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I have made a DC Led BULB (7 watt) which is working on 12 volts input. By the way its input voltage range is 12-48 volts DC (using BP 1601 regulator ic) Now problem is that when i gave some bulbs to an NGO members. Some of them tried to operate it on 230 volts mains supply.which malfunctioned DC LED driver circuit. Now i want to protect this 12 volt operating circuit from ac mains supply. I tried and failed !!!

I used bridge rectifier to convert ac to dc means 230 AC to 230 DC then i m unable https://electronics.stackexchange.com/editing-helpto step down 230 Volts DC to 12-48 Volts DC.

Any other way to bipass AC input!!!

like over voltage protection,surge protection,over current protection,short circuit protection etc...i want a extra protection which wrong input type protection."MAINS POWER SUPPLY Protection for any DC circuit either it is operation on 3.3 v or 5 v or 12 v input"

:-) Fixed the circuit myself.

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  • \$\begingroup\$ Why is the bulb compatible with sockets of a type that would supply 230V AC? \$\endgroup\$ – Dan D. Nov 23 '14 at 17:52
  • \$\begingroup\$ because i designed for poor people in india.B22 holder for bulb is commonly available here in cheap rates.So some unaware people try to check that if its also working in AC holder \$\endgroup\$ – Deepak Mishra Nov 23 '14 at 17:56
  • \$\begingroup\$ You can simplify my question.like over voltage protection,surge protection,over current protection,short circuit protection etc...i want a extra protection which wrong input type protection."MAINS POWER SUPPLY Protection for any DC circuit either it is operation on 3.3 v or 5 v or 12 v" \$\endgroup\$ – Deepak Mishra Nov 23 '14 at 17:59
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    \$\begingroup\$ Good grief! Thank heavens it's illegal in EU to use 230V connectors for non-230V lights! \$\endgroup\$ – PkP Nov 23 '14 at 18:45
  • \$\begingroup\$ What about a polyfuse? \$\endgroup\$ – George Nov 23 '14 at 23:31
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If you want something that blocks AC voltage use a:

  • bridge rectifier:To convert/"block" AC voltage to DC voltage
  • polyfuse: Overcurrent protection after. Should provide some short circuit protection too AFAIK.
  • transformer To reduce the voltage.

Note: The order of these components is not entirely accurate.

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You could try to add an inductor in series with a rectifier bridge at the AC side, such that it drops about 200V at 50Hz. The wire should be thick enough to not cause a significant voltage drop at DC. I suspect that the inductor will be bulky.

Do not use this with only a half wave rectifier (single diode), as the inductor might cause a huge voltage spike as soon as the diode cuts off the current.

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