You cannot choose a partner to develop your product without explaining every detail about it. There exist legal mechanisms to protect your inventions and selective disclosure. Also, be aware that what you think could be a novel idea that no one ever considered, it is more likely that you will have to navigate a large sea of existing products or ideas that share some similarity as part of the patent landscape.
You are under no obligation to tell everything to possible partners at the first email or phone call, but you should be able to explain your project in high level terms without compromising its integrity. The next step would be to establish a confidentiality agreement in writing, and have it executed before you pursue the detailed discussions.
If you find yourself incapable of very precisely describing what your product will be, ask yourself some questions before continuing the process. Work on defining it in the best terms possible with your understanding of the technology.
After all, if your partner is not able to have a clear idea of the product and its features, how can he help you develop a really good product?
What can be done:
At first, check that the inventions are legally protectable? Since no one can work in total isolation and you will need to establish trust with many partners (development, financing, distribution, etc.), working with help from a legal advisor to protect your inventions is a good step in establishing a solid base.
At Motsai, it is part of our process to assist you if you wish to work with patent firms to create intellectual property protection. Even if you are missing an NDA, we will provide you with a straightforward template that you can use to get started in confidence.