Transformer with air core

[Borber]

The article says 20/25 turns for transformer. You made it with 150/180 turns windings.

 

[freedomtruth]

Did you measure it or just take other peoples claims for granted? How much is the coupling factor or the leakage inductance?

To check the parameters, the coil length and approximate winding thickness must be known too. From the picture, I would expect single layer coils.

I measured a previous version of it using an LCR meter.
About the coupling factor, I don't know. Like I said I'm a newbie.
Windings thickness is about 2 mm. 4 or 5 layers.

Do you have a link for the previous designs you are trying to reproduce?

**broken link removed**
http://easy-pcb.com/blog/rangkaian-propeller-clock-codevision-avr.html
**broken link removed** (**broken link removed**)

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The article says 20/25 turns for transformer. You made it with 150/180 turns windings.

Mine is more based on this one: http://www.arjan-swets.com/tekst_hobby_propklok_mech_E.html

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@BradtheRad @crutschow: Thanks.I'm gonna go do some testing.

 

[BradtheRad]

I have wondered if the electric power could come from a generator, created by placing magnets around the stationary part. The wire coils will be in the spinning cylinder.

Magnets and coils will need to be oriented properly in order to generate electricity. Doubtless you will need two or more coils, each with a series diode.

Of course there should be no ferro-magnetic substances nearby.

I don't know that the above idea can work. I have not seen it mentioned in propeller clock projects.

It might even be possible to spin a small motor to generate electricity. Lock down the shaft. Draw juice from the spinning body. You might be lucky to find one that runs 6V at 200 mA.

 

[freedomtruth]

I have wondered if the electric power could come from a generator

This was discussed in an AVRFreaks thread and I think they came to a conclusion that it's not practical.

 

[freedomtruth]

I couldn't get a result with crutschow's circuit. It's too complicated for my knowledge.
I mean I can't even get the first circuit to work while It's proved to work by others.

OK. can anyone suggest a full-bridge circuit? Do I need double power supply for that?

 

[FvM]

I couldn't get a result with crutschow's circuit. It's too complicated for my knowledge.
I mean I can't even get the first circuit to work while It's proved to work by others.

The circuit would need a bit of tuning. The original design is showing heavy cross-conduction in simulation. But the basic concept is good.

OK. can anyone suggest a full-bridge circuit? Do I need double power supply for that?

No.

 

[godfreyl]

Why don't you just use brushes? It would be a whole lot simpler than trying to get the transformer to work. Simple and stupid-proof.

 

[freedomtruth]

OK. can anyone suggest a full-bridge circuit? Do I need double power supply for that?

No.

Sorry. I don't mean to be annoying but what did I do wrong?
Do you suggest I forget about building this thing?

 

[FvM]

The "no" is answering to the double power supply question. I didn't intend the ambiguity.

A H-bridge will work with a single supply. The main difference to a half-bridge with capacitive output coupling as suggested by crutschow is the doubled output voltage. But if you don't manage to operate a half bridge (may be with a more sophisticated gate driver circuit), there isn't much hope for a full bridge.

 

[BradtheRad]

An H-bridge will look like this:



As before I don't know where to set the coupling coefficient. (I used 0.6 here)

Values are not critical.

The switching components need to get high enough bias, so they can carry sufficient current.

Adjust frequency to obtain maximum output.

As for those other people who report success with the loose-coupled flyback design, I wonder if they mention that they draw a lot of amperes from the power supply?

 

[freedomtruth]

Thanks guys.
Can I use mosfets in this circuit?
I'm going to drive the H-bridge using a PIC18F26K22 which gives PWM with full-bridge output plus dead-time.