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UC3843 SMPS 12v charger, not enough power

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kg300

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Hi frinds,
I esigned a smps charger based on UC3843 chip and LM358 for 12 volt battery system. the output power requirement is about 10 to 12 Ampere and use EI-40-20 megnat core. But the problam is that the output voltage is 14.8v ok (adjustable) but no power when charging battery, only 0.25Amp power show and nothing charg.I think the fault is near the 3843 oscillator. Please can anyone solve this problam?. the circuit is hers
 

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hi i read this circuit and find some problome lm358 aera side if you send schematic then i will moor try to find what happend
 

without the schematic it is difficult to find out where is the problem
 

When used for battery charging ,remove the output electrolytic cap across the battery terminals .Thus you get 18-20VDC pulses to charge 14.6V battery
 

hi
my dear must want schematic without schematic how do i explain you what is problome and where is problome .
if you no have diagram or schematic so send me your pcb i will find and retorn you as soon as posibol other wise
no have any degision for you
thanks
bye
 
In case you feel insufficient power at output ,use a complementary stage BC547 +BC557 pair .Input drive at pin 3 and output at the battery load .
The power gets magnified to higher than 500mA ...
 

need help!!!

kg300, AOA.
I am trying to made a battery charger, and I selected diagram which you have send to EDA board,but problem is that resistor R28[820R] where it is connected you did not mention it.and second thing is that there are transistor circuit using two A733,are not working is there any circuit drawing problem? you better check it.I am waiting for your reply. 0300-4366220.

Best regards
Shahab.
 

R28 is connected with + of 2nd LED untitled.JPG one led is for CHG and second is for BT FULL
CHG.jpg
 
Last edited:
Change value of R29 and see.Its better use a multy turn varyable here to control charge rate.
I hope circuit will increase charging current.
 

Re: need help!!!

Adam Chahab said:
kg300, AOA.
I am trying to made a battery charger, and I selected diagram which you have send to EDA board,but problem is that resistor R28[820R] where it is connected you did not mention it.and second thing is that there are transistor circuit using two A733,are not working is there any circuit drawing problem? you better check it.I am waiting for your reply. 0300-4366220.

Best regards
Shahab.
Click to expand...

If leds are not working properly,try to modify according to attached schematic.
 
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