Above I wrote that Edwin was also an Electronics Designer Tool from the makers of Tina. But I need to correct that. It is called Edison that is a simpler graphical version from the same makers that made Tina (DesignSoft). Although Edwin also is an existing Cad designer tool for Engineers, it is a completely different program.
And I like to add that the more enhanced (more expensive) version of Tina also supports Developing in VHDL !

Likes(0)Dislikes(0)

You're Welcome Robert. (About my 'Pretty good shape' : In Januari 2014 they defibrillated my Hart with normally Dangerous High Voltages in our Local Hospital. So it all is a matter of opinion).

Safety above All. And mostly above the 42 Volt levels. Because if I'm correct that is the level at which Low Risk Voltages start to become Higher Dangerous Voltages. It means for an Electronics Engineer knowing how to build it the correct right way. NEVER without Fuses or saving on the right material or the right components. Good Isolation is a part of that. Not only to guarantee good working circuits but also preventing secondary hazards like Fire or RF emissions etc.

Next excerpt from the Wikipedia about Safety and Voltages explains it very precise I guess:

[Extra-low voltage (supply system) AC < 50 Vrms DC low risk]
The numerical definition of 'high voltage' depends on context. Two factors considered in classifying a voltage as "high voltage" are the possibility of causing a spark in air, and the danger of electric shock by contact or proximity. The definitions may refer to the voltage between two conductors of a system, or between any conductor and ground.
Voltages greater than 50 V applied across dry unbroken human skin can cause heart fibrillation if they produce electric currents in body tissues that happen to pass through the chest area.[citation needed] The voltage at which there is the danger of electrocution depends on the electrical conductivity of dry human skin. Living human tissue can be protected from damage by the insulating characteristics of dry skin up to around 50 volts. If the same skin becomes wet, if there are wounds, or if the voltage is applied to electrodes that penetrate the skin, then even voltage sources below 40 V can be lethal.

But since we even can burn ourselves from a cup of burning hot tea, it doesn't mean we now stop drinking to be safe.
Cheers.
Albert.

Likes(0)Dislikes(0)

I agree - there are no guarantees. We have to be as careful as possible. It sounds like you are in pretty good shape.
I downloaded the datasheet of the X2 capacitor but haven't studied it yet. Thanks for the article and info.

Likes(0)Dislikes(0)

Hi Robert, I understand your concerns. But as you say the "Optical Fan Controller" is isolated too. It is boxed into the sturdy adapter case. And placed just under the ceiling were no one can touch it.
And even every transformer has two power pins that must not be touched at their Primary side at any circumstance. And when a child would take my Adapter out of the Wall Outlet to play with it there in fact would not be any real danger left!
Just two days ago I opened up my Sony Cassette Dolby Tapedeck just to exchange the old rubber snares and grabbed unattendedly the Primary side of the Transformer side. It gave me a Hell of a shock but I let go at the same time. And I still remember when I as a Child out of curiosity put the 12 Volt motor wires into the 220 Volt Wall Outlet/socket. (it was still 220 Volt AC at that time). The Motor worked very fast for a very short moment and I survived. And there is no way to be sure that a child isn't going to do the same by poking around in things by using a metal screwdriver. Transformer or not.
Albert.

Likes(0)Dislikes(0)

The main problem is when some curious children start messing with things. As long as a child can't get into the box, it would be safer, but transformers aren't that expensive. You can make your own transformers also. I like to make things as safe as possible, especially if a child could get ahold of the device.
You are right that even with SMPS's there is no guarantee you won't get hurt, but the isolation makes it a safer device.

Likes(0)Dislikes(0)

Good project, thanks for sharing. I was not aware of the "Tina" simulation software thanks for the tip. I will have a closer look at it. I have been using an old version of Multisim for simulation and SPlan when I need to just draw a circuit diagram. As you correctly said, Electronic Repairers need to do some circuit design time to time. It is fun and also good for understanding how circuits work

Cheers,
Gerald

Likes(1)Dislikes(0)

One thing I like to add concerning the users Safety is the fact that the X2 Special Safety Capacitor still could be charged after the adapter is just pulled out of the Wall Outlet. Which doesn't concern the controller circuit while it operates, and only uses some extra power while it functions. And I am refurring to an extra discharge Resistor of about 1M Ohm one could add over this Capacitor to prevent this from happening. I added the 1 Mohm to the prototype version shown but after translating my Tina circuit into an English version it somehow disappeared from my final circuit unattendedly.
Mea Culpa!
Albert.

Likes(0)Dislikes(0)

Hi Robert,

Of course there must be thousends of different NE555 circuits. But at the time I made this circuit and Simulated it I could not find ONE single circuit that worked Optical. And even the commercial ones used one of the Switch wires and weren't Optical at all. In fact the capacitor (C5 4.7uF) significantly minimizes this presented circuit and is probably a very, very old Electronics Trick to enable the Triggering the way I needed it here. It is used as a kind of memory cell and makes this circuit very reliable at the same time. And I know you are kind of a 555 Wizard from what I've read on some older Posts. And if you build these kind of small devices without using a transformer there is no real danger if you keep everything in a closed sturdy housing and use the right precausions like fuses and the right safety parts, nothing can happen. I also used 0.2 mm wire for some of the low voltage (9 Volt) circuit connections. So even if something other then the fuse would burn out, it would also be a kind of safe circuit breaker. And most new houses like my brother's have all TWO safety Earth leakage circuit breakers.
(One for the higher Power washing machine group, and a second for the normal groups. With their different Earth current values).
But that said it is just as safe as your ‘unsafe’ pc power supply for laptop or desktop that even if it is boxed in a plastic housing, isn’t made for outdoor use!
(When it gets wet it is lethal too!). And the Funny thing about those PWM Controlled Power Supplies is, that if something gets defect the Primary fuse is often still just fine!
Cheers,
Albert.

Likes(0)Dislikes(0)