Fun with Crackleboxes - The KrackleCat


The Peasant has been experimenting with the legendary Kraakdoos, or "cracklebox", as seen here.

It was decided to see how small this device could be made without losing functionality or sound quality. The biggest limiting factors were the battery and the speaker, as the actual electronics and touch pads could be made very small quite easily. A small speaker and a plastic pill bottle with the same outside diameter were chosen for the project. The pill bottle was then cut down to the smallest size that would still allow the speaker magnet and basket to fit inside. The resulting pill bottle bottom could then provide a baffle for the speaker as well as an enclosure to mount the circuitry.

A circle of metal speaker grille material was cut out of an old portable stereo to protect the speaker. A plastic 9 volt battery holder was also obtained. Below is a picture of the larger parts used in the project:

The battery holder was bolted to the pill bottle bottom, and the electronics and speaker were installed as shown below. The circuit for this project is quite basic with only a few parts, so all the parts were wired together point-to-point and epoxied in place without using any circuit boards. A touch pad pcb was etched and epoxied to the top of the battery holder.

The project functioned well immediately after assembly was complete, emitting a wide range of fun and interesting sounds. The battery holder and speaker baffle design made the device somewhat resemble a four-legged animal in looks, so the name "KrackleCat" was coined!

Here are two completed KrackleCats:

The second unit was built a bit differently from the first one, with the circuitry and touch pads mounted on some perf board on the top of the battery holder. Metal test point pins were used for touch pads instead of the flat pcb pads. Functionally, the two KrackleCats are identical, but the more traditional flat pcb touchpads are a bit easier to use than the metal pins.

Here is a KrackleCat in operation:

The Peasant also experimented with adding a microphone input to the KrackleCats. If you would like to try this, you can use the simple microphone preamp circuit below.