Here is the bad news. If your contribution is the idea alone, you are unlikely to find a developer to do it for equity alone. If you have some kind of unfair advantage, it would be different. If you are going to do non tech roles like sales, fund raising etc.. It would be different. Also if you need them just to create the initial product or be a tech founder, it would be different.

If you pay a minimal amount for the development, the amount of equity needed would be reduced.