The Bazz Fuss is one of the best beginner projects out there (it was maybe my second or third build). Maybe too simple to need a PCB layout, but hey, I had time on my hands. The layout is for the deluxe version from home-wrecker.com, including the transformer. The layout allows you to skip the transformer, if you don’t feel the need. Lood guck with it.

I happened to notice a thread on diystompboxes.com started by Aron about Joe Davisson’s JFET Vulcan. You can listen to some mp3 clips that Aron posted in that thread. I had a layout for the BJT Vulcan from several years back so I decided to update it and convert it to the JFET version. This layout has not been verified yet, but I am confident that it is correct. If you do verify it, please let me know. You should be able to fit it into a Hammond 1590B enclosure.

Note that no power supply filter is included. Depending on your power source, you may want to add one. And the output comes from the middle lug of the LEVEL pot.

You may want to breadboard your build first in order to get the bias right for the JFETs. Choose values for the three 100K resistors that give you JFET drain voltages of 4.5V to 5V. Also, check out Joe’s notes about component values for higher gain.

Plugs

Here are two artifically coloured 1/4″ phone plugs, mono above and stereo below. The green part is called the sleeve and the red part is called the tip. The stereo plug has an additional part (silver in this figure) called the ring. The tip, ring, and sleeve are all insulated from each other and can be used for different purposes. Stereo plugs are sometimes labeled TRS, the initials of Tip, Ring, and Sleeve.

Guitar cables generally have mono plugs where the tip carries the audio signal and the sleeve connects to ground. Stereo plugs appear on headphone cables. If you put a mono plug into a stereo headphone jack, the silver part is replaced by the grounded sleeve and one channel is grounded and, hence, silent. Because the Ring usually carries the Right channel, the right channel is typically silenced.

Jacks

These colourful images represent three panel mount Switchcraft jacks:

• mono (Switchcraft no. 11 on the left),
• stereo (Switchcraft no. 12B in the middle), and
• mono with NC (or normally closed) switch (Switchcraft 12A on the right).

Following the colour scheme above, I have made the sleeve connection green and the tip connection red.

The role of the silver part in this figure depends on the jack. For the (middle) stereo jack, the ring connection is silver. For the (right-hand) mono with NC switch, the shunt for the switch is silver.

Each part of the jack has a solder lug where wires are usually connected. The tip lug is not always located in the same place. Other manufacturers than Switchcraft may use a completely different configuration of the solder lugs for each of these jacks. You can use the contintuity test of your DMM to figure out which lug goes with each plug connector. Alternatively, you can figure this out visually.

These jacks are constructed in layers, with a single piece of metal comprising the lugs and the plug connectors. I have never taken one apart, but there must be some sort of insulation that separates these metal layers from the barrel that contacts the sleeve. So you can just look from the side and see which lugs and connectors are paired.

Schematic symbols for these three jacks often look like these. Layout symbols are similar.

Connections

Often mono plugs are mated to mono jacks and stereo plugs are mated to stereo jacks as shown above. Notice the position of the tip connection. The “click” that you feel when you plug into your guitar, stompbox, or amp is the (red) metal tab that contacts the tip snapping into the groove around the tip. This holds the plug firmly in place until you pull it out. After repeated use, jacks must be replaced when metal fatigue occurs and the jack no longer grips the tip tightly.

Also, compare the mono and stereo arrangements and you will see how a separate connection is made by the ring of the stereo plug touching only the silver metal tab of the stereo jack. Below we will discuss a case where such a separate connection is not desired.

When inserting a 1/4″ phone plug into these jacks, the tip first contacts the grounded socket before reaching the tip connection at the end of its travel. The sleeve connection comes later. This initial contact between tip and ground without a grounded sleeve causes the pops and hum one hears as a cable connected to an on-line amp is plugged into a guitar.

The figure above shows how the mono jack with NC switch has a tip connection that is closed without a plug and open when a plug is inserted. This is useful in stompboxes like Sean MacLennan’s B Blender. His circuit provides an “effects loop” that is blended with the input signal. By using mono jacks with NC switches for the effects loop, a default connection is possible through the shunt lugs when nothing is plugged into the loop jacks.

This figure illustrates how a stereo jack is used as the input jack for a stompbox to switch the ground connection of a battery. The plug is, of course, a mono plug. The ring part of the jack touches the sleeve of the mono plug. If the sleeve part of the jack is grounded as usual, then the mono plug grounds the ring connection. Without a plug, the ring connection is floating.

