quote:

---

Originally posted by JUAN DELA CRUZ
Regarding about the Xformer....If I'll make a 8v -0v- 8v primary winding(w/ 220V secondary) I'll turn the magnetic wire "8 times" in the iron core????

---

quote:

---

Do you have an short & overvoltage protection circuit that I can use w/ my Modified Sine Inverter to protect the Load...cause I'll using it to power a modified sine compatible COMPUTER.????

---

quote:

---

What will be the value of ZENER diode to Protect the Power mosfet from "Voltage Spike" when the Battery clip is suddenly disconnected????[/b]

---

quote:

---

Originally posted by audioguru

You found a very old under-voltage and over-voltage circuit. A simpler modern circuit is made with two opamps or comparators performing as a window comparator. Dennis recently posted the schematic for his window comparator.

What will cause the 12V input voltage of your inverter to be too high?

---

Thank you again Mr. audioguru,

The 12V input voltage of my modified sine inverter is O.K.

........but my problem lies at the output of the Xformer(secondary side).The voltage in the output of my inverter varies.
(due to battery voltage variation, i.e. approx. 13.8V when full & 9V
when nearly discharge).

....do you think a Zener diode can regulate the output before coming to the primary side of the Xformer????

...the down side will be less power output because less RMS voltage will go to the primary winding right...???

.......but the output will be more stable.


OR....do think an "automatic voltage control" w/ SCR will be the answer????

quote:

---

---

P.S...........Do you think this charger(Aaron designed) can lenghten the charge of the battery of my Modified sine inverter if I'll power it in the output of my inverter & then automatically charge the battery (i.e. disconnect when fully charge & then charge it again when the charge is low)??????
Download Attachment: charger2-1.gif
4.32 KB






Thank you.....

quote:

---

Originally posted by audioguru

You should not regulate the output voltage of your simple inverter by using a huge zener diode to short its input with about 700W of wasted power. The inverter circuit is too simple for voltage regulation. [quote]

---

Thank you Mr. Audioguru....

What should I do so that the output voltage of my modified sine inverter will be more stable.

...you said that using a Zener to regulate the output will wasted a lot of power.

...what if the output of the individual power mosfet is regulated so that the voltage coming to the primary winding of the xformer is stable likewise the output will be stable right???


Thank you.

quote:

---

Originally posted by JUAN DELA CRUZ

quote:

---

Originally posted by audioguru

You found a very old under-voltage and over-voltage circuit. A simpler modern circuit is made with two opamps or comparators performing as a window comparator. Dennis recently posted the schematic for his window comparator.

What will cause the 12V input voltage of your inverter to be too high?

---

Thank you again Mr. audioguru,

The 12V input voltage of my modified sine inverter is O.K.

........but my problem lies at the output of the Xformer(secondary side).The voltage in the output of my inverter varies.
(due to battery voltage variation, i.e. approx. 13.8V when full & 9V
when nearly discharge).

....do you think a Zener diode can regulate the output before coming to the primary side of the Xformer????

...the down side will be less power output because less RMS voltage will go to the primary winding right...???

.......but the output will be more stable.


OR....do think an "automatic voltage control" w/ SCR will be the answer????

quote:

---

---

P.S...........Do you think this charger(Aaron designed) can lenghten the charge of the battery of my Modified sine inverter if I'll power it in the output of my inverter & then automatically charge the battery (i.e. disconnect when fully charge & then charge it again when the charge is low)??????
Download Attachment: charger2-1.gif
4.32 KB






Thank you.....

---

quote:

---

Originally posted by audioguru

quote:

---

Originally posted by mrenjan

One Question to AudioGuru.. Is there any advantage of using 2N3055 instead of Mosfet's like IRF540 directly tied to CD 4047. We dont even need the OP-amps since Mosfet requires only less Drive current. Probably the only other change required is in the Transformer side (9-0-9 instead of 12-0-12). I thought the efficiancy of Mosfet is much higher than Transistor since leakage current is less. Not sure whether i am wrong.

---

2N3055 transistors were used in the 100W and 500W inverter because the circuit is very old and 2N3055 transistors atre available in countries that don't have Mosfets. Mosfets are much better.

The IRF540 Mosfet is also getting pretty old since much better Mosfets are available now.

The CD4047 can directly drive two Mosfets in an inverter and the output power depends on their current rating and the size of the heatsink. Cheap Chinese inverters use Mosfets.

Efficiency is determined by how much power is wasted as heat in the transistors when they conduct, not leakage current.
A 2N3055 transistor has a max saturation voltage of 3V at a collector current of 10A and a huge base current of 3.3A. That is 35W of heat for a 100W inverter.
An IRF540 Mosfet has a max saturation voltage of 0.44V at 10A so wastes only 4.4W in a 100W inverter. Better Mosfets would operate cooler and therefore the efficiency would be higher.

If you use a 9-0-9 transformer with Mosfets then with a fully charged battery at 13.8v the output voltage will be 170VAC instead of 115VAC or will be 341VAC instead of 230VAC.

If you use a 12-0-12 transformer with Mosfets and a fully charged battery then the output will be 128VAC instead of 115VAC and will be 256VAC instead of 230VAC.

---

quote:

---

Originally posted by audioguru

quote:

---

Originally posted by mrenjan

One Question to AudioGuru.. Is there any advantage of using 2N3055 instead of Mosfet's like IRF540 directly tied to CD 4047. We dont even need the OP-amps since Mosfet requires only less Drive current. Probably the only other change required is in the Transformer side (9-0-9 instead of 12-0-12). I thought the efficiancy of Mosfet is much higher than Transistor since leakage current is less. Not sure whether i am wrong.

---

2N3055 transistors were used in the 100W and 500W inverter because the circuit is very old and 2N3055 transistors atre available in countries that don't have Mosfets. Mosfets are much better.

The IRF540 Mosfet is also getting pretty old since much better Mosfets are available now.

The CD4047 can directly drive two Mosfets in an inverter and the output power depends on their current rating and the size of the heatsink. Cheap Chinese inverters use Mosfets.

Efficiency is determined by how much power is wasted as heat in the transistors when they conduct, not leakage current.
A 2N3055 transistor has a max saturation voltage of 3V at a collector current of 10A and a huge base current of 3.3A. That is 35W of heat for a 100W inverter.
An IRF540 Mosfet has a max saturation voltage of 0.44V at 10A so wastes only 4.4W in a 100W inverter. Better Mosfets would operate cooler and therefore the efficiency would be higher.

If you use a 9-0-9 transformer with Mosfets then with a fully charged battery at 13.8v the output voltage will be 170VAC instead of 115VAC or will be 341VAC instead of 230VAC.

If you use a 12-0-12 transformer with Mosfets and a fully charged battery then the output will be 128VAC instead of 115VAC and will be 256VAC instead of 230VAC.

---