Help required

[xyz9915]

Hi, the attachment is a schematic of SMPS built using IC TL494. The problem is that the capacitors C4,C5 get to much hot under full load. please guide what to do?

[areza]

do you have the kit? how many watts?

[xyz9915]

Thanks for reply, someone told me that low ESR type capacitors should be used because they can cope with the high frequency ripple.
so please guide which where to find such capacitor observing the ESR & high temperature stability.

[areza]

hmm, low ESR caps, well difficult to say where you can find them , its not written on the caps and seller dont care,

need to know construction details of the transformer, also the power lavel,

[Tahmid]

Hi xyz9915,

C4,C5 should be low ESR type. To measure ESR, you may have an ESR meter or you can find out from the manufacturer's website according to the series number. Calculation is difficult and not practical. I have collected ESR meter from EVB company of Portugal. It costs 50 Euro and it is giving excellent service.

A probable problem in your circuit is that, you have not used an inductor at the input. Please use this. If you use inductor, higher ESR caps will also withstand for some time and may not be destroyed immediately.

In your circuit, R15 is not required.

Thanks.

[Tahmid]

Hi xyz9915,

I have attached the picture of my ESR meter.

Thanks.