Monday, 15 April 2013

Steampunk Electronics–Buzzer

Another part of the internal electronics that I want to incorporate into the Steampunk gun, is a buzzer that sounds when the trigger us pulled.

I found a simple schematic using a 555 IC that flashes an LED and makes a kind of buzzing sound through an 8 ohm speaker.

This schematic seems to be pretty widely available on the Internet, so I thought that I’d give it a go.

The circuit uses a small number of parts and, all together, it cost me about $1.25 using components sourced from eBay.

  • J1 – 2 pin (2.54mm pitch) right angle pin header
  • VCC1– 2 pin (2.54mm pitch) right angle pin header
  • C1 – 1μF non-polarised capacitor
  • C2 – 10μF electrolytic polarised capacitor
  • R1 – 220kΩ resistor
  • R2 – 470kΩ resistor
  • U1 – 8pin DIL socket and NE555 IC
  • LED1 – generic blue LED

J1 connects to the 8Ω speaker and VCC1 connects to the 9V battery.

I have added DuPont female connectors and housing to the wires soldered on to the speaker and 9V snap to make it easier to connect and disconnect them.


I’ve used Fritzing to do the layout of the board (as shown above). This board is approximately 4cm x 3cm, so it would fit nicely inside the prop.

First, I laid the components out on a prototype board and set up the jumper wires to test the arrangement. Once I was happy with the circuit, I used Fritzing to lay out the design (and make the schematic). Then I printed the circuit out onto some photographic paper and cut it to size.

My first attempt to print was pretty poor … I heated the PCB too much and the copper blistered away from the board. This may have happened because the board was a bit scratched from a crappy cut that I made previously.

When I had successfully transferred the design to the board, I then went over the transfer and fixed any breaks with some enamel paint and a fine paintbrush, then … into the acid bath.

I cleaned the board using acetone to remove the resist and drilled the holes with a pin vice.

I then went over the board on the silk side and marked what each of the components and their orientation should be and then populated the board with the components and soldered them up.

I put DuPont connectors onto the speaker wire and the 9V snap so that I could more easily attach/detach them (an so use them on other projects later).

The circuit is described, on the Internet, as a “Laser” sound … frankly, you would need a pretty good imagination to believe that. It’s more of a Geiger Counter sound … but that may be the way that I constructed the circuit. It probably needs a higher hertz to fix that.

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