This plugin consists of a single 555 Astable. This plugin is very versatile, and can be used for any number of things, but it often is used to give a clock to run a circuit. The plugin below gives a pulse of about 2Hz with a very low mark-space ratio. The circuit diagram is given below.
This circuit obeys the following formulae with regards to its frequency and mark space ratio.
- This is different to the design equation for the standard 555 Astable. (R2 instead of 2R2)
The values below give a frequency of about 2Hz, with a mark-space ratio of about 1:50.
The stripboard layout is as shown below with a component list.
To give this plugin an enable pin, replace the wire link from Pin 4 to +V with a 10K resistor going from Pin 4 to ground (Pin 1). Then add a header pin to Pin 4. A high signal on this pin will cause the astable to function, a low will disable it, locking the output low.