Hi Gerard
On the sketch you just posted what is what looks like “600 it 3”??
Should “coppa” be “copper” or is it something different.
Cheers Bob
My bad writing. Copper and about 600Hz. The frequency is not that important…300Hz would be OK too.
Hi Gerard
300Hz would probably be better. If that coil has appreciable inductance 600Hz might not do much. You might even have to go lower than 300Hz.
Your armature might be better if it were soft iron as well. Will magnetise easier than steel. Like transformer laminations. Iron not steel.
Cheers Bob
Thanks Bob,
I was thinking more about this. Actually, the frequency can be really much lower. We’re trying to excite a tiny magnet to vibrate gently in a tiny volume of liquid.
I should find out the density of the liquid as this will affect how much energy we need.
Gerard
1 Like
Hi Gerard
This might require an AC signal exciting the magnetic field. The field will have the same polarity all the time with DC.
You will not get an AC signal from an Arduino. It is pulsating DC. That is zero to VCC. Never goes negative. You might need some sort of power amplification as I don’t think an Arduino can provide enough current. Depends in how much power you need.
If you need AC you CAN get it from Arduino by setting Arduino for a pulse signal at 50% duty cycle then passing this through a capacitor which will remove the DC component. Any subsequent amplifying after this process will require a split power supply (+ and - WRT zero V).
Unless you can find a good mathematician There is going to be a lot of experimenting involved.
Good luck.
Cheers Bob
EDIT
Instead of a split power supply it might be possible to drive the coil with a transformer secondary and leave out the capacitor. Would have to think about that
3 Likes
How about just using a small stepdown transformer with the on/off controlled by a triac switch. 50Hz (or 60)?
1 Like
Hi Gerard
What is the Arduino switching. Is it controlling the intensity of the magnetic field. If so what is it detecting to enable control.
I would see if such an arrangement will work first. It might be that the little magnet leaps out and attaches to the iron armature. The simplest way might be to raise and lower the whole coil/armature assembly above the container to get the result you need before you start with Arduino/Triac etc. See if this system is feasible first.
Methinks a fair bit of experimenting required yet.
Cheers Bob
I think you’re right here and it’s my own thinking as well. Sometimes you just have to do some experimenting. The Arduino is just a timer to turn the triac on/off. Nothing fancy.
The Uni is send me some vials so I can get a better understanding.
I was even thinking about winding my own coil and was reminded of the time when I was a teenager and radio enthusiasts would wind their own RF and IF coils. That’s going back a looong time!
Hi gerard
I think the easiest way would be to get hold of a cradle relay of the required voltage and hack it for the coil. That way you will get the number of turns of the right gauge wire for the voltage selected.
Cheers Bob
1 Like
I have a glass vial from Uni Queensland to test with!
We’re in the wrong game, these Neptis lab testing devices retail for US$150,000!
