Archive for the ‘computers’ Category:

2017-09-23 Cellphone Charger Secret Circuit

Posted to FB Arduino group Sep 23 Mbihi Oliver Four hours is twice as long as 2 hours with the correct charger.  Here is a secret many don’t know:  Smartphones don’t necessarily charge at maximum, especially if they’re charged by a charger not made for their phone. Smartphones often have a sensing circuit that checks

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2017-09-19 Giant ‘Analog Meter’ For Clock Display 

FB comment “Brilliant!” Preet Sangha said, and I agree, but since I have a hard time seeing small meters across the room, I thought up another, bigger meter.  How about this? Instead of meters, use a printout of a meter face, full page size.  There will be one for each hour, minute and second.  These

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2017-09-10 How Long Can An Arduino Circuit Last?

My answer to a FB Arduino group question on Sept 17 Dan Rogers has the right idea.  The protoboard, with all the holes in it, was never meant to be permanent.  The contacts in each hole lose their springiness as they are used to hold wires.  The contacts can become intermittent after awhile.  As time

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2017-09-01 Automated Gallows – Arduino 

Suggestion for project on FB group Arduino Projects – Sept 17 Automated Gallows! A motorized winch adjusts noose. Asks for three officials to each press confirmation button. Has an emergency abort button. Counts down 5, 4, 3, 2, 1… Pulls the trapdoor latch! Monitors heartrate until no sign for 5 minutes Lights up sign “Execution

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2017-08-27 A 555 Is Easier And Cheaper Than a PIC

From a FB group post. “primitive transistors” I think that’s ironic.  The 555 makes the design easier for the builder.  It has all the parts so the builder doesn’t have to build from scratch.  Like making a cake using Betty Crocker’s cake mix instead of flour, eggs, etc, and no need for a recipe.  It’s

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2017-08-06 Seeing Digital Signals

From FB post about Arduino driving a ‘HC595 chip. You don’t need an oscilloscope to see digital signals.  If you slow down the speed, you can see what’s happening by looking at LEDs.  Everything is digital, just on or off. Plug two red LEDs, transistors, and current limiting resistors for LEDs (330 ohms), and for

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2017-07-12 It Worked!  Arduino Pro Mini Programmed

This homemade PS is smaller than an ATX PS, but the best thing is it’s quieter, because no fan is runningThis homemade PS is smaller than an ATX PS, but the best thing is it’s quieter, because no fan is running.

2017-06-01 How To Disable 5V Regulator?

I’ve been getting PC boards that have all the chips operating at 5 volts, but the input voltage has to be between 7 and 12 volts.  The board has a 5 volt regulator on the board, and often it is a surface mount chip.  But I have dozens of 5 VDC, 1/2 amp AC adapters,

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2017-01-18 Simulating An Analog Meter

A detector or discriminator in an electronic device might need to be adjusted to a very few points on a scale of a hundred or more points.  A digital indicator typically indicates only a fraction of that, possibly 16 points.  This is why the analog meter is still useful: it can indicate a small change

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2017-01-17 

From email sent by Peter, 2017-01-17 Good to hear from you, Peter.  I forgot about telling you that last year, I wasn’t able to read a message you sent me.  I don’t remember why. I apologize for not replying. I wrote this up in a blog, but the blog isn’t accessible right now.  So I’m

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