Edison Dynamo 1879

[Klaus]

Hi guys,
today i did my first testrun with my edison dynamo. I had success but the output is not that what i expected. May i have to change the design of a few parts. Power output is 12 volts at 2500 rpm. At short circuit operation to ground i get 4 amps. The phosphor bronce brush of the commutator are to hard and damage it, but not to bad for this prototype!
Now i take a beer!!

Regards Klaus

[ame]http://www.youtube.com/watch?v=1W8H7YR_oI8[/ame]

 

[solarenergyadventures]

Hi Klaus!
That is a beautiful looking dynamo! So what did the armature come out of? By the way, I'm reaaaally not any sort of expert on such things, but I think your low output problem is due to your brushes being about 90 deg from where they should be. I've had lots of generators and dc motors apart, but I've never seen one with the brushes lined up with the gap in the field magnets. Usually they are lined up right in the middle of the magnets, ie 90 deg. from where you have them. Anyway, I hope that helps!
Cheers!
Chris

 

[Klaus]

Thanks Chris,
i know what you mean. May that depend to the distortion of the magnet field , normal steel used for the poles, clearance between the poles and the armature, radius of the hole in the field, distance between the poles and so on. I tried to turn the brush but i come to the end of the way. If you lok to a modern electric motor or generator the radius of the poles ar always bigger than the armature.
Yes there is work to do!!
Regards Klaus

PS: I take another beer!!

 

[Generatorgus]

Klaus, nicely done.
The fact that you built it and it works is all that matters.
Have another beer, you deserve it, in fact, I think I'll have one myself.
Did you make the rheostat?
GUS

 

[johanvanzanten]

Hi Klaus,

Congratulations with your fine looking dynamo. Perhaps you are not satisfied about the results but they are not bad at all. A few years ago I made a smaller one and had a lot of trouble to get it working. The following things may be of help: The position of the brushes on the commutator is critical. The air gap must be as small as possible ( 0.05 mm- 0.1 mm ). The field coils must be small and thik to minimise the magnetic resistance of the fild circuit but this spoils the Original apperence of the generator. I used copper/carbon brushes in mine but small strips of thin brass will do the job. Fosforbronze is to hard. Success with your further experiments.

Regards, Johan.

 

[Klaus]

Hello GUS,
yes i made the rheostat by my self. For template i used a old catalogue from Wilbis Berlin. This company sold beginning 19th century very fine done ic machine dynamos and so on.The insulation plate at the frame are made of slate from a old blackboard 2 mm thick. The resistor coils are missing then it´s complete.
Klaus

 

[rleete]

Very interesting model. Thanks for sharing.

 

[Klaus]

Hello Johan,
thank you very much for your congratulations, i will try your suggestions.You can see below i bought a couple old books about dynamos, some of them are more than hundred years old, they will help me. I already saw your fine done engine with dynamo at the model engineer photo gallery . Looks like the Liliput from Wilbis Berlin, i made this photos two years ago.
Also i saw your elegant Plank hot tube engine, respect.

Regards Klaus

 

[johanvanzanten]

Hi Klaus,

Thanks for the photo's of the Wilbis engine. I should have had such nice pictures when I was building my engine. When I made the dynamo I had the Wilbis in mind. It is only much smaller. The armature diameter is only 25 mm. It delivers 12 Volts and 1 Amp. The IC engine is the limiting factor. The field coils are energized via an electronic regulator to avoid flickering of the lights. The rheostat is an (electronic) voltage control.

Kind regards, Johan.

 

[Noitoen]

Are you connecting the field coils directly to the armature? If so, connect a little rheostat in series or wind some more turns with thinner wire. Thick gauge wire on the field coil is used in series with the armature for regulation purposes having a thin winding with a lot of turns to strengthen the field. You are now using all the "juice" to power the field coils.

 

[Klaus]

Hello Helder,
yes the field is connected directly to the armature in shunt circuit. My rheostat is not finished yet and i had no time to do detailed measurements. The field take 2 amps.
The amount of the magnet wire i took from a old book from the 1920´s "How to built a dynamo machine for 25 volts and 3 amps".

Regards Klaus

 

[Noitoen]

Hello Helder,
yes the field is connected directly to the armature in shunt circuit. My rheostat is not finished yet and i had no time to do detailed measurements. The field take 2 amps.
The amount of the magnet wire i took from a old book from the 1920´s "How to built a dynamo machine for 25 volts and 3 amps".

Regards Klaus

You can't use the same information for the field winding since your armature is not the one from the example. You should try different windings (turns and gauges). Only by experimentation will you find the correct combination. Remember, the strength of a magnetic circuit is a ampereXturn relation so, if you can get a winding of 100 turns to draw 2 amps, it will get the same strength as 200 turns with 1 amp but, you will get less loss of energy due to heat dissipation.