555 Timer, AC to DC Inverter


Joined Dec 20, 2007
Q1 is supposed to be a TIP41 so don't replace it with a TIP42.
Q2 is supposed to be a TIP42.

The TIP31 has a current rating that is half of what is needed.

We analysed the circuit before. Its output is not a sine-wave and its voltage is far too low because the losses in the circuit are very high.
It does not work!

Why not buy parts from a real electronic parts distributor? The TIP42 from RadioShack is actually an MJE34 that is very, very old.


Joined Jan 8, 2009
I recently tried a circuit I found online.. Its output is square but components were easy to obtain and moreover It uses MOSFET's.. Give it a try.. It ran 90% of all the devices I tried connecting to it..




Joined Mar 24, 2008
If you want a sine wave invertor a 555 is not the way. If you don't care there are lots of ways to do it with a 555. A variation of this circuit for example.

This particular circuit uses what is called an H-Bridge. If you have 10V or more you can use MOSFET transistors, which are generally more effecient, and eliminate the zener diodes.

I don't have anything against Radio Shack, I use them for my articles (I've written several on 555 circuits). But there are better sources out there, you limit yourself if they are your only provider. Used to be you could order parts through them, but I think they've discontinued that. The real issue is price, most vendors charge around 35¢ for a 555, and the transistors are also higher cost (and limited choice).

If you need to limit yourself to Radio Shack we'll try to help where we can.

About my articles, check this out...

The 555 Projects

Bill's Index

Many are still works in progress.
Last edited: