A different way that might make more money (and sense.)
Put up a poster advertising that your show will start in X minutes – if enough money was deposited into a special box. The box shows how much money has been given, and when it’s close to the minimum target, it shows how much is still needed for the show to start. The poster should also advertise and “sell” the performance since that is the only base for payment the viewers have. A small screen with video highlights can also be used. The box should also stay open to donations during the show.
You would like to know where and when some type of performance or even a specific performer is going to be. It’s also good for the performers to have a bit more publicity.
A website and app that allows you to see what street performances are going to happen around you soon, and even search by category or performer.
Help people give you more money for your performance.
Instead of using a hat or a box, use a device that shows how much money was already deposited.