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Messages - RobA

#31
Small Bear has the Cool Audio V2164 in stock. It's a bit price at $3.95, although, that's not too bad for four of them in one package.
#32
The 2164 is obsolete completely I think. Cool Audio also makes a 2162. Given the Behringer synth rumors running around and now being teased constantly by Behringer themselves, it could be that we'll be seeing some more VCA stuff out of Cool Audio too.

Edit: I just checked Cool Audio's site and they list the V2164 also. So, maybe they are available from them.

http://www.coolaudio.com/docs/datasheet/COOLAUDIO_V2164MD_DATASHEET.pdf
#33
With the WIMA caps the FKS and FKP caps are also good for pedals. The FKP are actually very good. They are different sizes. All of the WIMA caps sizes depend on the series (3 versus 2 versus 02 and MKS, FKP, etc.) and voltage ratings of the caps. So, you need to look at the spec sheet to be sure you are getting the right ones (5mm lead spacing and not too huge). You should be able to get the MKS caps down to about 1n I think.

On the sizes, most PCB's are designed to take into account the need for more space with increasing capacitance, but if you start mixing in larger voltage rating at bigger capacitances, it probably won't fit. High voltage rating at lower capacitance for the WIMA caps is usually fine. The FKP 2 caps can get big. I have some 47pF FKP 2 caps that are nearly as big as the MKS 2 1µF 63V caps. Most PCB's won't have room for that 47pF cap.

Another choice in the smaller values is to go with a C0G MLCC cap. If you get the 5mm lead spacing variety they will fit fine. 
#34
It should be fine as long as you've wired it to match. A loud hum always makes me suspicious of a ground issue somewhere. I'd start by checking all the ground continuity first.
#35
Check the polarity on the EHX power supply. Some of them have center positive outputs.
#36
Open Discussion / Re: Remastered classics
February 28, 2015, 07:46:25 PM
I stumbled on the Cannibal Corpse one earlier and thought it was hilarious. The Bob Marley "Is this Love" was actually pretty good. The funniest bit though was the title for Rage Against the Machine's Killing in the Name.
#37
Open Discussion / Re: Volume Meter Build
February 27, 2015, 01:38:04 AM
This would be really easy to do using an MCU. If you don't want to go the MCU way, there's the LM391x series that is in that last link that Dan provided. The LM3915 is the dB scale version. Here's a link to an Intstructables project that uses the IC, http://www.instructables.com/id/LM3915LM3916-VU-Meter/

It would take a bit of scaling for the voltages to be right, but the project looks pretty easy overall.
#38
Am I missing something? It looks to me like it's pretty much a wave shaper that depends on the amplitude of the input to get the output waveform. It would need to be embedded in some gain sections to do anything with the normal voltage levels from a pickup.

I simulated it in LTSpice and I had to put some pretty big gain on a pregain stage to get it to do anything with guitar pickup input voltage levels. Then the output curve is still pretty much a static response that depends heavily on the input voltage and very much on the output load.

It reminds me of doing static wave shaping in digital. The problem there is that this doesn't lend itself very well to any kind of natural tubelike response. Maybe this could be made to work well, but I think it would take a ton of signal conditioning before and after to get any sort of natural response. 
#39
Open Discussion / Re: Why did you start building?
February 25, 2015, 05:56:49 PM
My intention when I started was just to learn about what made analog effects work so that I could do  more with the digital effects I was writing. I spent about a year doing nothing but breadboarding before I finally realized that the Fuzz Face circuit I'd been messing with really did sound amazing enough that I should put it in a box so that I could actually use it to play with. I did that first one point-to-point on hole board and pretty much had to learn to solder to do it.

I then decided to build the one effect that I had in my youth and sold and wished I hadn't, the CE-2. I did that on a Tonepad layout but eventually got annoyed enough with how noisy it was that I wanted to redo it. That's how I discovered Madbean.

