Picture of Analog Beat Box
This is an analog circuit that plays a synthesized drum beat. It can be scaled in amount and the quality of the noises.  

Step 1: What You Need

Picture of What You Need
1 power source
3 breadboards
Wires (Yellow, Blue, Red, and Other) if you feel like following conventions
2 Speakers
6 OPA551 Op-Amps
2 TL081 Op-Amps
4 2N3904 NPN Transistors
2 10kOhm potentiometers
2 diodes
2 LEDs (optional)
3 200kOhm
6 1kOhm
2 4.4kOhm
1 3.7kOhm
3 1.7kOhm
2 160kOhm
3 5.8kOhm
4 0.1uF
2 0.047uF

An Oscilloscope for debugging can come in quite useful.
Wire stripper/cutter


i'm really interested in experimenting with this, do you have any suggestions for a replacement for the opa551? thanks!

Since the outputs are buffered by the transistors, you don't need the
opa551. In fact, none of the outstanding features of the opa551 are
important for this (high voltage/"high" current out). A simple and
generic op amp like the lm124 (which has 4 op-amps in it) would probably

good to know, I'll start with whatever opamps i have and see how it goes. thanks!

rlychpmn (author)  choklitlove1 year ago

The opa551 was what we had readily available. I would agree that it was probably over specced for this application. The opa37 is quite a bit cheaper.


There are definitely some places in the circuit where a TL081 would have worked as well.

awesome, thank you very much!