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Topics - croquet hoop

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1
Open Discussion / Bourns potentiometers?
« on: December 06, 2013, 03:36:43 AM »
I noticed that Mouser sells Bourns 9mm pots (search for 652-PTD90) for a rather decent price ($1.7). Has anyone tried them? I am wondering if I should give them a chance, or just place another order at Tayda just for pots and forget about them.

http://fr.mouser.com/Passive-Components/Potentiometers-Trimmers-Rheostats/Potentiometers/_/N-9q0ypZscv7?P=1yzshlv&Keyword=652-PTD90&Ns=Resistance|0&FS=True

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Open Discussion / Polarized cap orientation
« on: November 25, 2013, 10:26:19 PM »
I was observing the decimator schematic and it looks like one electro capacitor is implemented in reverse in the circuit:



Does the orientation of this cap serves a specific purpose? I know that it is generally safe to replace a polarized cap with a non-polarized one, but does this still apply in this case? (MLCC caps are so much practical than electro caps in small builds)

3
General Questions / Road Rage on a switch
« on: November 03, 2013, 03:30:14 PM »
If I want to select between 9 and 18 V with a switch, can I do it like this, with just a SPDT?


4
Open Discussion / Short pin headers
« on: November 02, 2013, 11:22:47 AM »
Since we've been talking about it in Gledison's thread, I was wondering... is there such a thing as short/low profile pin header? I'm talking about this part (the female connector):



But those are around 8 mm high, and I'd like them to be ~4 mm instead. A quick search at mouser did not yield any results. Anybody knows whether such shorter connectors exist, and where to find them?

5
Open Discussion / What do you guys do...
« on: October 29, 2013, 01:36:51 PM »
... when everything goes FUBAR?

It started with a batch of slightly off-spec boards from OSH Park. Rows of holes were drilled too small, so the pin headers that were meant to fit in do not (they did on a previous batch with the same specs). So I'll have to spend time fixing something designed to save time. Great  8)

Then I had to debug a big muff build, so I built a small signal generator on perf, but the thing would only emit an audible signal when I touched it (just about anywhere, in no precise spot it was quite tolerant in its own way). After an hour or so I got it to work as expected, and given the time spent on such a trivial build I should have known better and stopped there, but nevertheless I figured I'd add it inside my test rig with a SPDT to switch between guitar input and signal generator and then add an audio probe (which is the only thing I should have cared about). I won't describe what happened exactly during the following three hours, because I don't really want to re-live the thing, but I ended up with a less functional testing rig, an infuriated mind and of course no debugged big muff.

Now I've put away everything and cooled down, and I'm a bit sorry for the rant but it felt good to write this. Do this kind of crap often happen to you? I mean, I've stumbled here and there while making my first fews builds, and it was perfectly expected, but come on four hours (with a few pauses) on something that simple, for this  kind of results... pretty depressing.

6
Tech Help - Projects Page / Big Muff troubleshooting
« on: October 28, 2013, 04:33:40 PM »
I'm having some trouble with a Big Muff I am building (Spasm Chasm specs, Spasm Chasm pcb from CJ) . The most obvious problems are that the pedal sounds weak and muffled, and the sustain pot doubles as a volume knob when you turn it down, the gain decreases, but so does volumes too. At half the rotation, there is almost no sound passing.

I double checked the values when populating the board, I have checked them again, they seem alright.
I tested with the transistors reversed, and with different transistor types (2N5088, 2n5099, BC550C, MPSA18), no difference whatsoever.
I let it rest for two days.
I re-did the wiring on the vol and sus pots. No change either.

Here are the voltages:

Battery : 8.70v

Q1:

E= 0.05
B= 0.64
C= 3.90

Q2:

E= 0.06
B= 0.63
C= 6.05

Q3:

E= 0.72
B= 1.09
C= 6.70

Q4:

E= 0.89
B= 1.37
C= 4.23

I compared them to those taken on a working P19 build, they are not terribly far apart, so I don't think the problem lies here. I have checked the solder points and that seems OK too, although it's utterly impractical to check due to the board mounted pots.

I think that the most telling symptom is the behaviour of the sustain pot, but I have no idea what to infer from there. Does anybody have an idea?

7
Open Discussion / Box cap tolerance
« on: October 11, 2013, 07:38:42 AM »
I noticed that musikding has good prices on Wima box caps, so I added a few of them to my last order. However, it turns out that they are 10% tolerance, instead of the usual 5% tolerance generally recommended. Are there instances where the 5% tolerance would really be critical? Or should I not bother and use them indifferently?

8
Build Reports / Lunar Module
« on: September 17, 2013, 06:46:03 AM »
After a few weeks playing with spiders (boards with pots, jacks & switches wired outside boxes), it was high time I started boxing stuff. So here is my first complete build, a Lunar Module in a 1590B. I thought the size of the box would make things easier but I did not realize that the more knobs, the more trouble... now I really understand why so many love board-mounted pots.

The board is from Pickdropper, the enclosure from ColesBD. No labels, as it's easy to remember what each pot does and I really love the understated look of the pedal. Likewise, I added a trimmer to the 3PDT board, but I ended up not using a led for the same reason (and it's a fuzz, I'll know when it's on). So I left the LED conector (at the bottom) empty. In the end I could just have used a DPDT, which I would have preferred since I really don't like the clunky feel of 3PDT switches, but hey. I'll probably replace the switch with an opto-tron board from Josh soon.





