Hello to forum. I have few weeks try to make a classD amp using tl494 PWM chip.
i'm try booth schematics
and i think is waste of time. First schematic i think they have problem to phase split stage and second schematic is never work.
when i run the circuit about 40vDC everythink works fine but if i increase voltage about 80/100vDC, amp works for 5-10 minutes and output fets are blown up.
i Cant find a formula to calculate the output inductor (LC filter), informations about inductors arround internet, forums etc are incorrect and i'm searching a simple schematic using single TL494 with descrete parts or TL494 with hi low driver such IR2110 or something.
I have spice model for TL494 on multisim but i cant find a schematic to test it.
Thanks a lot.
i'm try booth schematics
and i think is waste of time. First schematic i think they have problem to phase split stage and second schematic is never work.
when i run the circuit about 40vDC everythink works fine but if i increase voltage about 80/100vDC, amp works for 5-10 minutes and output fets are blown up.
i Cant find a formula to calculate the output inductor (LC filter), informations about inductors arround internet, forums etc are incorrect and i'm searching a simple schematic using single TL494 with descrete parts or TL494 with hi low driver such IR2110 or something.
I have spice model for TL494 on multisim but i cant find a schematic to test it.
Thanks a lot.
Use 15uH and 1uF for the output filter. If your "1mH" is 1 micro Henry, it is far too little (too high circulating currents) and if it is 1 milli Henry, it is far too much and your bandwidth is too low.
Yes, it is difficult to avoid conduction overlap in the power switches without a IR2110 or similar. That may be what is killing your power switches together with a possibly very heavy output filter.
Such "discrete" class D implementations are for those who insist but it may be a great learning experience. You are not the first to struggle with making it work reasonably well. Even the push-pull drivers are not easy to design and this is why integrated drivers are interesting if you don't go for a fully monolithic implementation.
Yes, it is difficult to avoid conduction overlap in the power switches without a IR2110 or similar. That may be what is killing your power switches together with a possibly very heavy output filter.
Such "discrete" class D implementations are for those who insist but it may be a great learning experience. You are not the first to struggle with making it work reasonably well. Even the push-pull drivers are not easy to design and this is why integrated drivers are interesting if you don't go for a fully monolithic implementation.
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here is the link of amp.
DIY 500W Class-D TL494 Switching Amplifier - Electronic Circuit
about L1 says 22-35uH (micro henries) and schematic says 1mH (i dont know if is micro or milli but i agree with you about inductance)
Friend of my is running that amp with +100vDC without problems for he's fullrange speakers, each module per speaker for mobile DJ applications arround 2 years. means full power arround 8-10hours.
He use diy inductor from EI33 transformer with 1uF cap for the low pass LC filter but the transformer is was wrapped by a another friend of mine who can not find him anymore to ask him how to calculate coils and that's where my problem is.
the circuit as I see in the simulator (multisim) works well and the hi lo bridge also. The whole problem is created on the output coil when I put the IR2110 driver or the like again will cause me a problem. I have feritte's available from behringer's powered console (PMH-5000) and many transformes from pc switching power supplies to use also.
My oscillation is arround 100kHz. 110kHz measure my multimeter on pins 9/10 of TL494 on idle mode and gates of IRF640 also on idle mode.
I tried building too,the first one was gave little humming, but something was not right (Every connection was good, and also every of my component i used was usable and good,) The second scematic straight up wrong. At the ic it is wrong, even the ic not switching with that scematic, and the driver part of the scematic is a complete mess that dont make much sense. Im strugling a bit, but i made a new plan, only the driver part missing (i did hooked up the ic collector to bjt pair that runs on 10-20Volts, i have 10Volt no problem, and that to 22ohm resistor, and it did go straight to the mosfets, i got a little volume so i just have to figure out the driver part to boost voltage for the mosfets
, probably a p-channel and n-channel mosfet will do the work for that)