Entertainment Circuits: Electronic Cat Noises
This project involves the use of many components not introduced in the previous projects.
These consist of a speaker, a transformer, transitors, a control, and capacitors.
Below I’ve provided the role of each component, and how they function.
Components
Control- A variable resistor which can change how much electricity flow is restricted by by adjusting the knob.
Capacitor- Stores electrical energy, blocks direct current, and permits the flows of alternating current.
- Direct current- A current which flows only in one direction
- Alternating current-A current which flows in one direction till reaching its maximum where it decreases to zero, switches the direction of flow and increases till its maximum and then decreases back to zero. The current alternates between directions continuously.
Transistor- A tiny chip with three connection points B which is the base, C which is the collector, and E which is the emitter. Transistors amplify weak electrical signals, are used as switches to connect or disconnect other components, and can oscillate to allow electrical signals to flow in pulses.
Speaker- Converts electrical energy to sound.
Transformer- Helps match circuits so they function efficiently by transferring electrical energy which is flowing in one part of a circuit to another part.
Project 18: Electronic Cat
Now that I have information on the other components used in this project, I can move on to connecting the circuit.
15-48, 16-49, 17-59-91, 18-63-52, 19-71-75, 40-109, 45-106-72-51, 50-64-60, 76-108, 92-107, 42-43
The connection between 15 and 48 connects the top terminal of the speaker, to the top left side of the transformer with a medium sized red wire.
The connection between 16 and 49 connects the bottom terminal of the speaker, to the top right side of transformer with a short white wire.
The connection from 17 to 59 to 91 connects the base section of the Q1 PNP transistor, to a 0.01 micro farad capacitor, to a 22k resistor with a medium sized red wire, and a medium sized blue wire.
The connection from 18 to 63 to 52 connects the collector section of the Q1 PNP transistor, to a 0.1 micro farad capacitor, to the bottom right terminal of the transformer with a medium sized red wire, and a small white wire.
The connection from 19 to 71 to 75 connects the emitter section of the Q1 PNP transistor, to the 100 micro farad positive terminal of a capacitor, to the 100 ohm resistor with a medium sized red wire, and a small white wire.
The connection between 40 and 109 connects the positive terminal of a battery, to the right side of the key with a medium sized red wire.
The connection from 45 to 106 to 72 to 51 connects the negative terminal of a battery, to the middle terminal of the control, to the right terminal of a 100 micro farad capacitor, to the bottom middle terminal of the transformer with a small white wire, medium sized blue wire, and a medium sized red wire.
The connection from 50 to 64 to 60 connects the bottom left terminal of the transformer, to the right terminal of the 0.1 micro farad capacitor, to the right terminal of the 0.01 micro farad capacitor with two small white wires.
The connection between 76 and 108 connects the right terminal of the 100 ohm resistor, to left terminal of the key with a medium sized red wire.
The connection between 92 and 107 connects the right terminal of the 22k resistor, to right terminal of the control with a medium sized red wire.
And finally the connection between 42 and 43 connects the negative terminal of a battery, to a positive terminal of a battery with a small white wire.
Once all the connections have been made upon pressing the key, the speaker creates an electronic sounding cat noise. By turning the control clockwise the pitch of the cat noise becomes gradually higher. When holding the key down, the length of the cat noise extends.
To hear the electronic cat noises please click here
The electronic cat uses a low frequency oscillator which is composed of the Q1 transistor, and the transformer. The cat noise itself is generated by the 0.01 micro farad capacitor, the 22k ohm resistor, and the control.
Final Thoughts
This Project was definitely harder to understand than the previous ones, but I wanted to challenge myself with a project with and interesting result. I was surprised to hear the cat noise that came from the speaker, and thought it was interesting that the pitch changed when turning the knob. Next project I hope to do something involving the LED lights in the kit.
Sources: Maxitronix Electronic Lab Owners Manual
The Analog Project 