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I got an ad from MCM for these this morning, http://www.mcmelectronics.com/manufacturer/EXCELITAS-TECH/01000312. Since they are made by the same place that makes the vactrols, I thought they might be OK. Price is pretty good if they are good.

Anyone seen these around anywhere?
https://www.sparkfun.com/videos#all/sYSxy4lUOEo/67

They seem to be new clones of the seven segment displays from old HP calculators. Unfortunately, Sparkfun is already out of stock on them. I can't find them at Mouser.

Are there any layout templates around for pedals with lots of pots/switches? I've got some templates for two, three, up to around six knobs or switches, but I haven't seen anything with guides for bigger control layouts. I'm starting to layout an effect with seven knobs and three toggle switches and I'd like to board mount them. I think I can do a layout for a 1590BB with two rows of 5 using 9mm pots, but that's getting a bit tight.

Anyone try the upgraded service from Seeed yet? It looks like it supports V grooves and some panelization now. They don't have the pricing online though, so you have to set the order up through email. It's supposed to include better screen printing too. It could be cost effective for combos of smaller boards but I can't really tell at this point.

I've been working on a circuit where I used the LM3046 and decided I wanted to try it out using regular old transistors, so I needed to match some. I found this doc on line describing a pretty slick technique. I tried it out and it seems to have worked well. Here's the link https://home.comcast.net/~ijfritz/MiscProj/transmat001.pdf. So, I was wondering if anyone here had used this process or had suggestions for different methods?

I'm doing a layout for a new effect that has 2 pots and 4 switches; Gain and Vol and Treble Boost, Fuzz, Octave, and Tone and I want to board mount them using 9mm pots and standard toggles in a 125B. So, here are the questions. First, assuming that no other parts are in the way and there is just the added depth of the PCB, is there enough room left to top mount the jacks in a 125B? How about if I went to a 1590BB instead. I'm doubting it in the 1590BB because top mounting in those things is tight already. The second question is how would you layout that set of controls? I was thinking the two knobs on top and then the four toggles on a row below that. That seems a bit weird though and unbalanced, but the two knobs and one switch on one row with three toggles below doesn't seem right either.

New code to Feb. 12

Anyone know a source for the transformers that are in the EHX tube based pedals. The ones that do 12VAC input to something over 200VAC. I think Smallbear used to have them, but I can't find them now. Something similar would do the job too, but these looked to be really convenient.

The course is called "Fundamentals of Audio and Music Engineering: Part 1 Musical Sound & Electronics" and lasts six weeks starting on Feb. 3rd. I don't know anything about the course past what's listed on the web page (https://www.coursera.org/course/audiomusicengpart1), but the syllabus looks interesting and relevant to the interests of folks around here. This is the syllabus:

Week 1

Lesson 1: Introduction to oscillations and sound waves, simple oscillating systems, sound pressure, sound waves, the speed of sound, wavelength, frequency and pitch, sound pressure level, loudness, making sound, properties of musical sound versus "noise"

Lesson 2: Electronics fundamentals - charge, current, voltage, power, resistance, Ohm's law, DC circuits, finding currents and voltages in simple circuits

Week 2

Lesson 1: Reflection and absorption of sound, resonances in air columns, resonances in enclosures and rooms, diffraction and diffusion of sound, reverberation, principles of designing a good music studio

Lesson 2:  AC signals, phase and complex numbers, capacitors, inductors, transformers, impedance, AC circuits and AC circuit analysis, simple filters (high-pass, low-pass, band-pass)

Week 3

Lesson 1: Transistors, vacuum tubes, opamps, amplification, power gain, single-stage amplifiers

Lesson 2: Converting sound to electrical signals –microphones and guitar pickups, converting electrical signals to sound – loudspeakers   

Week 4 

Lesson 1: Electric guitar electronics, pickup design, pickup placement and tone, volume control circuits, tone control circuits

Lesson 2:  Overview of a simple guitar amplifier, power supply, volume control, preamp, tone control, power amp section

Week 5

Lesson 1: Designing speaker enclosures, basic principles, interaction of speaker driver with the cabinet, why a cabinet at all?

Lesson 2: Speaker designs for home stereo, crossover networks, guitar amplifier (open) speaker enclosures, bass amplifier (closed and vented) speaker enclosures

Week 6

Lesson 1:  Building the guitar amplifier, how to solder, getting the amp to work - systematic testing and troubleshooting

Lesson 2: Visualizing sound waves, frequency content and tone, signal modification in electro-acoustic systems, tube amplifiers and distortion, wah pedal, talk box

I'm going to do some etching today, so I figured it would be fun to throw in a totally over-the-top fuzz. So, which one? (I've already put a Zombii and a Cosmo into the etch list.)

