Archive for the ‘Electronics’ Category:

2020-09-05 Capacitive Dropper Failures In 240 VAC countries

From a comment I left in Big Clive’s youtube video https://youtu.be/jgaCYRc1-og In the past I’ve seen Clive having to replace “used up” capacitors in the ‘capacitive dropper’ circuits of low cost line operated devices. The problem seems to be common in other countries but here in the US I haven’t seen any problems with the

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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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