Saturday, December 26, 2009

Guitar Amplifier

Well, I committed to build a guitar amplifier for my nephew and figured I might as well build two. One for my son Evan and the other for Kyle. This is another of those projects that have been mulling around in my brain for a long time. Here are the specs I wanted and what it should do:

  • Multiple inputs for a couple different things:
  • A very clean high impedance input for acoustic guitar pickups and for electric guitars for really clean sound
  • One input specifically designed to be over driven and give the "not clean" fuzz sound
  • Line level inputs for playing along with an iPod or similar 
  • Headphone amp for when it has to be quiet!
Having built a stereo amp recently using two "Gain Clone" boards from
I figured I would use these and have a 68Watt little screamer. Here is the driver I am going to use from Parts Express The 8" Driver

Having learned a little more about Eagle I drew up my Schematic Diagram and started assembling the parts. More to follow!

Update: Design phase is complete and I started breadboarding up the design. Here is initial scematic. Not sure how this will look... The clean channel uses a non inverting opamp with a one megohm input impedance. The other channel uses a CMOS inverter chip as an analog amp. Design courtesy of Craig Anderton from Electronic Projects for Musicians, Guitar Player Books 1980

Sunday, September 27, 2009

Eagle Update

Well, thanks to some tutorials and discussion with my buddies, (who actually layout circuit boards) I think I am ready to send this thing off to have my digital files turned into an actual printed circuit board... Highlights of lessons learned so far:

  • Even though you send the power supply signals to all the IC chips, you need to send them to a pad that you can use to connect the incoming power.
  • You have to draw a polygon, not a rectangle to fill in for a ground plane. Then to connect, assign the signal name that you have assigned to Ground to the polygon. 
  • Make sure you are on the right layer when doing things.
  • "Save the project as" using sequential file numbers so you can come back to versions and experiment more.
All in all, I am learning something new! And, that is what life is all about...


Monday, September 21, 2009

Eagle Update

Well, I am still learning. I am laying out my first Mic Preamp based on the Bur Brown INA103. It can run on 24 volt rails so I am going to do that. It should be a simple project to layout too... You may have noticed that TI bought Burr Brown several years back. They still make the chip and digikey carries it. If you want to learn Eagle there are some great tutorials on Sparkfun's site here. The nice thing is the circuit is simple enough I should be able to see if I have any gross errors before I get a board made. I spent most of tonight figuring out exactly what a  Capacitor is in Eagle. As in: What size do you want the holes in the PC board to be? And, how far apart should they be from eachother? Coolness! A day learning something however small is a good one!


Sunday, September 20, 2009

Learning Eagle

Well, I have done many projects in the past. You may remember me for a series of DIY articles in Recording, EQ, Electronic Musician and others. I am coming into the 21st century and finally learning to layout boards using Eagle Schematic Capture and Board Layout. You can get a copy from here Eagle So far I have gone through a morning's worth of tutorials and I think I am starting to get it. Back in the Old Days I would use a Radio Shack Perf Board, part number: 276-168, which is still made. But, once I have it layed out in Eagle, it is easy to get multiple boards made and share the design. So, time to get hot for me! Here is a list of things I am working on:

  • LED Light Ring for Macro shots on a camera. It will use about 12-20 white LED's and have a switching power supply so it can run on a couple AA's
  • Mic Preamps... Couple of them. Time to finish several designs that I started a while back. 
  • Mic Preamp specifically for use with a Video Camera. So you can plug two XLR connectors into it and then plug it into the camcorder by a stereo 1/8" jack. They make these but they cost way to much for what you get.
  • 900 Lumen Single LED Bike Light. Got the LED already. I have a P-7 and a CREE one too. The P7 has four dies in parallel on the module and runs at 2.8 amps at about 3.7VDC. The CREE try's it the other way, four in series so you get  700ma of current but you got to drive it around 14-15 VDC. I think I know which one makes  more sense.
  • Oh yea, multiple RGB LED projects including a 8X8X8 cube. Like this one:

    So, this is my blog and I'm getting started! Woo Hoo!