Summary of Contents for Zeppelin Design Labs cortado mkII
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Page 1: Assembly Instructions
CORTADO MKII Assembly Instructions BALANCED PIEZO CONTACT MIC ZEPPELINDESIGNLABS.COM • 2950 N. WESTERN, CHICAGO, IL 60618... - Page 2 Balanced Piezo Contact Microphone © 2016 ZEPPELIN DESIGN LABS. NO PART OF THIS DOCUMENT MAY BE REPRODUCED WITHOUT WRITTEN PERMISSION FROM THE AUTHOR. ZEPPELIN DESIGN LABS TAKES NO RESPONSIBILITY FOR ANY DAMAGE OR HARM THAT MAY COME TO ANYONE OR ANYTHING THROUGH THEIR PRODUCTS. THE CORTADO IS UNDER THE CREATIVE COMMONS SHARE-ALIKE LICENSE, WHICH MEANS YOU ARE FREE TO ADD OR BUILD UPON THIS CIRCUIT IDEA IN ANY WAY YOUR CREATIVITY ALLOWS, BUT ANY DERIVATIVES MUST BE SHARED USING THE SAME LICENSE.
- Page 3 So with the intention of getting the most out of a piezo sensor, we here at Zeppelin Design Labs have developed The Cortado -- a balanced piezo contact microphone. This mic contains a phantom powered circuit that properly matches the piezo sensor input impedance and drives the signal via a balanced output, which allows for wide bandwidth (~20Hz-20kHz), low signal losses, and high signal to noise ratio.
- Page 4 WHAT YOU WILL NEED Here’s everything you will need to build The Cortado DIY kit as shown (Figure 2 on page 4). TOOLS 1. Digital Multimeter, able to measure Resistance 2. #2 Phillips Screw Driver 3. Small flathead screwdriver 4. Ruler 5.
- Page 5 Zip Tie ST-10-23 Nylon Hex Standoff M3x12 FA-60-37 Phillips Machine Screw – Pan head M3x6 EN-30-01 Tin Box PL-10-42 Cortado MKII Label Sticker PL10-90 Serial Number Sticker HD-20-02 Rubber Grommet PC-41-01 Printed Circuit Board Potentiometer Trimmer 5K R3, R6, R7, R8...
- Page 6 HD-40-30 TD-10-22 CB-20-18 CB-01-30 CB-01-69 TP-30-11 TP-20-14 HD-08-01 ST-10-23 FA-60-37 EN-30-01 PL-10-42 PL-10-90 HD-20-02 PC-41-01 R3, R4, R5, R8 R1, R2, R6, R7 C1, C2 Q1, Q2...
- Page 7 THE PRINTED CIRCUIT BOARD Whatever configuration you are building, all Cortados start with a circuit board. Your work space should be well-lit, well-ventilated, and disposable; that is, don’t work on the nice dining room table! Work on a utility surface that you can burn, drill and scratch. A piece of ¼” tempered masonite, or a chunk of MDF, makes an excellent cover if you don’t have a utility work bench.
- Page 8 The printed circuit board (PCB) holds the components in this circuit. All of the components will be installed on the “component side” of the board, which is the side that has the part numbers on it. The other side of the board is called the “solder side”, which, as the name implies, is the side on which the legs of the components are soldered to the board.
- Page 9 a. Start with the 3.3M resistors (R1, R2, R4, R5), labeled ORANGE, ORANGE, BLACK YELLOW, BROWN. Compare to its picture in the BOM. Find their locations on the circuit board; install and bend the leads as described above (3). Don’t solder any of them until all 8 resistors are installed;...
- Page 10 d. Now clip each lead with your flush cutters at the solder joint (7). e. Before installing any more components on the circuit board, double check the resistance values of each of the installed resistors. Set your digital multimeter to the “ohms” or “resistance”...
- Page 11 3. Trimmer Potentiometer: Place VR1 in it’s location with the adjustment screw located toward the PZ holes. Solder and clip the leads (13). 4. Transistors: This circuit contains three field effect transistors (FETs). FETs are quite sensitive to static electricity and could easily be damaged if they are exposed to moderately high voltages. The voltage rating of these FETs is only 35V, meaning that if over 35 volts is applied across two leads on one of these components it will most likely be damaged to the point of not being usable.
- Page 12 Two of the three FETs have silver paint on their face. We painted them to indicate that these two FETs have been “matched” to each other. This means that the gate-source turn-off voltage of these transistors were measured to be within about 100th of a volt of each other. This allows both sides of the circuit to be balanced very closely, achieving very high common mode rejection, which results in a very quiet microphone.
- Page 13 5. Grounding wire (Part # : Strip about ” off of both ends of the black grounding wire CB-01-30) (20). Place one of the ends of the wire in one of the holes in the corner of the board (note the picture) (21,22).
- Page 14 XLR JACK All Cortado configurations use the same XLR cable. Prep the Mic Cable, part CB-20-30: Cut the mic cable into two pieces, about 18” (45cm) and 12” (30cm) long, or to suit your application (26). Note that if you are going to install the entire Cortado inside a shielding container, like a Tin Can Mic, you will only need one piece of mic cable.
- Page 15 e. Strip off about ” (3 mm) from the white and red wires (30). Tin the twisted copper shield wire, the red wire, and the white wire (31). g. Repeat Step 1a - 1f for the other three cable ends. 2.
