, and figured the only possible thing was the transistor. in multisim, i flipped it around just to check, and what do you know, i got the same results as i did on my actual pedal. i then flipped the transistor, and the pedal works now!
only problem i'm getting is crackling which is only really noticeable through the gain channel. i think it's my pot, the input wire to the pot (output from the circuit), was cutting in and out before. i resoldered it and now it works, but cuts in and out. i've resoldered that connection many times as it kept giving me trouble seemingly. did i possibly burn a connection, or is it maybe just dirty from having solder resin melting and possibly getting inside?
;D :icon_redface: ;D
cool. i'm impressed that you ran a sim, and used it to get 'good' voltage readings to compare to. nice.
and you did it on your own. which is a good feeling.
yeah! i was real happy about all of that. i mean, i ran into way too many difficulties for such a simple circuit, but it was my first one, and i learned a lot from it.
I also really like being able to use the simulation. While I haven't figured it out yet for being able to simulate an effected signal, it's incredibly useful for trouble shooting as it gives me more or less exactly what i should be getting. if i'm not putting a guitar signal in, all i have to do is match my DC supply with my measured DC supply, and i should be getting quite accurate results. definitely a good tool!
now, if you all don't mind, I'm going to start a new topic on how to modify this circuit... it's not quite what I was expecting :icon_lol: no.. but seriously ;D oh well, live and learn
Oh, so you triple checked the transistor pinout and it worked? Wow, if only someone had suggested that days ago :icon_rolleyes:
a lot of people have done that on accident so don't feel bad. Whenever i'm building something with transistors i use a multimeter to confirm the transistor pinout. You can get cheap meters that have a little socket to test transistors, and they have the orientation marked on the socket. If you plug it in the wrong way it won't read, so once you get an HFE reading you know which legs are which. added bonus of having a way to get your gain reading at the same time :) I picked up my meter for $10 at an electronics store. I don't trust it for other readings, but for identifying the pinout on your transistor it works fine. It's easier for me than sifting through pages of transistor infosheets or doing a google search.
Quote from: Cardboard Tube Samurai on November 23, 2010, 06:42:26 AM
Oh, so you triple checked the transistor pinout and it worked? Wow, if only someone had suggested that days ago :icon_rolleyes:
don't roll your eyes at me dude, I'm the new one here, I posted pictures, and no one else noticed it either. I have no reason to feel bad or stupid for messing that up. I've never used a stripboard layout schematic before, and to my perspective, I was 100% positive that I had the transistor in correctly according to schematic. It was a misunderstanding with how to read the layout.
I really appreciate everyones help. I ended up learning a lot through this project, and I actually learned much, much more due to it not functioning correctly. Because of that, I learned how to properly simulate my circuits in software so that in the future I can trouble shoot much more easily and learn how things work
thanks :)
Hey don't get me wrong, I'm not saying you should feel "bad or stupid for messing that up". Don't put words in my mouth. Just saying, don't go discounting or brushing off advice people give here. There were a few of us who suggested checking the pinout of transistor but you insisted that it looked right, based on the diagram. I too have done this before and know how easy it is to do. Truth be told, I've only been at this a few years and have asked plenty of similar questions and I've only recently over the last year or so been able to actually provide insight to "noob" questions. Fact is, most of us have been there before and can offer these suggestions based on experience. Sometimes though, it's not a great deal harder to just desolder the thing and turn it around or to look up a pinout diagram on the net and this approach will save you a lot of headaches. +1 on the advice of a cheap meter that can test transistors: I have one of these handy at my bench too.
Quote from: Cardboard Tube Samurai on November 23, 2010, 03:56:29 PM
Hey don't get me wrong, I'm not saying you should feel "bad or stupid for messing that up". Don't put words in my mouth. Just saying, don't go discounting or brushing off advice people give here. There were a few of us who suggested checking the pinout of transistor but you insisted that it looked right, based on the diagram. I too have done this before and know how easy it is to do. Truth be told, I've only been at this a few years and have asked plenty of similar questions and I've only recently over the last year or so been able to actually provide insight to "noob" questions. Fact is, most of us have been there before and can offer these suggestions based on experience. Sometimes though, it's not a great deal harder to just desolder the thing and turn it around or to look up a pinout diagram on the net and this approach will save you a lot of headaches. +1 on the advice of a cheap meter that can test transistors: I have one of these handy at my bench too.
Yeah dude, I fully understand what you're saying. But when you're frustrated and there's a lot of possible things to look at, you miss things. I didn't discount the advice... I didn't have a schematic that I was going off of. I looked up the pinout, but then realized the pinout does nothing for me without a schematic. So it wasn't that i discounted the advice, it was just a mistake on my part. In fact it was that advice that in the end gave me the idea to flip the tranny in the schematic and realize the mistake.
So is this the part where we hug? :P
(http://3.bp.blogspot.com/_oOdRKt65AxI/SiAhaSAbveI/AAAAAAAAAcE/NroMCngTUDg/s400/hug__by_Defies.jpg)
Quote from: MikeH on November 15, 2010, 11:20:56 PM
Also double check the pinout of your transistor.
Thats what I meant by this. FYI taking proper voltages can show you that you transistor is backwards. In the future I'd recommend posting the voltages using the method described in the "DEBUGGING" sticky thread. Mist people around here wont even offer any help if you haven't posted the checklist from that thread.