May be missing some thing in all of this. But isn't AC coming from the mains through a step down transformer going to be just as dangerous as the same voltage coming from your converter? But the step down transformer will have a much better/accurate sine wave.

If you do something dumb like latch yourself across both leads of the secondary or there is leakage to ground then your statement is probably true. But otherwise a transformer will be safer due to isolation from earth ground.

 

If you just want to play around with these circuits for learning purposes, just buy a simple 12 volt AC mains powered transformer.

It will be perfectly safe.

Buy a bunch of 1N4001 diodes, the cheapest garden variety - and have at it.

Feels like this thread went way off the rails with complicated ideas.

Thank you Sensa, you are correct.
Back to my original plan, I wanted to do the exercises and if possible, work with lower voltages. As I complete each exercise, or not, try and figure out why or why not. Measure current at different points, look at wave forms, etc. That's my best way to learn. As I started looking at the next exercise, I realized that there was going to be potentially 440 volts running around my cheesy breadboard ( I didn't know that the current would be small ), and I am about to start sticking my probes into various places.
Hence an idea to lower the voltage. Hence a new project.
Step down transformers are the easy path.
The Variac seemed a better alternative and I still can't imagine why they would be more dangerous than a transformer.
Other than paying attention to minimum voltages on data sheets, I was thinking that I could do these tasks with a far less lethal voltage. Say 12 volts AC max. And I might even try and keep the voltage at 9 or lower.

As an aside, the voltage that I am getting from pins 10 and 11 of the 4047 is 2.5.
I tried feeding it into a mosfet but I think (know) that I have something wrong.
I wish that my scope would get here so I could look and see.

 

The Variac seemed a better alternative and I still can't imagine why they would be more dangerous than a transformer.

Because they aren't isolated from the mains. A standard step down transformer is.

 

Hello,

Isolated variacs seem to exist:
https://www.ebay.com/sch/i.html?_fr...ted+variac.TRS0&_nkw=isolated+variac&_sacat=0
They are more than 3 times expensive than the non-isolated ones.

bertus

 

Because they aren't isolated from the mains. A standard step down transformer is.

I follow what you are saying and when I get past my present bottleneck, I am gonna start another thread so I can understand it better. Thank you for your cautions.

 

AC is far more dangerous than DC. YOU are not only a resistor, but also a capacitor. With DC, this effect is negligible. HOWEVER, with AC, you can get much greater currents because of your capacitive properties.

You are talking about radio frequencies that pass high currents through the tiny capacitance of a person. AC at the very low frequency of 50Hz or 60Hz causes your muscles to vibrate on and off. DC is much more dangerous because it causes your muscles to turn on continuously and you cannot let go.

Why is the OP experimenting with a 100W or more inverter instead of just 1W or less from a mains transformer?