So the battery’s negative terminal is wired to the ring solder lug of the stereo jack. When there is a mono plug in the jack, the negative battery terminal is grounded and electrons flow. Without the plug, the ground connection is broken. In this way, the battery is disconnected whenever the stompbox is not in use.

Other Jacks

There are more elaborate jacks than these three. There are jacks with more rings, with more NC switches, and also with NO (normally open) switches. For examples, see the Switchcraft link listed below. Although these exotic jacks do not usually find their way into stompboxes, you will certainly encounter them in guitar amplifiers.

The illustrations above picture “open frame” metal jacks.  There are also panel mount jacks that enclose the plug connections inside a plastic box. For example, see these Switchcraft jacks.  Such jacks are often used to insulate the sleeve connection from the enclosure. This can also be accomplished with open frame metal jacks using nylon washers.

PCB mount jacks offer another possibility. These are also enclosed and quite compact. For an example of their application, see the design described in A Nice Design for 1590B Enclosures.

References and Additional Resources

1. Neutrik Jacks
2. Switchcraft Phone Jacks
3. Wikipedia: TRS Connector

Nordic sent us a revision of the gaussmarkov.net Big Muff Pi Triangle layout. He added his own artistic touches and created something that differs from most of our layouts in several ways.

First of all, you may notice all the round corners. These are produced with the same Eagle MITER command as the diagonal corners that you usually see on this site. But you have to switch the shape of the miter. Nordic also added this flourish to T intersections using the Eagle SPLIT command. These are a bit of extra work but they look great.

Second, Nordic lined everything up in straighter rows. When he did this, Nordic also adjusted the box capacitors (with a 100mil lead spacing) so that the boxes are centered along with the resistors. Most gaussmarkov.net layouts tend to keep the pads lined up in rows so that the capacitors’ boxes are off-center.

Third, Nordic rearranged some components to remove a jumper. Whether you consider jumpers inelegant or not is largely a matter of taste. The need for them generally depends on how compact your layout must be. Used appropriately, jumpers do not introduce electronic issues. They are, after all, just resistors with 0K resistance and resistors are all over the place.

When I looked at Nordic’s changes, I noticed a couple of other improvements myself and Nordic let me add them. For example, the transistors are lined up more neatly. I also decided to hook up C11, which is part of the tone stack, to +9V instead of ground. As you can see, it’s awkward to get a ground connection to C11 given the overall layout. Because capacitors block DC, hooking up a capacitor to any constant voltage amounts to the same thing for the effects on the signal.

Now some of these changes require a larger board. Does that matter? Not in this case, as you can see below, Nordic’s revision fits in a 1590B. You can see an example by stobiepole of an actual build like that using the original layout in this post.

If you would like to use the Eagle files for this layout, there in this zip file.

A basic goal of gaussmarkov.net is to provide support for designing your own build. Not only can you get PCB images, but you can also get Eagle CAD files for those images that you can rework. Because the PCB design is already verified, you can be confident that your version is going to work also.

This post is the first of a series that will offer projects by others that are based in part on gaussmarkov.net projects. George Collier took the Thor circuit from runoffgroove.com, the Eagle files from gaussmarkov.net, and put in his own 3 band active tone control. Here’s a gut shot of his build. If you view the image in another browser window, you can see it full size.

George is using his Thor as a preamp in an amp he built and calls the Tone Reaper. “I also attached a shot of the cabinet the preamp is housed in. It’s been rebuilt a few times now to implement some changes since it was first built in 2007. It’s a totally different animal now! I’m using the the Thor with the tone control as a preamp, feeding an LM3875 amp. The cabinet is open back and has a single Eminence 12″ Texas Heat speaker. The LM3875 can drive this thing loud…very very loud ”

Here is a link for the Eagle files George zipped together: gcollier-thor-project.zip. “The layout I sent you is a tad different than the one I am using. The differences are very small, only some slight changes to the ground plane and also I put the diodes for the bridge rectifier on board rather than having to use a separate rectifier. I included pads to power it by a battery or a wall wart (in case you want to use it in a pedal enclosure), if you do this there is no need for the regulator and all the associated parts. Definitely DO NOT plug in a battery if you are using the on board supply. You could actually use the battery connection as a take off to power a pedal if you wanted. I’m sure this layout could be made even smaller (rotating all the tone control components 90 degrees would likely do it).”

For reference, here is an Eagle3D rendering of the layout George sent:

“Thanks for providing such a great layout to modify…so many sites just provide PDF files, the Eagle files are very useful!”

Wiring up the off-board components, particularly a 3PDT switch, can be confusing. There are many good explanations of how to do it (see for example geofex.com, tonepad.com, and generalguitargadgets.com) and this one adds to the pile by breaking down the logic of one of the more elegant layouts with a series of detailed figures. I walk through the case where the audio jacks are not insulated from a metal enclosure, there is an LED to show when the circuit is on, and when the circuit is off there is simple by-passing with the circuit input grounded.

It seems simplest to start with the wiring for so-called true by-pass, a straight connection from the input jack to the output jack. The input jack is on the left and the output jack is on the right. They will be reversed to the usual placement when the stompbox is closed up and turned over.

The input jack pictured here is a stereo Switchcraft jack called the 12B. The output jack is a mono Switchcraft called the 11. You can read a post about these jacks in 1/4″ Phone Jacks and Plugs. The switch is a 3PDT Taiwan Blue. The picture shows

1. a white wire from the tip lug of the stereo jack (on the right, for input) to the switch;
2. in one switch position, this will connect to the white wire that goes across the bottom of the face of the switch;
3. which will then connect to the white wire that runs from the switch to the tip lug of the mono jack (on the left, for output).

So we have a simple connection from one tip lug to the other: true by-pass.

In the other switch position, we want to connect the input lug to the input of the circuit and the output lug to the output of the circuit. These are added in the following image:

The blue wire should be connected to the input pad of the circuit board. The yellow wire should be connected to the output pad of the circuit board, or to the middle lug of a level pot if one completes the circuit. I am leaving the board out of these pictures for simplicity. Any unconnected wires in this tutorial are supposed to connect somewhere on a circuit board.

As it stands, we do not need the 3PDT switch because we are only using 2 poles, one for input switching and one for output switching. The third (middle) pole can do the switching for an LED that lights up when the circuit is engaged (or not by-passed). For that we will also need a power supply, which we will get from a DC voltage supply.

This image shows the LED wiring from another vantage point, with the wires for the guitar signal removed for clarity. The LED switching opens and closes the ground connection for the LED circuit. The ground for the circuit is the sleeve lug of the output jack.

• The DC jack has a direct wire to that lug: the green wire that runs all the way across the middle of the picture.
• The LED also connects to that grounded lug through a resistor (2.2K for limiting current) and two green wires, one that goes from the LED to the switch and another that goes from the switch to the lug. Note that these two wires are connected when the switch is in the “not by-passed” position.

Also note that in this particular setup, the sleeve lugs of both jacks are connected through the aluminum enclosure that holds them. The entire stompbox is grounded through the output cable. So the input sleeve lug is grounded by its connection to the output sleeve lug through the enclosure.

In setups with insulated jacks, one must make these connections with wiring. You should still ground the enclosure in those cases because this improves the ability of the enclosure to shield the circuit from outside radio frequency (RF) signals.

Here is a close-up view of the DC jack connections:

The top lug is the positive power supply connection and the angled lower lug is the ground connection. We will use the third middle lug later when we hook up a 9V battery as an alternative power supply.

The red wire is the positive power supply. This colour is consistent with the leads found on most 9V battery snaps: red is positive and black is negative (or ground). In these pictures, I am using green for ground because it shows up better.

I prefer to use the DC jacks that are fastened with a nut on the outside of the enclosure and that is what is pictured in these figures. DC jacks also come configured with the nut on the inside of the enclosure. I find this inconvenient because it requires me to install the jack in the enclosure before I solder the wires to it. As a result, if I want to remove the circuit from the enclosure then I must unsolder these wires. The input and output jacks, the 3PDT switch, and any pots all have their nuts on the outside. If the DC jack does also, then one can remove the nuts and the whole circuit lifts out of the enclosure completely connected.

Here is a close-up view of the output sleeve lug for ground connections:

At this point, two wires are supposed to soldered to this lug. One wire is coming from the DC jack (not shown) above. The other wire is “flying in” from the switch.

Here is an image of the switch wiring with all of the wires in place: input, output, and ground connections:

Note that there is an additional green wire. This is the short wire that connects the first (input) pole of the switch to the middle (ground) pole of the switch.