Anyone know what the Boss Dyna Drive, DN-2 is? Musicians Friend has them on their SDoD for $30 and I haven't seen on before. Is it part of a tube amp simulation circuit? Digital?

I was just wondering if anyone has tried these out
http://www.nxp.com/documents/data_sheet/PMBFJ620.pdf

They are a pair of JFET's on a single SMD device. I picked some up at Mouser in my last order in the hope that they might be pretty closely matched as a pair. They are a pain to test because they are really small SOT-363 packages, so I've only tested two of them that I put on adapter boards. But, the two pairs I've tested have been dead on in both Idss and Vgs-off. I'm going to breadboard a couple of phase45 sections to test them in first, but I'd like to hear if anyone has any experience with them.

Has anyone tried one of this? What did you think?
http://www.pedaltrain.com/products/power/volto.php

I'm doing some playing with various power supply generation IC's and I'd like to test them in some of the worst known offenders for being sensitive to power supplies. I'm looking at 9V, -9V, +/-9V, 15V, and 18V type circuits.

I've already dropped one IC from consideration just using a Ge negative rail fuzz, but a couple of other IC's have done brilliantly with it. So, I need to throw some harder cases at them. Any suggestions?

Linear Technology has released a version of LTSpice for OS X. I just downloaded it and started playing with it so I don't know yet what works and what doesn't. It's a very minimal interface at this point, but I have run a couple of simulations on it and it is working. Not bad timing either since Wine is now broken on my machine and I couldn't run LTspice under Wine anymore.

http://www.linear.com/designtools/software/

I've been mucking about with the LM3900 op amp to see what I could do with it and came across an interesting potential application for it in a pedal context. On page forty of the app note http://www.ti.com/lit/an/snoa653/snoa653.pdf, there's a circuit for using it as an audio mixer. The kinda interesting thing is that it has a switching mechanism on each channel of the mixer that can be used to mute the channel. I figured that this could be used to do buffered bypass switching so I tried it using a transistor for the switching and it works. There's another example circuit in there somewhere that shows how to use two of the op amps to setup a flip-flop circuit too. I haven't tried that part, but since there are four op amps on the IC, it might be possible to set up a flip-flop and the two switched sections using one LM3900.

I don't think that I'll be looking into this myself because I'm now pretty satisfied with using either the NJM2121 or a double latched relay for switching if I need something other than a 3PDT. But, I figured somebody else might want to play with it as a potential solution, so I figured I'd pass it along.

Assuming that pots and switches aren't board mounted and that there are two pots and one SPST switch, how small does a board need to be to be practical for a 1590A build?

I got an email from Digi-Key that has what seems to be a new part that could be useful for generating -9V from an input 9V DC. I was wondering if anyone has tried them. Key points are that they are basically an LM78xx voltage regulator (3 pin) but more efficient and if you wire the common and output connections in reverse, it generates a negative voltage! One big feature for us would be that the switching frequency is at ~300kHz. The only place I can find them in the US is Digi-Key and Future Electronics at about $5.

Here's a link,
http://www.cui.com/product/resource/p7805-s.pdf

I can imagine that this has already come up but I haven't found anything by searching. If this has been discussed before, please point me to a thread.

I've been working on laying out some PCB's and considering the pro's and con's of PCB mounted pots and switches and part of what keeps coming up in my head is consideration of box size since using PCB mounted kinda makes this decision for people. Also, top mounted versus side mounted jacks gets involved in this question too. And multi-pedal builds, and ... 

Anyway, the question is, how do you decide on an enclosure size? Do you have a rule like 2 pots in this size, 4 pots 2 switches in this size, etc? I really like the 125B size for things that will fit because I like top mounted jacks. But, I see lots of people using 1590B's and setting up for PCB mounted pots on the 125B can conflict with leaving enough room for side mounted jacks on  1590B's. Etc.

As the result of another discussion here, I've designed a distortion/overdrive on breadboard. I like the results enough and it's different enough that I'm laying out a board for it that I'm considering making available/selling. The circuit would probably benefit from using board mounted pots and this brings up a question that I've been thinking about. I prefer the 9mm pots like these http://www.taydaelectronics.com/10k-ohm-linear-taper-potentiometer-round-shaft-pcb-9mm.html and now that they are more widely available it seems reasonable to use them. But this kinda runs against the norm of using the 16mm Alpha PCB pin pots. So, this brings up the question would using using the 9mm pots bother anyone too much? Is there anything that really puts people off about using them? Any other points or opinions?