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Datasheets : Other PCB Design Software
If you do not have access to Livewire, Circuit Wizard, PCB Wizard or Crocodile Technology, but do have alternative PCB design software, it is still possible to use the data sheets to produce PCBs. We do not recommend this approach because it is much easier to make mistakes. However, these notes are included to show what would need to be done and the associated problems. Suppose, for example, that the system planned is a night light – a lamp should light when it is dark. A suitable block diagram might be:
The signal from the Light sensor will go low when it is dark, so the signal from the Inverter will go high, which will switch on the Darlington driver and the Bulb will light. Read the data sheets for the planned subsystems and make sure they will work as planned. In the case of the present system, looking at the data sheet for the Light sensor we find that we can simplify the circuit by using a Dark sensor, and missing out the Inverter:
First use the data sheets to help draw a circuit diagram by combining the units. In the present case it might look like:
It is important to test the circuit before designing the PCB. If you do not have circuit simulation software available, then use a systems kit or prototyping board. Once you are sure that the circuit operates as planned, the PCB can be designed. To do this you will need the dimensions and pin numbers of all the components. Then, using the PCB design software available to you, taking into account the circuit diagram connections and the information on the components, lay out the pads for each component and the connecting tracks for the PCB. Obviously the appearance of the PCB will depend on how it is designed and also on the PCB design software used. As an example of what might be achieved, a piece of free downloadable software called Pad2Pad was used to design a suitable PCB.
As is typical with general purpose software, the only components that it was possible to place were resistors. In the case of all the other components it was necessary to simply place pads at the correct positions. This makes it much more difficult to interpret the PCB and relate it to the circuit diagram. It is prudent to check the PCB against the original circuit design before spending a lot of time making the PCB. Print out the PCB and the circuit diagram. Check that each track on the PCB corresponds to a connection on the circuit diagram (a good way to do this is to mark each track and connection with a highlighter). The connection to the bulb is via a 2-pin terminal block (top right). The software used to produce the files for these notes was Pad2Pad version 1.6.0.
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