Archive for the ‘Electronics’ Category:

2020-06-20 Facebook Groups Lack Members Rights And Admin Responsibilities

The main reason I joined Facebook was to interact with others who shared my vocation and avocation, Electronics. It’s been a part of my life since I was very young. More than five years ago I joined several FB groups dealing with Electronics. During those years I have been banned from several groups not because

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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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2017-09-20 Use LM7805 To Charge Phone?

I posted this comment to FB Arduino group 2017-09-22. “Can I use a 7805 (regulator IC) to charge my cell phone?” The output is 5 volts, which is what the phone needs to charge.  But the average smart phone will take more than 1 amp, up to 2 amps to charge quickly.  The 7805 can’t

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2017-06-08 AD Has ADP5090

Ever since I’ve been experimenting with Joule Thiefs I’ve done so with the intention of using the circuit for boosting a low voltage source to power a higher voltage circuit.  So I think this Analog Devices ADP5090 is very useful for doing just that: powering circuits up to 200 mW from very low voltage power

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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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2017-05-21 22-120 Power Schematic Errors

Posted to FB group 2017 June 8, then a copy here. I found this Radio Shack power supply on Bama.edebris.com.  Looks like someone drew it up.  I found a few boo-boos, one being the LED having a 100k current limiting resistor.  It’s not going to be bright. I wonder if BK1 thermal breaker is capable

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2016-10-26 Why Separate Power Supplies Are Needed

Peter asked a question about why is there a need for two separate power supplies for the same project.  I guess it never occurred to me to explain this simply, so everyone can understand it. I have often had to use a separate power supply for one part of a circuit, with a second supply

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2016-10-04 Joule Thief Powers Field Strength Meter

There are many circuits that are used infrequently that are powered by the usual 9 volt battery. One of these happens to be a field strength meter (FSM), which is used for detecting the power output of a transmitter such as the one a radio amateur uses. Some FSMs are very simple and use no

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2016-02-20 Charge Car Battery Faster

I needed to pick some grapefruit from the tree, and I borrowed the picker pole from a friend.  I put it in my Civic and got home, took it out and picked some ruby red grapefruit.  Man, were they Delicious! So Monday I got in the car, and CLICK!  It wouldn’t start.  Then I noticed

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2014-11-06 Other Useful Things From DX.com

I saw a few items at DX.com that look like they could be very useful. A USB power meter, with even more information in the display, compared to the somewhat lame Practical Power meter. You won’t be caught with a dying cell phone battery with this.  It’s a useful addition to your flashlight collection.  This

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