• When the switch is in the by-pass position, this short green wire connects the input of the PCB to ground.
• When the switch is in the engaged position, this short green wire does not connect to anything.

This additional wire feeds the stompbox circuit a quiet input signal when the circuit is by-passed. That is the trickiest part of the switch wiring, making a nice use of that otherwise unused lug on the switch.

Now we are ready for the circuit board. Besides the input and output connections, the board needs the positive and ground connections which come from the same places as for the LED circuit: the positive lug of the DC jack and the sleeve lug of the mono output jack.

Wires for those connections appear in the figure above. Generally, it is good to run your positive supply lines next to ground lines. This is true of PCB traces as well. So I am showing the positive board supply wire running next to the ground wire for the DC jack.

I am not quite finished. I still need to add the wiring for the battery. It will take a while to make a figure for that, but in the mean time it is easy to describe. The red battery snap wire connnects to the remaining free lug on the DC jack. The black battery snap wire connects to the ring lug of the (stereo) input jack. That’s the obvious one facing up to the right of the tip connector. This battery snap hookup accomplishes two things:

1. The battery negative terminal will be connected to ground only when there is a mono plug inserted into the input jack. In that event, the ring connector is in contact with the sleeve of the mono plug and a ground connection is made through the ground lug of the input jack.
2. The battery positive terminal will be disconnected to the LED and the board when there is DC plug inserted into the DC jack.

Because of these properties, the battery will supply power when there is no alternative DC power supply and there is an input for the stompbox. Otherwise, the battery is preserved.

If you want to etch a PCB with a layout in Eagle then you will need to create an image like this one to transfer your design. This brief tutorial explains how to set things up so that you can use the Eagle export command.

Let’s say you are starting with this layout. This is Joe Davisson’s Antiquity Fuzz from his Analog Alchemy site.

First, change the background to white by entering the command “set palette white;” and then the command “window;” (or press function key F2 to refresh to the screen and see the change. I get this:

Next, display only the traces and pads by entering the command “display none bottom pad via;” to get something like this:

If you have any ground pour, remember to run the “ratsnest;” command. For this layout, I ran the GND polygon all the way around the board so that I get

Finally, enter “export image pcb.png monochrome 600″ and you will create a .png format graphics file at 600DPI that looks like this

The file will have the name pcb.png and it will appear in the same subdirectory as your board file. You can print this file with MS Paint or insert it into MS Word and it will print to scale. This is true no matter what resolution you choose for your file. For example, 300DPI works well for PnP Blue transfers to copper clad boards.

[[Show as slideshow]] ]]> /museum/gaussmarkov.net/parts/connectors/slide-switch-tutorial-2/feed/ 2 /museum/gaussmarkov.net/circuits/noomerang/ /museum/gaussmarkov.net/circuits/noomerang/#comments Tue, 26 Feb 2008 06:01:58 +0000 stobiepole /museum/gaussmarkov.net/circuits/noomerang/

The Noomerang is a wah pedal by B Tremblay of runoffgroove.com fame. It’s a variant of the Maestro Boomerang wah, which itself is a nice alternative to the usual Cry Baby clones, with some added goodies. Unfortunately, the schematic seems to have slipped by without receiving much attention (having only been mentioned once on diystompboxes.com – here’s the link). It’s not terribly different to the standard Boomerang circuit, the most important differences being the addition of a Q trimpot and a 33k resistor added to the board so that a standard 100k wah pot can be used instead of the 25k pot found on the original Boomerang. But both additions are clearly improvements on the original.

The layout has been designed to fit a standard wah shell of the kind sold by Smallbear. I’m very happy with the sound of the Noomerang – a bit smoother and richer than a standard wah. Initially I used 1uF film caps for C2 and C5, but I got DC leakage that resulted in a crackling noise, like a bad pot, at the treble end of the wah’s range. It seems that the polar nature of electrolytic caps is an advantage here (perhaps tantalum caps would work even better, but I haven’t tried them).

Yo. Here’s a layout I did for the Hornby Skewes Zonk Machine. I used the schematic from the Fuzz central website. I put an extra pad for the .47 cap since I couldn’t find a package big enough for the Xicon greenie .47. I also added some GND pads. I usually just connect my footswitch ground to the input jack ground lug but some people might need those extra pads.

I built one up using this layout the other day and I love it. Finding transistors that bias up in it is a total pain though … Be sure to check out R. G. Keen’s good info on biasing the Zonk Machine.