sunil21
Advanced Member level 4
As a first step to build a Half Bridge , I assembled one with IR2153 and an ATX transformer.
with the frequency set to 40khz (RT - 18k , CT - 1nf) , it was outputting around 26 Volts
2 mosfets - 4n60 (FQPxx... 2.6 amp 600v). initially I had two Bulk caps 100uf/250 volts. I connected the output to load, over 1 amp and all seemed okay. (mosfet , Transformer all very cool). Then I changed the Input capacitor. I made a new input part. connected 1x150uf/450v capacitor followed by two 3.3uf/350v in series. for few days / few testing this was working okay . Then one day during working I heard a sound. No output.
I checked - both mosfets gone. IR2153 gone .. IR2153 VCC- GND is short. so i bought new IR2153 and Two 4n60 . connected a 60w lamp before the bridge . I turned it on and gone again... I checked both Mosfet gone , upper mosfet gate resistance is gone ( resistance value infinity). IR2153 still seemed to work . I connected a 56k (RT) and 4.7uf(CT) and connected two LEDS and they are alternately blinking.
In flybacks when Mosfets die (my cases) , I usually found the Drain-source short (continuity in multi meter). But here The Gate-Drain is found short. So with the 150uf in the input I heard connecting a lamp before it wont save the mosfets.. And today I replaced the burned gate resistor. and mosfets (2X2N60). to the one end of the transformer I have the 1uf/250v capacitor and to the other end I connected a 60w incandescent lamp. Turned it on - again gone... both mosfets... G-D short (no reading for even body diode) What could be the reasons.. so to at least save my mosfets where should i connect the 60w lamp..?
with the frequency set to 40khz (RT - 18k , CT - 1nf) , it was outputting around 26 Volts
2 mosfets - 4n60 (FQPxx... 2.6 amp 600v). initially I had two Bulk caps 100uf/250 volts. I connected the output to load, over 1 amp and all seemed okay. (mosfet , Transformer all very cool). Then I changed the Input capacitor. I made a new input part. connected 1x150uf/450v capacitor followed by two 3.3uf/350v in series. for few days / few testing this was working okay . Then one day during working I heard a sound. No output.
I checked - both mosfets gone. IR2153 gone .. IR2153 VCC- GND is short. so i bought new IR2153 and Two 4n60 . connected a 60w lamp before the bridge . I turned it on and gone again... I checked both Mosfet gone , upper mosfet gate resistance is gone ( resistance value infinity). IR2153 still seemed to work . I connected a 56k (RT) and 4.7uf(CT) and connected two LEDS and they are alternately blinking.
In flybacks when Mosfets die (my cases) , I usually found the Drain-source short (continuity in multi meter). But here The Gate-Drain is found short. So with the 150uf in the input I heard connecting a lamp before it wont save the mosfets.. And today I replaced the burned gate resistor. and mosfets (2X2N60). to the one end of the transformer I have the 1uf/250v capacitor and to the other end I connected a 60w incandescent lamp. Turned it on - again gone... both mosfets... G-D short (no reading for even body diode) What could be the reasons.. so to at least save my mosfets where should i connect the 60w lamp..?