Yiddish diminutives, a very short question

I'm looking for Yiddish diminutives of "Yitzhak" and "Elisheba". I've tried:

- googling
- baby name site (utterly useless)
- looking up this presentation, which, while very useful, did not contain diminutives for either name I need

I found the diminutive "Sekel" for Yitzhak, but googling it brought up only surnames, so I'm unsure how accurate that is.

Thank you in advance!