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Giant Little Drummer Boy

I build a giant version of the Delptronics LDB-1 “Little Drummer Boy” analog drum machine kit.
It is pictured below next to the standard kit to show the scale.

Giant LDB-1 Drum Machine

 

The actual assembly was not difficult. Of course, when I assembled the kit, I skipped all of the parts that would eventually be panel mounted. Instead of getting all new panel mount jacks, I could have positioned the PCB at the back edge of the enclosure and drilled holes for the board-mounted jacks to come through. However, lining up the holes is such a hassle that panel mount parts are just easier. Once the parts were soldered on the PCB, I soldered wires for all the jacks, buttons, LEDs, etc to the board, then to the panel mounted parts.

Here is a color-coded diagram of the LDB-1 PCB that will be very helpful if you want to build it with externally mounted parts.  The pads that you need to connect to are green.  Some pads are gray to indicate that there is no panel connection, just for extra clarity.  I colored the ground pads blue so you know you can wire them together on the panel.  Keep in mind that this is a bi-polar circuit, so the negative power connection is V-, not ground.

All told, it was about $100 in extra parts, plus $140 for the kit, plus about eight hours of work. The result is well worth it. I now have the biggest Little Drummer Boy on the planet! Of course, being the inventor of the LDB-1, I had a head start, but I would love to see what other people do with the kit.

These were the extra parts I needed, with links for some of the less generic items:

Read more: Giant Little Drummer Boy

Passive Matrix Mixer

I recently built a 5x5 passive matrix mixer. A passive matrix mixer is one that contains no active components, that is, no amplifiers, buffers, or anything that uses electricity. The signals are mixed through resistors, and are attenuated by potentiometers. I also included switches so that the level can be set with the pot, then turned on and off with the flip of a switch. One thing to keep in mind about a passive mixer is that it works best if the signals are fairly hot. Line level signals will work, but will not give you much headroom in the volume department.

 

This is what the big boy looks like:

 

Passive Matrix Mixer

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Experimental Garage Sale 5

Saturday, June 9, 2012
Noon - 6pm

Experimental Sound Studio
5925 North Ravenswood Ave.
Chicago, IL 60660
[map]

The Fifth Annual Experimental Garage Sale will feature Circuit Bent Instruments, Un-Bent Gear, Parts, Vintage Components, Custom lamps, Kits, Art and a Raffle.

A dozen vendors from around the country will be there - including Mickey Delp / Delptronics!

More info at GetLoFi.com

Austin Maker Faire 2012

Austin Maker Faire

Saturday, May 12, 2012 @ 10am

Pine Street Station
1101 E 5th Street, Austin, TX

Buy Tickets

Electronic Sound Synthesis
All sounds are electronic - after all, the human ear converts sound waves into electrical impulses that get sent to the brain. Mickey Delp will explain how a synthesizer turns electrical impulses into sound waves. He will discuss the basics of electronic sound synthesis which covers electronics, physics, biology, and history. Then, he will dive into the inner workings of a synthesizer, demonstrating and explaining fundamental parts of a modular synth. Mickey will also make lots of weird noises for your enjoyment!


NOTE: It is basically the same talk that I gave at Nerd Nite Austin back in March. Here is the video from that event:


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Bender Sequencer with Monotron and Gakken Synths

The most commonly asked questions about the Bender Sequencer are: “I have/want to get a Bender Sequencer, so how do I hook it up to my ___?” and “What is the easiest device to hook up to the Bender Sequencer?” Well, here are the answers.

In this article, I will show how I use the Bender Sequencer to control the Gakken SX-150 and Korg Monotron mini synthesizers. I chose to discuss both the SX-150 and Monotron in the same article because they are popular, inexpensive, and very similar. As has been oft noted, the SX-150 is packaged with a magazine that includes a photo of Gakken showing the SX-150 to Korg engineers in 2008, two years before the Monotron was released. Coincidence? Not likely, but let's put aside conspiracy theories and get to work.

The main similarity between them is that they both use a ribbon controller to control the pitch. The SX-150 uses a stylus touched to a ribbon and the Monotron uses a pressure sensitive ribbon. Slightly different hardware, but exactly the same concept. In both cases the ribbon is simply a variable resistor. You could disconnect the ribbon and hook up a simple potentiometer (pot), and the synth would work exactly the same. That is a key point. After all, the Bender Sequencer is designed to connect to a device at the pitch resistor (variable or not). So, these two devices are perfect candidates for sequencing.

Read more: Bender Sequencer with Monotron and Gakken Synths

TENMA 72-7935 Multimeter Review

 TENMA 72-7935 Multimeter

The TENMA 72-7935 Pocket Sized Digital Multimeter has a big feature list but a miniscule price.

I have had fun reviewing products as part of electronics supplier Newark's blogger outreach program. When they asked me what I would like to review next, this little puppy came immediately to mind. I had seen it on the Newark web site and I was curious as to how a multimeter with so many features could sell for only $15. Well, I put it through its paces and found out what it can do.

Read more: TENMA 72-7935 Multimeter Review

Nerd Nite Austin #32

I will be presenting a talk on "Electronic Sound Synthesis" at Nerd Nite Austin on March 7th at 7pm.


UPDATE: Here is the video of my talk!


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