- Page 16 b. Solder the white wire to Pin 2 (36). c. Solder the red wire to Pin 3 (36). d. Solder the ground wire to Pin 1 (37). 4. Reassemble the Jack: a. Slide the strain relief up to the pin insert. Make sure the key on the insert is aligned with the key on the strain relief.
- Page 17 PIEZO DISC From this point onward, sections of the manual are specific to your application. The piezo disc and its connection to the circuit must be carefully shielded. The procedure is the same for the Standard Contact Mic and the Instrument Pickup: you attach the piezo to the remaining piece of mic cable, then wrap the piezo in electrical tape, and then copper tape.
- Page 18 b. Solder the red wire to the brass part of the disc (41,42). 2. Now you need to electrically insulate the piezo disc. When we make Cortados in the lab, we use Plasti-Dip tool handle coating, but you can use electrical tape. a.
- Page 19 Use your scissors to trim off the excess tape to within about a millimeter around the edge of the disc (46,47). 3. Shield with copper tape: a. Cut two pieces of copper tape about 2- ” long. Use one piece of copper tape to wrap the disc in a similar way as with the electrical tape (48,49).
- Page 20 c. With as little heat as possible, solder the two pieces of copper tape together on the top of the disc (51). Also solder the shield of the microphone cable to the copper tape. Make sure the back of the disc remains flat so it can be mounted on a flat surface (52,53). That’s it! Move on to the FINAL ASSEMBLY chapter, and find the section specific to your project..
- Page 21 2. Solder the wires to the piezo disc (56). The ceramic part of the disc is very sensitive to heat and can be tricky to solder to. For your convenience, we have tinned the disc to make soldering easier. The best way to successfully solder wires to the disc is to lay the tinned wire on top of the tinned part of the...
- Page 22 FINAL ASSEMBLY Jump to the section appropriate to your project. STANDARD CONTACT MIC 1. Prep the container: a. Drill a ” (10mm) hole on both ends of the metal tin, ” (7mm) up from the bottom. (62,63) This is more likely to be successful if you start with a smaller bit and re-drill a few times with progressively larger bits.
- Page 23 2. Attach the grounding wire: a. Use a bit of sandpaper or your flat head screwdriver to scratch up a tiny patch in the corner of the can. With your soldering iron, tin this area (67). b. Solder the ground wire to the tinned area (68,69). 3.
- Page 24 b. Solder the XLR cable to the PCB (71,72,76). The red goes to the hole labeled XLR3 and the white wire goes to the hole labeled XLR2 The copper shield wire goes in the round hole labeled XLR1. c. Slide the piezo disc cable through the other grommet (73). Solder the red wire to the hole labeled PZ1.
- Page 25 5. Install the PCB into the metal can: a. Screw the PCB stand-off to the metal can via the hole in the bottom of the can (77). b. Fasten the zip ties around each of the cables on the inside of the tin (78). This acts as a strain relief and protects the solder connections.
- Page 26 c. Place the Cortado Label sticker on the top of the box (82,83). Your Cortado Standard Contact Mic is done! TIN CAN MIC, OR OTHER SHIELDING CONTAINER If you are making the ZDL Tin Can Mic, you should be reading our Instructable from this point on. When the entire Cortado is installed inside a grounded shielding container, like a tin can or garbage pail or steel sculpture, it does not require additional shielding.
- Page 27 It’s time to set the bias, so please turn to “SETTING THE BIAS” on page 30. Once the bias is set, your Cortado is complete, and ready to install inside your shielding container. This can be made of anything that conducts electricity. You must connect the grounding wire to the container itself; the PCB must NOT touch the container.
- Page 28 4. Wrap the entire PCB and exposed cable wires in electrical tape (89,90,91). 5. Very carefully remove the backing from the remaining piece of copper tape. Very carefully wrap the copper tape around the circuit board. The goal is to encase as much of the circuit board as possible.
- Page 29 6. If you cut the copper tape into two pieces, put a solder joint spanning the edge of the two pieces so they will be electrically connected (94). 7. Solder the ground wire anywhere on the copper tape (95). When soldering the copper tape make sure you don’t use too much heat which could melt the electrical tape under the copper.
- Page 30 SETTING THE BIAS In setting the bias of your Cortado MKII, you are simply adjusting the amount of nominal current that is passing through the FETs, Q1 and Q2. The more current that passes through the FETs, the more gain the circuitry will have on the signal from the piezo disc.
- Page 31 3. Turn the trim pot (VR1) until the voltage on TP is .075V (101). This will set the bias current to .25mA per FET. In the lab, we always start out setting the bias to this current, because that seems to give a good balance of output volume and common mode rejection.
- Page 32 USING YOUR CONTACT MICROPHONE There are about as many applications for the Cortado as there are sound sources in the world. Please read this section carefully to learn how to get the most from your contact mic and how to use it properly. With some basic supplies and a little creativity your Cortado contact mic should give you years of great service.
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Page 33: Phantom Power
If the device you are plugging the microphone into doesn’t provide phantom power then you need to use an external phantom power supply (available at most pro-audio stores). Zeppelin Design Labs is currently developing an external phantom supply DIY kit which should be available soon.