Roland Trigger out for the MB-808

As an add-on to my MB-808 I have built this small circuit to trigger the internal sequencer of a SH-101 as well as the the arpeggiator of a Juno-60. The original trigger signal of the Roland TR-808/606 and some other Roland instruments has a square waveform with a duration of 1ms, and a minimum of +2,5V, while the trigger signal from the MB-808 circuit is way shorter; With the friendly help of some people at the german synthesizerform I built this small circuit, grabbed the two trigger signals from the shift registers of the Midibox Sequencer, activated these two external triggers in the Midibox firmware and led the two trigger signals to external jacks on the back. Quite easy, and a lot of fun!


2 x 2N3904
R1 = 47k
R2 = 10k
R3 = 47k
R4 = 4k7
R5 = 10k