- This topic has 1 reply, 2 voices, and was last updated 3 years, 5 months ago by Michael.
2020-April-05 at 11:19 #8553LectronFanModerator
I received a motor block !
Time to grab our Lectron modules and do some experiments with it !
First some info about the motor :
It has 2 connections : a DC and an AC connection. Both share the same coil but the rotating contactor has separate contacts.
The side magnets (North and South) are housed in separate cubes.
In rest, the rotor is so constructed that the DC contacts are open. This has the advantage that the very low DC resistance of the rotor will not destruct the driver circuit (due to very high current).
The disadvantage is that we have to “start” the motor by gently turning its shaft.
Another option is to set the rotor so that it is balanced between the 2 North and South pole magnets.
Time for an experiment !
We can not use the NPN or PNP transistors of our Lectron set. The motor (when turning) consumes about 180 mA which is too high.
Luckily, We also have MOSFET transistors, the IRFZ24N (N-channel Mosfet) with order code 2443 and a IRF9Z24N (P-channel Mosfet) with order code 2444.
They both can handle 12A.
Before handling the Mosfet module, touch the metal ground plate to discharge yourself from static electricity.
Let’s make an experiment to demonstrate the motor with Mosfet transistor driver. We will also add a darlington amplifier to drive the Mosfet.
When finished assembling the circuit, set the motor at a 6 ‘o clock position (the rotor will be in the middle of the 2 magnets, so it will rotate from itself).
Touch points A and B together; The motor starts spinning at a high speed.
But wait, there’s more to experiment !
Set the motor back in the 6 ‘o clock position.
Now, only touch point B, do you notice that the rotor swings to its rest position ?
If this was not happening, touch only point A several times. With the same finger touch point B now, you saw the motor moving ? True magic !
The secret is that tiny amounts of static electricity will be strongly amplified in our Darlington transistors and the very sensitive Gate of the Mosfet reacts to this. Since we have put the rotor between the 2 magnets, only a tiny current through the motor coil will induce a small magnetic field. This is just enough to unbalance the rotor.
Remember to keep the motor running for a short time to save the motor itself and the battery.
2020-April-06 at 19:02 #8557MichaelKeymaster
From where did you get the motor block? Is Martin ‘back in business’ or did this come from our mutual Lectroneer friend?
Perhaps you might post a picture in your above post as this is certainly a somewhat rare block.
Thanks so much for your experiment analysis!
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