Archive for the ‘Power supplies’ Category:

2019-09-07 2 LED Lights On One Supply

I got some 10W warm white LEDs, and I have some cool white LED strips and they’re both running in parallel off the same 12V supply. But they’re not the same voltage so I had to do some experimenting. The 10W LED is actually a group of 3 by 3 in series – parallel on

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2018-12-12 LM78xx Linear Regulator Disadvantages

from FB group Building Transistor Radios 2018-12-13 Joseph Rotello I agree with some of your claims. But I know far more about 3-terminal regulators than you think. First off, your claim that they are more efficient is unproveable. There are linear PSes that are more efficient. That was the reason LDO regulators were used. You

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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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2017-06-01 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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2014-10-07 Fast Charging From Car’s 12V Socket

Earlier this year I bought a cheap cell phone charger for plugging into the car’s cigarette lighter socket.  It works, but it’s s-l-o-w.  I can drive for a half hour with the cell phone plugged in and it says it’s charging but it only charges a few percent.  As a result, I don’t use the

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2014-05-21 Laptop AC Adapters

A friend of mine has taken on the task of finding replacement AC adapters for two laptops, and I thought that I could repair the broken cord on one. But I tried to take the brick apart and damaged it beyond economical repair, so I resorted to the ‘Net to find replacements.  He gave me

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