Recent Posts

1

Beginners / Re: Shocker

« Last post by xrunner on Today at 12:40:45 am »

I have a racoon who kicks that feeder around and turns it over etc.  ...

You have "a" racoon as opposed to several?

Like John Wick, a racoon is an animal of focus, commitment, and sheer f*cking will. It will go after any food whatsoever any way it can and won't give up. I know becasue I've tried to feed local cats. But if you have a single racoon you can trap it and set it free many miles away. It might not come back, or it might, but it's worth a try.

2

Projects, Designs, and Technical Stuff / Re: 200 Minute Timer Circuit Design Help – 8A 120VAC Load.

« Last post by JJ_023 on Today at 12:39:37 am »

Divider off the mains frequency perhaps - more accurate than RC. 200 mins = 12000 secs. CD4020 & a couple of diodes to stop when bits 12 and 13 go high ( 12,288)

Keep in mind I am still somewhat of a beginner.   The way I understand what you wrote is that you would use the 60 Hz mains as a clock that you would then use a counter to keep track of time.   When it reached  12000 it would stop.  This is a great solution for this part of the equation.

 Is this correct?

The part I don't get is how do you use a couple of diodes to stop.  I don't have any real experience with counters or dividers.

Thank you in advance.

3

Other Equipment & Products / Re: What are the chances these are real?

« Last post by BillyO on Today at 12:33:30 am »

Some discussion here:
https://forum.allaboutcircuits.com/threads/power-supply-kit-supply-voltage-on-tl081.128351/
https://electronics.stackexchange.com/questions/520653/how-to-find-a-pin-to-pin-replacement-for-tl-081-but-with-higher-vcc

Maybe the negative rail voltage can be reduced?

That's option 4 and not too hard to do, but you'd still need a negative rail of about 3V so that would just save 2V - not really enough but would certainly extend the life of the OpAmps.  You'd still have to deal with pass transistor.  The operating envelope has the possibility of it dissipating 100W.  That's it's AMR.  SO all in all a PS living on the edge.  I'd like to have it "safe at all possible speeds" (Sorry Ralph) 

4

Beginners / Re: Shocker

« Last post by aeberbach on Today at 12:32:01 am »

A zap from the past...

https://schematicsforfree.com/files/Misc/Home%20Electronics%20%26%20Appliances/Misc/Electronic%20Mousetrap%20ETI%201524.pdf

But doesn't the raccoon get trapped in the same way as the cats would? (I don't know much about them, no raccoons locally)

5

Buy/Sell/Wanted / (AU) Obsolete NS405/NS455 display/terminal management processor semis wanted

« Last post by aeberbach on Today at 12:26:47 am »

Does anyone have any lying about? I am interested to experiment with one of these but don't feel like paying the $80 or so US eBay sales will cost me.

6

Projects, Designs, and Technical Stuff / Re: 200 Minute Timer Circuit Design Help – 8A 120VAC Load.

« Last post by JJ_023 on Today at 12:26:15 am »

Run's on two lemons.

Adjustable Wake-Up Period: 250ms to 39 Days

https://www.analog.com/media/en/technical-documentation/data-sheets/2956fa.pdf

Definitely a neat little chip thank you.

7

Microcontrollers / Re: microcontroller Interrupt circuit

« Last post by Doctorandus_P on Today at 12:25:51 am »

Usually there are a lot of ways in which ISR's can be triggered by software, but they tend to have various side effects. With your method, you loos an I/O pin, and when it's shorted it does not work at all. Another method is to pre-load a timer and let it overflow after command.

8

Other Equipment & Products / Re: What are the chances these are real?

« Last post by thm_w on Today at 12:25:48 am »

Some discussion here:
https://forum.allaboutcircuits.com/threads/power-supply-kit-supply-voltage-on-tl081.128351/
https://electronics.stackexchange.com/questions/520653/how-to-find-a-pin-to-pin-replacement-for-tl-081-but-with-higher-vcc

Maybe the negative rail voltage can be reduced?

9

Projects, Designs, and Technical Stuff / Re: 200 Minute Timer Circuit Design Help – 8A 120VAC Load.

« Last post by JJ_023 on Today at 12:25:09 am »

Thank you for the suggestion on 74HC4060.  I tried to look it up but almost every place is out of stock.  I try to avoid EOL chips.

The 4060 should be very much alive from multiple sources.
You may have meant the 74hc5555, which is single sourced, and now EOL? (Tho Rochester show ~500,000)
The 74hc5555 has good data, and is operationally very close to what you ask for.

"The chip is not repeatedly triggered, meaning that in the time between it is triggered and resets, it will not respond or keep track of any other falling signals from the external controller."

 So this would prevent the user from stopping the cycle if that need arose.  Unless I am misinterpreting something.

The stop on same button feature is rare, so you would need to do that in separate hardware.
Most common would be a simple RC from the trigger button to reset, so a long press would stop.

If you want a true toggle button,  you would use a D-FF with Schmitt clock, and probably a RC POR reset and the timer reset.

TI have a new family of 74HCSxx parts, that document Schmitt on every pin.
Nexperia 74LVC parts also mention Schmitt pins.

Release of new logic families shows MCU’s have not entirely replaced logic.

I probably made a mistake and looked at the wrong chip.   I just looked at the chip again and see that a bunch of it is in stock.   Thank you for pointing that out.

All the suggestions that you make as well as other community members really open up the possibilities for me and expand my knowledge as to what is out there.   For that I am truly grateful. 

10

Buy/Sell/Wanted / Re: Looking for HP Plotter Pens (old and no good also fine)

« Last post by Tony_G on Today at 12:19:59 am »

Thanks for the video - In the thumbnail image you can see that things aren't really lined up well - I wonder if that is because of the length of the pens or if the adapters are too loose.

If I ever get this 845AB off my bench I might give the Stabilo/Sharpie cut down thing a try.

TonyG