Hi everyone, I have built a Square wave DC/AC Inverter. It runs at 60 Hz, 130V but it's only a Square Wave ,so I don't dare run any delicate electronics on it, just lights. My electronic skills are at the beginner/intermediate level, I can build circuits from schematics and breadboard with some proficiency.
I have attached two diagrams of the square wave circuit which drives a basic Mosfet Output stage. A very stable Square wave is generated by the 4069 Cmos Hex Inverter then fed to two pairs of High current Mosfets. This combination works Great!
I wanted to improve on the Inverter by adding a PWM circuit to achieve a Modified Sine Wave so I can run virtually anything on it. I have also added a schematic of a PWM circuit I found on the Internet. Its an ingenious design using Two cascaded 4017 Decade counters, achieving frequency division and a very nice wave form, also a diagram of that.
I first built the PWM circuit on a Breadboard and verified that it does produce the specified wave form.
Then I built the circuit onto a PCB. In doing so I basically put the PWM circuit just after the Output of PIN #2 of the 4069, grounded out PIN #3, then put the Buffer Transistors TR1 & TR2 , 10K & 1K Bias Resistors to the end of the Diode Junction Outputs.
I had to modify the Output of Square wave generator so that it produced a Frequency of 1.086 KHz ,this frequency is sent to the Two 4017's which have Ten Outputs each for a total of twenty, which act as Frequency Dividers. Theorecticaly a Input frequency of 1200 Hz would give you a final Output frequency of 60 Hz. For some reason in my actual circuit, I need an Input frequency of 1086 Hz to have a final Output frequency 60 Hz.
I have included a screen shot of the wave form captured on my Laptop Oscilloscope.
Now the BIG problem is that when I remove my Original Square wave generator and replace it with the New PWM Square wave circuit in place of it, when I turn the Inverter ON, it blows a Mosfet in the Output stage, and I have to quickly turn the Inverter OFF. This is what is confusing me. I know for a fact that the square wave circuit works and so does my Output stage.
I can't figure out Why I keep destroying Mosfets, the circuit should work.
Each of the 4017's fires in tandem, first IC1 then IC2. I've tested this with two LED's, one at each of the Diode Junctions and confirmed that they do indeed fire in tandem, not at the same time.
I know theres someone out there that can help me.
Any help would be Great!
Sincerely Aliman
I have attached two diagrams of the square wave circuit which drives a basic Mosfet Output stage. A very stable Square wave is generated by the 4069 Cmos Hex Inverter then fed to two pairs of High current Mosfets. This combination works Great!
I wanted to improve on the Inverter by adding a PWM circuit to achieve a Modified Sine Wave so I can run virtually anything on it. I have also added a schematic of a PWM circuit I found on the Internet. Its an ingenious design using Two cascaded 4017 Decade counters, achieving frequency division and a very nice wave form, also a diagram of that.
I first built the PWM circuit on a Breadboard and verified that it does produce the specified wave form.
Then I built the circuit onto a PCB. In doing so I basically put the PWM circuit just after the Output of PIN #2 of the 4069, grounded out PIN #3, then put the Buffer Transistors TR1 & TR2 , 10K & 1K Bias Resistors to the end of the Diode Junction Outputs.
I had to modify the Output of Square wave generator so that it produced a Frequency of 1.086 KHz ,this frequency is sent to the Two 4017's which have Ten Outputs each for a total of twenty, which act as Frequency Dividers. Theorecticaly a Input frequency of 1200 Hz would give you a final Output frequency of 60 Hz. For some reason in my actual circuit, I need an Input frequency of 1086 Hz to have a final Output frequency 60 Hz.
I have included a screen shot of the wave form captured on my Laptop Oscilloscope.
Now the BIG problem is that when I remove my Original Square wave generator and replace it with the New PWM Square wave circuit in place of it, when I turn the Inverter ON, it blows a Mosfet in the Output stage, and I have to quickly turn the Inverter OFF. This is what is confusing me. I know for a fact that the square wave circuit works and so does my Output stage.
I can't figure out Why I keep destroying Mosfets, the circuit should work.
Each of the 4017's fires in tandem, first IC1 then IC2. I've tested this with two LED's, one at each of the Diode Junctions and confirmed that they do indeed fire in tandem, not at the same time.
I know theres someone out there that can help me.
Any help would be Great!
Sincerely Aliman
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