An astable multivibrator circuit designed in Altium Designer
To design the circuit I used the following online guide for an astable multivibrator circuit
An Astable Multivibrator (Also known as the flip-flop circuit) is a circuit that continuously oscillates between two states. Using transistors, capacitors, and LEDs we can build a circuit to demonstrates its function.
- The transistor needs approximately 0.7V at the base pin to turn on
- Since we are using a 3V supply we will need to use an LED with a low forward voltage (Red & Yellow)
- The arrangmenet of LEDs will be in parallel so that they all have an equal voltage drop
- I will place a resistor in series with the LED to protect the LED from burning out
- Our targe current for each LED will be 10mA (In parallel that is a total of 50mA) so we will need a 24 ohm resistor
- I will be using an NPN transistor for this application
In this circuit the capacitor charge time determines how quickly the LED oscillates. We can adjust how quickly the capacitor charges by adding a resistor in series. The resistor limits the amount of current that enters and leaves the capacitor. The RC time constant describes how quickly a capacitor charges to 63.2% of it's applied DC voltage. The RC time constant is described by the following formula in a simple RC circuit:
- Time constant (Seconds) = Resistance (Ohms) * Capacity (Farads)
Rather than doing math to determine a desired time constant we can fiddle with some values to see the outcomes of the circuits
Using OrCad PSPice to simulate the circuit below we can alter the values of the resistor and capacitor and see how it affects the time constant
View the BOM to see the parts used for this project
The routes for this project were generated using the autoroute feature. This is not ideal as it can result in a variety of design rule errors. It also does not give you the chance to layout the routes yourself
The following output files were included
- Bill of Materials
- Gerber
- NC Drill
- Pick-and-place
- Board Stackup
- Drill Drawing/Guides
- Schematic Prints
- PCB prints
