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Simple Cheap APO Auto Power Off homebrew circuit, for anything you can imagine

Do I really need a foreword here ?? come on all people forget to turn off stuff
It drives me nuts to start a new day, and first thing I see is the soldering iron still powered on from last night,
it is a waste of power, waste of good life time of the tip and anything else it consist of. Darn it..
Solution: make you own little halve day project, a small cheap and simple APO,
I made if from as standard parts as possible, no programmable parts needed, no C-code needed.

Working Prototype, OK lets explain all the hardware and in great detail.

as simple and as cheap as I could come up with. The most expensive part is the solidstate device, from ebay about 1$
just search Omron Solidstate and you find plenty, go for the 12V version as i did, then you dont need another extra series resistor.

bottom looks like shit, sorry about that, this is no art work, just a working prototype

The APO Auto Power Off schematic. No need to add 3 x 470k in parallel as i did on the pictures, it was just some experiments, not needed.
The 100uF capacitor on the 10V supply is not critical, but should be in the range 47-220uF,
too little you get ripple and maybe even resets, too much and the power on reset will not work.

please read the 4060 datasheet, it explain how this IC works, The important stuff is the oscillator values CX 47uF, RX 10k, Time = 0.47 sec
I use the output Q14 so it is dividing the input by 16384 (0.47 secs x 16384)/60 = 128 minutes, is a bit over 2hrs
Use Q13 for 1hr, and so on, or change the capacitor value.

pinout and functions of the 4060
Reset is pulsed high during power on, this reset time is a bit critical for the feature wanted,
it must not be too slow, compared to the charge time of supply capacitor
The values shown works perfectly fine with a good safe margin.
So lets say you sit and work, the soldering iron turns off, then just power it off and on again, for another 2hrs of power.

connection of the prototype to the input of my soldering station was super easy, it is so small it fits inside almost anything.

last check before isolation protection and assemble.

Last thing : add a label, so others will not complain about "random-failures" that is mysteriosly solved by recycle the power :-)


Thomas Scherrer OZ2CPU 2018
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