All in all, a great learning experience, despite (or because) a few bumps in the road. Now, the next builds are all intended to go in 1590A boxes, but maybe I'll start with 2-knobs effects this time  ;D

9
Open Discussion / DIY power supply
« on: August 25, 2013, 08:13:59 AM »
I would like to build a power supply for my pedalboard, but I'd rather avoid messing with 220v. So I've come to think that something like that could be interesting (basically, a row of 7809 voltage regulators fed by a 12-19 V switching power supply). What can I expect from such a design (compared to the ubiquitous 1Spot for instance)? Do you see any major reason I should stay away from it and choose something else?

10
Open Discussion / Alpha momentary DPDT Stomp
« on: August 14, 2013, 06:22:30 AM »
Has anyone ever used them ? http://www.smallbearelec.com/servlet/Detail?no=1256

I'm wondering how they feel. I have a few of the latching version and the shorter travel before the click is not a problem to me, but I'd like to be sure that, as a momentary stomp, they do not click and have a nice action.

The reason I ask is that they're still less expensive than a 3PDT switch, they have a smaller body than the common no-name SPST momentary stomp switch, and I expect them to be more reliable than both.

So, has anyone tried them?

11
General Questions / Fool-proof LED testing & min CLR value
« on: July 28, 2013, 10:31:55 AM »
I've just put together a small LED tester on vero, with the possibility to use two in series and a B10k pot to find the right CLR value. Nothing groundbreaking, but it should save me time on future builds (I have a bunch of circuits I still need to box).



Now I'd like to make it as foolproof as possible and add a resistor to avoid burning LEDs when I turn the pot to the left, but I don't really know which value to choose, and where to add the resistor. Any idea? I've done a quick search but I don't think I found what I wanted.


12
Open Discussion / Testing Ge diodes
« on: July 24, 2013, 01:18:46 PM »
I know the subject of Ge diodes has been beaten to death, but I'd like to be sure of one or two things. First of all, I bought 1n34a and 1n270 diodes from Tayda on two separate orders (one month apart), 5 of each each time, and I've just taken the time to test them with the diode setting of my DMM, with varying results:

- 1st batch of 1n34a: nothing, continuity test fails, the things seem to be dead, not even useful as jumpers
- 2nd batch of 1n34a: the DMM indicates values around 330, so I guess it's in line with the expected .3v drop.

- 1st batch of 1n270: same here, values are between 300-350
- 2nd batch of 1n270: the values are around 700 this time; silicon diode in a glass package?

Now I'm wondering if the diodes that seem to be proper Ge are really what they look like, or if there's something fishy with them as well. I know that the fv is supposed to rise under the heat of a finger, can anyone tell me more about this test (how long do I have to heat the diode before I see the fv rise, and in which proportions is it supposed to increase?)

Additionally, can anyone recommend reliable sellers for Ge diodes? (I've just received 1n34as from Banzai as well, the readings are all over the place, between .35 and .56... is this to be expected?) Preferably European sellers, I'd rather not wait three more weeks before I get usable 1n34as.

13
Open Discussion / Not so big 1 uF box caps?
« on: June 20, 2013, 05:07:59 AM »
I received my first Tayda order yesterday (yay!) and everything looks good so far, except that their 1 uF box caps are waaaaay too big:



No complaint, the specs were written on the website, that's why I only ordered a few. But since I need them for several mini builds, I'd rather use some that are the size of the yellow one (which I got in a Tiny Giant kit, so I didn't source it myself). I know, X7R MLCCs and tants are the way to go when space is tight, but many baby layouts have space for box caps, so why not?

So, do you have any recommendation? I have a cart at mouser so I looked at a few datasheets for 63v 1 uF caps (Kemet R82 and MMKs, Epcos) but I'm not sure I can find anything the same size as the mysterious yellow cap.

14
General Questions / Mudbunny mid pot
« on: June 15, 2013, 11:43:06 AM »
I have searched but found no answer on the forum: is there a reason for the disappearance of the mid pot on the last version of the Mudbunny?

15
General Questions / First order, anything missing?
« on: April 30, 2013, 10:01:17 AM »
Hi everyone,

After many hours of reading here and at diystompboxes, I am ready to dive into the depths of DIY pedals. I have checked everything twice, but I would like to be sure I did not overlook anything crucial. I will begin with the following projects :

Cupcake (madbean pcb)
Afterlife (madbean pcb)
Bosstone (vero)
Transistor tester (perf)

And once I am sure I know what I'm doing:
Engineer's thumb (jmk pcb)
Moon Lander (jmk pcb)

Basically, I'll order 40-80 resistors and 20-30 caps of each necessary value, 3 to 5 times the ICs, transistors and diodes needed (to have parts on hand when I decide to make variations, or to have spares in case some parts are faulty). And 3x the pots I need and a number of knobs.

Plus, for each pedal:
- enclosure
- 3PDT switch
- 2.1mm power jack
- LED bezel
- lots of LEDs (cheap and always useful)
- 2x mono jacks

Plus a bunch of sockets, vero board, perf board, and 24 awg stranded wire in different colors. Am I overlooking anything?

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