My main goal is still learning about how the analog stuff works so I can do it in digital, but I now have so many pedals built that I'm kinda stunned by it every time I stop and look in the drawer that most of them sit in. The majority of them are the classic circuits that just aren't really obtainable any other way, so that's really cool too.
#40
The first LM78L05 data sheet linked earlier in the conversation is completely confusing and the L78L05 figure caption is also not as clear as it would be if they just put the view right by each of the  diagrams. I really don't get why those are done they way they are. At least the new TI doc is clear and has a good depiction of the part now. I'm guessing they went to the 3D diagram because they've had complaints about the old data sheet.

Anyway, I'm just trying to be sure that I'm giving the right advice that these two should have the same pinout.
#41
Quote from: mgwhit on February 24, 2015, 02:16:48 AM
Holy crap!  I just remembered working on a prototype PCB from jimmybjj a few years ago where i "discovered" that the proper voltage regulator orientation was backwards to his silkscreen.  He was 100% sure that his other board worked with the regulator oriented according to the silkscreen, but couldn't check because he had already lent it out.  Can you see where this is going?

Yeah, I just checked.  His build parts list specified LM78L05.  All my parts orders from around that period of time were L78L05s.  I owe him an apology!

I'm still seeing the pinouts of the two as being the same. Here's the two spec sheets from the parts at Mouser,
LM78L05, http://www.mouser.com/ds/2/149/LM78L05A-195676.pdf
L78L05, http://www.st.com/web/en/resource/technical/document/datasheet/CD00000446.pdf
#42
Open Discussion / Re: Store bought Multi-effects
February 24, 2015, 12:40:39 AM
Quote from: GermanCdn on February 23, 2015, 09:33:06 PM
(putting on my aluminum foil suit and pretending I don't DIY)

I always found the Vox Valvetronix multi unit to be a pretty good sounding little unit, bunch of decent amp and pedal sims, expression pedal, etc.  And it was dirt cheap.  Only thing I didn't like about it was it's convoluted stomping arrangement, which I'm pretty sure you can MIDI around.

(taking off aluminum foil suit)

PREPARE THE STAKE!  HE'S A WITCH!
I agree completely. The best thing about them for me was that they have the least impact on the dynamics of my playing of any of the sims I've played with. The worst thing was the way I'd have to handle the switching on it. I did have one of the smaller units where this issue is worse, but I figured that the only way to handle switching of effects and stuff would be to program in a sequence of presets that would go through an entire performance.

They aren't perfect by any measure, but they are usable and convenient and pretty cheap.
#43
Build Reports / Re: Rob A's Hyperbolic Fuzz
February 23, 2015, 08:08:22 PM
The finish really is gorgeous and so deliciously purple. Thanks so much for making your vero layout of this available too. I really appreciate it.

Rob
#44
Quote from: bigdaddymrx on February 23, 2015, 12:38:23 AM
Would I still orient the L78L05 on the pcb the same way the LM78L05 would go?
Yeah. If you look at the schematic, the output pin of the regulator hooks to the +pin of C29 and pin 1 of the PT2399. Then you look to the layout with the traces on it. With the regulator rotated 180° to what you had on your breadboard, that puts the right hand pin being the output. If I recall correctly, that's matches what you had.

The best way to handle this situation is to socket the PT2399 and power the board up without the PT2399 in place, then you can measure the voltage at pin 1 of the socket before you put the PT2399 in there. You should socket the PT2399 anyway because some of them are really noisy and you end up needing to change them out for a new one anyway.

The J112 looks to just drive the phaser LFO indicator LED. You could build the circuit and socket that transistor and try different JFET's in there. It looks to me like the phaser would work fine without the J112 in there at all. You just wouldn't have the LED rate indicator until you got one in there that worked.
#45
Yikes! That's a beast of a build to go after as a second build.

I haven't built a Laserwolf yet. I just checked the layout for the PCB and your regulator looks fine. It's for getting the 5V for the PT2399 and the PT2399 can handle up to 5.5V fine. The absolute max on the PT2399 is actually 6.5V. So your regulator is well within the limits for this build.

I'm looking at the J112 now to see if I can figure out if it's sub-able. Of course, Brian can answer that question better.