Australia's Science Forum

Hi Guys
Does anyone know a good brand/supplier of dynamos
Thanks

On the subject of dynamos, the rubber belts have busted over the holidays. I guess the heat affects where they are joined. Does anyone know where you can get decent belts from. The last one came from Serrata but has not lasted and didn't work very well anyway.

Try Science Supply's Sarrata get there's from China and they don't last.

Hello!
Does anyone have any ideas on how to fix this dynamo?

We've checked the LED's and the bulb, they work, and the connections from the contacts work. So no issue with the wiring from there.
We're thinking it's maybe the magnet or copper in there?

Thanks!

It's unlikely the Magnets have lost enough strength for it not to work to some capacity.
it is possible that the coil has gone open curcuit . You should be able to test the coil with a multimeter . It will probably read around 1-2 Ohms .

Is it easy to turn the handle ? If there is a short curcuit on the output somewhere , it will load the generator making it feel "hard" to turn .It may read closer to 0 Ohms on a Multimeter .

It sure does look like it is just an AC Dynamo or can you move the contacts so it generates DC as Well ?
If so , then you can test the thing by applying DC from a power pack at round 4-6V .
You will need to spin the motor to start it then it will keep spinning if the coil and magnets are good. LOL I even got our antique one to run this way even though it has really weak magnets ,( had to drop the belt though) Curious where you bought that from .Haven't seen that one before .
Can you show some close ups of the Commutator /Brushes

Not sure when or where it was bought.
Both contacts are touching, the image doesn't show very well

First pic: back
2nd: top
3rd: front

Thanks Emma .
I'm guessing from the Pics that you can move the contacts ,IE you can slacken the Green and Red knobs and slid the contacts along the rails to set it up for either AC or DC generation .
You might want to check the alignment or try the other position .
Hope this helps

Thanks, yeah we've tried that. Both ways it doesn't work, and I forgot to mention the wheel does spin easily, so not sure what the problem is yet.
thanks for your help though!

Sounds like the coil is open circuit . Have you checked for continuity through it ?....Either with a Multimeter on Ohms range ....or even a simple light bulb and power pack .

If the coil is open circuit , its more common that it will fail where the connections are soldered onto the commutator than an internal O/C in the windings .....so there is a good chance you can fish the wires out and reattach them , although if they are broken near the solder joint , they may no longer be long enough .No big deal , you can just lengthen them .

The help is no problem . I spent 30 years as a TV technician before being a Labbie so I done my fair share of fault finding electronic stuff .