Practical Electronics/Plugins

Plug-in modules, or plugins are small electronic modules that fulfill a (usually simple) function and are capable of being plugged directly into a breadboard. Their purpose is to allow common parts of a circuit to be "plugged in" to reduce time spend breadboarding common parts. Common plugins are astables, switch debouncers, etc. They can be highly customised, and can be as simple or as advanced as you like.

Construction
They are often made from stripboard and use 0.1" headers to make the connection to the breadboard. These headers are usually parallel to the stripboard, so the plugin stands vertically.

They are usually made as small and narrow as possible to avoid making unnecessary clutter on the breadboard. This means that resistors are often mounted "vertically" to save space, at the expense of ruggedness. Beware of this when inserting and removing plugins, as these components can easily be damaged or damage the track they are soldered to.

Modifying the headers
The least expensive headers available are the straight variety. They cost a few pence each for headers with only a few pins, to up to about 50 pence each for up to 15 pins.

To make the plugins, these need a 90° bend in them. This is best done by using a pair of long-nosed pliers to bend the shorter end (the end normally put through the board) over towards the front of the header (the side without the backing plate). The length the pins come at is ideal for this application, so they do not need pushing of pulling through the plastic body yet.

When the required pins are bent over (you may not need all of the pins on a given header), then you can push them through the body so that only half the previous length remains above the plastic. Then, place the bent ends through the holes (they should project about 1 mm past the copper strips), and solder in place. Use the pliers to pull off the plastic body, and discard.

Power Supplies

 * 5V 1A Regulated Power Supply

Signals and Amplification

 * 555 Astable. Includes optional mark-space variance.


 * 1Hz Crystal Oscillator. Uses a 32.768KHz crystal to provide a precise 1Hz output to drive timers, etc.


 * Audio Amplifier. Good for listening to signals.

Input

 * De-bounced tact switch

Decoding, DACs, ADCs

 * R2R DAC. 8-Bit, but can be easily expanded.