Driver transitor for LED emergency light

[manojworld]

same problem i want to charger faster to the battery it tahes around 48 hrs to charge

Hi

My knowledge in electronics is limited. I built this circuit.

I had a problem. The variable 2k2 has one point on negative and other point and middle point common with adj LM317 and collector of BC548. When i do this bridge, capacitor and LM gets really hot.

Then in changed and made on point of variable on negative other point on adj of LM317 and middle point on collector of BC548 and everything worked perfectly OK.

Am i reading the schematic wrong or what?


Secondly we are having 6-8 hrs loadshedding (power cut) per day in our country and my 6v 4.5AH battery gets fully charged in 20 hours, can i make some changes to it so that it can charge in just couple of hours?


Thanks

same problem i want to charger faster to the battery it tahes around 48 hrs to charge

 

[msn1270]

What is the part number or where do we get the While LED?

 

[abhaykanade]

I have also having promble of charging of battery i see LM vout volt is ok but amp/current is very low. Give me changes of circuits.

 

[rs.led]

T2 needs a reasonable abject bent to accomplish as a switch. With 1k in alternation with the no-load bent of the LM317, it's accepting at a lot of 2mA. At the affliction case saturated accretion of 10, this would accumulation 20mA to the load. Obviously the transistor getting acclimated is accomplishing bigger than this.







__________________
LED Flashlight

 

[irfanulla]

HI as again - this is the first post and I have been searching for a circuit since I have a strip of LM317HV's and a few transformers lying around -

what would be the quick charging method - is it pumpin in more current or more voltage?

I am a mechanical engineer and low on electronics knowledge - but this circuit is very interesting and I wanna build this ASAP - again there are so called fast chargers in the market - what do they actually do to get the batteries charged faster - I have read else where that we need 1/10 th of the rated current of the battery to charge it - how much time does it require that way, also how do we calculate the estimated backup it can provide.

RGDS
IRfan

 

[cisco]

Indication for battery charging ??

Hi,

I assembled the circuit the way it was shown in the diagram. It is working fine.
Can anyone help here to set a LED which shows the charging progress and turn off when the battery get fully charge?

Thanks in advance.

 

[dsrini73]

Please send the PCB and Schematic details to dsrini73@yahoo.com

 

[cisco]

Hi,

Thanks for your response.
The circuit detaila are at the below mentioned link:

Free Electronics Projects-Electronics circuits and hobby designs diagrams - Free Electronic Circuits & Electronic Designs » Automatic LED Emergency Light

witing for your response.
Thanks

 

[rrayamajhi]

Hi

I kindly request you to send me PCB layout for emergency LED light.

Thank you

Rajan
rrayamajhi@yahoo.com

Hi


I've built **broken link removed** circuit for LED emergency light which turns the LEDs on when there is power failure.

It use BD140 pnp transistor for this purpose. I have 60 LEDs in the panel which are best operated at 3.25 volts drawing 950 mili amps.

BD140 only gives 3V and max current of 450 milli amps (without any resistance attached to LEDs) so the LEDs don't glow as bright as they should.

I tried BD176 but the results were worse then before i could only deliver 250 miliamps (without any resistance)

I then trided TIP42c, it gave 650 mili amps @ 2.98 volts without applying any reistance.

What would be the best transistor in the circumstances which could deliver the desired voltage and current.



PS: My knowledge in electronics is just basic.


Thanks in advance
Waseem

 

[Rohan123]

The circuit does have a flaw; the transistor base bias assumes that the voltage across C1 goes 'low' when the power fails. But the only load on it is the no-load current drain of the LM317. I would add a 560 ohm 1/2-watt resistor across C1, and would change R15 to 270 as well.

And of course I would use the LED resistors as shown in the original circuit. Why leave out resistors? Do you prefer building things that don't work?

i agree here. the ckt does have a flaw. the base of BD140 should pulled down to ground when mains power fails. so i connected a 100K resistor between the base and the ground. when rectifier vtg is available, the BD140 base remains high and BD140 does not conduct. Incase of power failure, BD140 gets negative base bias thru 100K and conducts and LEDs glow...

 

[Rohan123]

HI as again - this is the first post and I have been searching for a circuit since I have a strip of LM317HV's and a few transformers lying around -

what would be the quick charging method - is it pumpin in more current or more voltage?

I am a mechanical engineer and low on electronics knowledge - but this circuit is very interesting and I wanna build this ASAP - again there are so called fast chargers in the market - what do they actually do to get the batteries charged faster - I have read else where that we need 1/10 th of the rated current of the battery to charge it - how much time does it require that way, also how do we calculate the estimated backup it can provide.

RGDS
IRfan

someone will need to take special elex classes for u to answer all those questions...

 

[Rohan123]

Hi

My knowledge in electronics is limited. I built this circuit.

I had a problem. The variable 2k2 has one point on negative and other point and middle point common with adj LM317 and collector of BC548. When i do this bridge, capacitor and LM gets really hot.

Then in changed and made on point of variable on negative other point on adj of LM317 and middle point on collector of BC548 and everything worked perfectly OK.

Am i reading the schematic wrong or what?


Secondly we are having 6-8 hrs loadshedding (power cut) per day in our country and my 6v 4.5AH battery gets fully charged in 20 hours, can i make some changes to it so that it can charge in just couple of hours?


Thanks

yes, increase the charging voltage thru the variable resistor.

 

[louisfung99]

Hi, I would like to ask if you can send me the layout and schematic for this project?
Hope it is still with you. thanks
louisfung99@yahoo.com

Hi to all interested in building the circuit,

I have designed a PCB including the changes as suggested: 560Ω/0.5W resistor across C1 and base resistor of T2 reduced from 1KΩ to 270Ω. Additionally I put four 47nF capacitors across each connection of the bridge rectifier. (makes the LM317 happy) The transformer used is a Gerth print transformer type 421.1-9 with max 556mA.

The entire design is purely single sided.

The design can be used as one single board or might be split into two as outlined in the dimension drawing. Connections between boards are marked A-A1 and B-B1.

Everybody interested in the layout (and schematic) is welcome to obtain it free via email. It is made using Eagle v. 4.16.

Here's a screenshot of the board.

Regards

Hans

 

[louisfung99]

Hi,

May have the schematics and pcb files as well.
Hope you still have it.
thanks,

louisfung99@yahoo.com

I kindly request you to send me PCB layout for emergency LED light.

Thank you

Rajan
rrayamajhi@yahoo.com