How to loan LLC money

[Patricia N.]

I am the sole member of an LLC. I capitalized the LLC with 1K several years ago and only have $400 left in the bank account. I would like to loan the LLC another $600 while I try to get the LLC up and running.

Could I create a promissory note, charging yearly interest, and demand a one time time balloon payment at the end of the loan in say 2031?  I would rather not have to remember to pay installments every year. 

Once I start earning money, I will hire an attorney...right now my company is super tiny.