it looks like the power supply suffers from start up issue. During start up, the bulb current  maybe higher than 1.7A and the output cap always need current to charge up. Soft finish circuit in the secondary side can help, because the start up time can be longer and thus the capacitive charge current will be lower. A capacitor paralled with the zenner can be used for the soft finish. Try a 10uF first, then 22uF, and see what may happen.

Thanks a lot for using PI part.

I tried as you say PI-Cochrane.. didnt work.. i does not seems to be startup problem.. i let the power supply on and then put the load on ...but still bulb dosent glow...can any of my components could be faulty? should i increase input bulk cap?

The current through the bulb could be much higher than 1.7A. Could you PLS check the load current when the bulb connected to the output.

Regards

It is taking 2amp on 13.5 volts... i have designed smps for 3 amp in PI expert and design passed.?

If the power supply works with 3A constant current Load, we will know that the isssue is caused by the load itself. Or we will know that we need to wrok on the power supply.

We need to work on power supply. I attached 30 watt bulb that takes 2.5 amp on battery. But power supply not driving that bulb. it keeps restarting... i managed started current oring with battery and power supply keeps restarting after battery removed.

I have used motor this time, stopped by hand to draw more current . power supply working with 3.1 amp. no voltage drop not much heat.............. transformer is producing little sound.

I want to use the power supply for the FAN(24 watt). Is there any way to make power supply sustain startup current for some time. FAN is not starting with power supply. ....once started power supply is capable of driving fan..

Thanks

For start up, Longer start up time and lower value output capaictor means power supply can source higher load current during start up. After start up, the board can not source more current unless you modify the transformer design and/ or use bigger device.

In what way should I modify transformer?

I used E40

Primery turns - 33-33

secondary turns - 7

bias - 7

As per PI expert.

Thank for help.

thanks

Your fan not work until the power supply has been started up, and the power supply can output more than 3.1A, about 50% higher than normal 2A load. I donot understand why you want the power supply has higher load capability. And I think you want the power supply can source more power only at start up, Am I right or not?

thanks

Yes FAN needs more than 3 amp at startup and continious running current is 2.3 amp @ 13.5 Volts.

This is what i want.....

I dont understand spreedsheet? which one? does PI expert generates it?

I guess the power should be ok if the fan not start up together with the power supply. PLS try  higher value output capacitor and test if the fan can work. If the power supply hit current limit during the fan start up, you have to modify the power supply.

PLS send me the spreadsheet that the PI expert generate it.

You told me that the power supply can work with 3.1A load and the fan not start up together with the 13.5V output. Why the system still has soem problems?

thanks

Fan taking much higher current on 13.5 volts. i slightly reduced the voltage. it is working fine now..

Thanks for the help.

Thanks a lot for using PI part