to get my rechargeable led torch running only from mains

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Nirmalath Kevitiyagala

Joined Jan 7, 2018
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i have this simple led circuit which i need to run only with mains supply, i removed the battery and plugged in suddenly the led was dead, i want to know whether batteries are working as voltage regulators and also if i remove the battery what will be the resistor i need to add series to main led.WP_20180107_22_14_09_Pro.jpg
 

ian field

Joined Oct 27, 2012
6,539
i have this simple led circuit which i need to run only with mains supply, i removed the battery and plugged in suddenly the led was dead, i want to know whether batteries are working as voltage regulators and also if i remove the battery what will be the resistor i need to add series to main led.View attachment 143203
That is a; "wattles dropper" circuit which violates the terms of this forum - no isolating transformer and most of the circuit live. you shouldn't mess with it unless you really know what you're doing!!!

The capacitive reactance is a high impedance relative to the load, so it vaguely resembles a constant current source. I'm guessing its calculated for enough current to run the LED *AND* charge the battery - the battery essentially acts as a shunt regulator. you could try a big chunky Zener.
 

spinnaker

Joined Oct 29, 2009
7,837
i have this simple led circuit which i need to run only with mains supply, i removed the battery and plugged in suddenly the led was dead, i want to know whether batteries are working as voltage regulators and also if i remove the battery what will be the resistor i need to add series to main led.View attachment 143203

Why on earth do you want to run your flashlight form the mains? You would be defeating the whole idea of a flashlight. Just use a lamp for Pete's sake!

Another solution looking for a problem. It just bewilders me as to why people seek to complicate their own lives.
 

ian field

Joined Oct 27, 2012
6,539
Why on earth do you want to run your flashlight form the mains? You would be defeating the whole idea of a flashlight. Just use a lamp for Pete's sake!

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A lot of people ridiculed the idea of a solar powered flashlight - apparently oblivious to the fact solar power can charge the battery for when there isn't any.

Why the TS wants to do away with the battery is anyone's guess, I cant think of any way it would be better - but the TS seems to know different.
 

spinnaker

Joined Oct 29, 2009
7,837
Why the TS wants to do away with the battery is anyone's guess, I cant think of any way it would be better - but the TS seems to know different.
Or maybe not. There are plenty of people that come here that already have a solution that are looking for a problem.

Besides the circuit proposed violates TOS.
 

bertus

Joined Apr 5, 2008
20,329
Hello,

The proposed circuit does indeed violate the ToS.
Both the transformerless powersupply as leds to mains come into play.

Bertus
 
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