Professor Ng said that it is often useful to use a pre-trained neural network and just train the final layer when we do not have much data available. However, I don’t know how and where to download these neural networks. Is there a repository or something on the web?
Here is a tutorial for transfer learning which downloads a pre-trained NN. Here is a list of other models you can download by the same way as done in the tutorial. Here is a hub of pre-trained models but you will need to look into how to use them. Lastly, if you have the name of a model you want to try out, you might google it and see if a pre-trained version is available.