Hi,
sometimes i need a power source to run a small single phase asynchonous motor at half speed . It's well known that such a power source should generate 25 Hz and 110V for a motor rated to 230V and 50 Hz. A lot of frequency converters available at the moment, but i do not need a dozens of various modes, functions and numerous menus... In addition, FC is a bulky and expensive device to be used with motor rated at 30 or 50W.
So, a circuit was found in the net:

http://www.frequencyinverter.org/frequency-converter-50hz-to-60hz-design-821996.html

A dozen of users posted their questions at the end of the article. Unfortunatelly, two of them reported the FC burned down... What's may be wrong with it? Transients at startup?
And one more question- what i need to do to generate more sinusoidal output? Asynchronous motors don't like "modified sine wave". Use another type of counter intead of 4029' ?
Thanks in advance

 

A dozen of users posted their questions at the end of the article. Unfortunatelly, two of them reported the FC burned down... What's may be wrong with it? Transients at startup?

There are various reasons, depending on which component 'burned down'. To name but a few: excessive load, highly inductive load, inadequate supply decoupling, under-specified capacitor ratings, inadequately-rated FETs, failed drive logic, .......

And one more question- what i need to do to generate more sinusoidal output?

Use a far more complex circuit, involving PWM, to generate a so-called 'pure sine-wave' inverter.

 

There are various reasons, depending on which component 'burned down'. To name but a few: excessive load, highly inductive load, inadequate supply decoupling, under-specified capacitor ratings, inadequately-rated FETs, failed drive logic, .......

There's no mistakes in the circuit diagram, you mean?

 

There's no mistakes in the circuit diagram, you mean?

That's not what I meant. But now you mention it, I see pins 12 and 13 of the CD4001 are floating. That's a mistake (although the write-up does say how it should be fixed).

 

That's not what I meant. But now you mention it, I see pins 12 and 13 of the CD4001 are floating. That's a mistake (although the write-up does say how it should be fixed).

Yes, i agree.
Anyway, those unused 4001" inputs can't affect the overall perfomance

 

Yes, i agree.
Anyway, those unused 4001" inputs can't affect the overall perfomance

Oh, but they can. An unused input on a 4000 series CMOS device can oscillate causing other devices in the package misbehave as well. This is the difference between engineering and hacking. You get what you pay for.

 

Oh, but they can. An unused input on a 4000 series CMOS device can oscillate causing other devices in the package misbehave as well. This is the difference between engineering and hacking. You get what you pay for.

From my practic- input of CMOS was left floating... The result was relatively huge current drawn by CMOS package- miliamps instead of microamps
No more essential mistakes , except of floating CMOS inputs ?

 

No more essential mistakes , except of floating CMOS inputs ?

No more obvious errors in the circuit shown; but that circuit is no use to you if your motor can't handle a 'modified sine-wave'.