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kuku • Jul 9, 2008

Zener fails in transformerless power supply

Hi am using one transformerless power supply in which capacitor reractance is used to decrease the mains voltage and zener(10 volt 2 watt) as regualator its about10 volt and load is of 50mA.
But the problem is that some times zener fails what could be the reason ?
balaseven • Jul 9, 2008
Hi kuku,

Make sure that u have reverse biased the ZENER diode.Moreover,your expected regulated output should be same as zener diodes reverse breakdown voltage or zener voltage.For example, If your expected regulated output is 10V,you should select diode which has zener voltage as 10.
Hope this helps u.
kuku • Jul 9, 2008
Hi BibB,
Thank for that.
But everything is ok.Then also it fails.
why dont ya use high-ampere diode say HV135 or simply increse the capacitor load
balaseven • Jul 10, 2008

whats your input voltage,is it 230V AC?
i think,you r trying to get the step down transformers's funtion without using transformer,isn't it?if you dont mind,post your circuit,i will analyze and try to tel the reason.
kuku • Jul 11, 2008
hi Sourav,
Thanks for reply. Actually i think its not taking so much power with calculation its hardly reaching 1W.
hey if u need DC supply then use a bridge rectifier as it devides the load between the diode,if u wanna regulate the AC voltage then diode is not suggested but why u aint using a transformer???...its the best way to regulate AC...

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