Hey thank you Noodle, Peter, Oldgrey.
I tinkered a while with this circuit using the 9V batteries in series and an Arduino to provide a trigger from pin 13 so I can see the LED flash when it triggers. It currently produces a loud “click”. Definitely sounds like the initial fast attack pop at the start of the 808 bass kick. From what I read, using 9V batteries will only produce this kind of click. So I am waiting for the Adafruit power supply although the DC/DC power supply from Murata looks very good.
I noticed the batteries got very hot rather quickly and lost charge fast.
From what Eric Archer mentioned, the Accent needs to be tied to (+), I am sending a short 5V pulse from the Arduino.
Here are some references for what is necessary for this circuit to work:
Electro-music.com forum thread about this circuit
Original Web Site (archive of Ericarcher.net)
Here is what Eric Archer wrote about the device:
Trigger and Accent inputs - Each drum has a TRIGGER and ACCENT input. In the 808, the accent input is a global signal that boosts the level of all drums when requested (TTBOMK). In my clone, I just have a potentiometer set up as a voltage divider to deliver a constant voltage to the ACC input. It is basically a volume control in this arrangement. The trigger inputs are a little more tricky; if you are driving the drums with a logic circuit, you’ll need a little bit of trigger generator glue inbetween. Basically this lets the energy of the positive transition thru to trigger the drums, and shaves off the negative edge. If you omit the trigger generator, the drums sound weird b/c they will also trigger on the negative edge, with a different and weaker tone, reduced decay time weird.
Youll need a split power supply to make these circuits work. You can use +/-12VDC or +/-15VDC. In a pinch you can make a +/-9VDC supply with two 9V batteries and a pair of battery snaps. Or you can adapt an old PC power supply to make a +/-12VDC bench power supply. Look for instructions on how to hack a PC supply on the net.
Or do what I did: I found that the miniature muRata NDTD0515C DC-DC converter works nicely, boosting juice from a cheap wallwart up to nice +/- 15VDC bipolar power.
From a forum entry:
i’ve just finished building this circuit and have some results to share, for what they’re worth.
i’ve run the circuit at 9V, 12V, and 15V and can say that the sine/click balance is directly proportional to the source voltage.
at 9V the sound is exactly like the samples posted above where the click was by far the most predominant element.
at 12V the sound is very, very close to authentic.
at 15V the sound is as close to owning an 808 as i’ll ever get!
I will post results once I have the circuit connected to the 12V+/- power supply and I’ll post the breadboard.