dear all,

i have created following circuit as a 12v battery charger but its output voltage is higher(some what 25v) than the expected voltage which is around 14.5V . So any body please explain is their any faults of this circuit and how to correct it..

Big thanks.

indi

 

This circuit is taken from the late Tony van Roon's website:

http://www.sentex.ca/~mec1995/gadgets/labc.htm

 

thx 4 the reply MrChips..so do u think is their any prob?

 

1. Check the pins connections of LM350.
2. Re-check all the wires connections.
3. Check Q2, Q1, do they work?
4. Does the D2 LED lighting, does c voltage of Q2 close to gnd?

 

thx..scottwang...yes i have checked several times..my doubt is that lm350 voltage regulator require proper resistance combination through it pins to necessary drop of voltage.. another thing is that variable resistant is set to adjest voltage but in my case it is no longer affect anything to the output..

 

thx..scottwang...yes i have checked several times..my doubt is that lm350 voltage regulator require proper resistance combination through it pins to necessary drop of voltage.. another thing is that variable resistant is set to adjest voltage but in my case it is no longer affect anything to the output..

How is the point 4 that I mentioned, did you measure it, and how is the LED?

 

led blinks..but once i checked the battery terminal from the multi meter the led again blinks..that means i does not has some resistance..me be it blinks for higher voltage may be 25v fortunately not burn out.

 

How is the input voltage, Vdc, DC pulse, how high?
What are you trying to charge the battery, Vdc, DC pulse?

 

input 24v dc output expected 14.5v but output was 25v..that the issue..

 

input 24v dc output expected 14.5v but output was 25v..that the issue..

Where is the Vin dc came from?
It looks like the filtering has some problems, do you have O'scope to measure the Vin?

 

Measure the voltage at the base and emitter of the BD140.

 

Where is the Vin dc came from?
It looks like the filtering has some problems, do you have O'scope to measure the Vin?

dear scottwang dc input will be given from a 3A transformer with 4 half way rectifiers..dc input has no issue it wil around 17v-24v range NOT above that..
need some help
no i havn't O'scope
thx
indi

 

Measure the voltage at the base and emitter of the BD140.

Thx for reply..so what to do with measuring above voltage..i'm not expert in electronics..any clarification please

 

Short out the C/E of the bd140, what voltage is at the output, is the led on?

 

Short out the C/E of the bd140, what voltage is at the output, is the led on?

thx..dodgy... i am actually away with it just kept it in a box..and trying to figure out the prob with this forum..you sure is not there any harm for bd140 while shorting..ok i will try..thx

 

i search that lm750 module on ISIS simulating software but coould not found..plz anybody know good software with huge database for circuit simulating..
thx indi

 

lm350 is the one in your circuit???

 

lm350 is the one in your circuit???

yep..

 

anybody plz help me..

 

Do you know which pins on the BD140 are the base and emitter?