IPad – Circuit Simulator for iPad

An iPad doesn't offer the same capabilities as a Wacom graphics tablet. At best--Eazel excepted--you'll only be able to control the cursor on the mac or pc. There are many of those types of programs for the iPad in iTunes from the free touch mouse (iPhone only) to iTeleport (iPad, US$25).

Graphics tablets aren't that expensive, especially compared to an iPad. The cheapest Wacom tablet in the USA goes for $200 or so. Ask someone you know to give you one for your birthday or appropriate holiday. If you know enough people, you might even be able to find one for free. I gave away my old Wacom Graphire last year when I bought a new Intuos. Ebay shows used Graphires for a variety of prices; make sure used tablets include the pen and mouse.

I also have made video tutorials using a graphics tablet and Photoshop. I have not settled on which video capture software to use. There are too many for me recommend one.

You may want to take a look at Codify. It's meant for creating games, but it should do animations just fine.