That means the inputs to an opamp is not necessarily can allow a voltage as high as Vcc. Some opamps allow that but the LM358 don't.One comment that L.Chung pointed is, Vcc common -1.5v. Need clarity liittle bit more what this means,
That means the inputs to an opamp is not necessarily can allow a voltage as high as Vcc. Some opamps allow that but the LM358 don't.
It is the same for 0V as well. The LM358 allows 0V while other opamps don't.
Exceeding that limit the opamp either don't work, work incorrectly or even suffer damage.
It all in the datasheet.
The outputs of the CD4047 switch at exactly the same time. There is no dead time to allow one Mosfet to turn off before the other Mosfet turns on. So there are moments when both Mosfets are turned on and then they short the supply.
An extremely simple square-wave inverter will not power many electronic products properly and has very poor voltage regulation.
The circuit is not properly designed and will not work satisfactorily:
1. CD4047 is used as a astable, its Q and /Q changes simultaneously and as other users have pointed out, there is no dead time for two drive legs of the inverter transformer. There is no way to make the chip output a dead time.
2. LM358 is an opamp and not a comparator. You are using it as a voltage follower but has exceeded its allowable common mode input voltage range of Vcc-1.5 maximum. This is not good. Why it is needed in the first place is questionable.
3. The gate drive to each MOSFET is effectively through 2.4K+82Ω so the gate charge current is very limited. The MOSFET turns ON slowly.
4. I have no idea of how the existing snubber works as it just charges up the 100uF when the leg is not conducting but discharge all its charge through the 0.5Ω into the MOSFETs to 0V, wasting energy.
The inverter circuit from Electronics-Lab was messed up (not corrected) by MP:
1) The current in each 2N3055 output transistor is 25A when the load is 500W. But the absolute max allowed current in a 2N3055 transistor is 15A and they perform poorly at more than 10A. My version (that MP deleted) used twice as many output transistors.
2) The output transistors must have their gain and base-emitter voltages matched. My version used 0.1 ohm series emitter resistors to help make the transistors the same.
3) The output and driver transistors do not have a resistor to turn them off and spike protection diodes are missing. My version had the resistors and protection diodes.
4) The CD4047 oscillator has an electrolytic capacitor with a value way too high and a timing resistor with a value way too low. My version used an accurate film capacitor and a much higher value resistor as recommended in the datasheet of the CD4047.
5) Two LM324 quad opamps are used. My version used a single LM358 dual opamp.
6) A very important fuse is missing in the wire from the battery. My version had a 60A fuse and on-off switch.
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