Generate more force from a solenoid

Hello all,

I'm new to this forum and just getting started with DIY electronics and am hoping I could ask some advice. Please bear with me if this is really basic stuff, I am learning as I go!

So far I have managed to get a nice little prototype going that converts midi information to a solenoid output via an arduino leonardo and a transistor using a little 12V battery pack. I am using it for a musical percussion project, where midi notes will trigger a push/pull solenoid to fire and produce a 'hit'.

Fortunately, there are many similar projects out there on the internet to learn from, however I am having one issue that I am struggling to understand and resolve: how can I (if possible) generate more push force out of the solenoids I am using (below). For example, I was hoping to generate enough push force for the solenoid to depress a piano key and play a note, however with the 6V 5N solenoid I am using, I can't seem to generate enough force to depress the key. Is it an issue of power? Or do I need stronger solenoids?

Solenoid: Hechen solenoid electromagnet HS-0530B DC 6V 1A 5N 10mm stroke

Hechen solenoid electromagnet HS-0530B DC 6V 1A 5N 10mm stroke push pull type open frame: Amazon.co.uk: Business, Industry & Science

Hechen solenoid electromagnet HS-0530B DC 6V 1A 5N 10mm stroke push pull type open frame: Amazon.co.uk: Business, Industry & Science

www.amazon.co.uk

Thanks for your time.

That appears to only be returned to it's extended position by a (very) weak looking spring. Changing it to pull the key down should increase the strength. Alternatively, use a higher voltage and reduce the time active so it doesn't overheat (will still need to pull to get greater power). Try holding it in/out as you power it to see the difference. If you double the voltage then the on time can only be 25%. Note, you need to be careful that the processor doesn't crash (use WDT) as it may crash while the solenoid is activated and it may burn out.

Mike.

Double or Quadruple the voltage into a large cap, then switch a MOSFET to dump the CAP.

I have a current project at work where we are doing just that for a Client. The power supply is 12V and we are Quadrupling it before dumping it into a 12V solenoid for about 6mS.

Be sure and place a back emf diode across the Solenoid !!!

Beau Schwabe said:

I have a current project at work where we are doing just that for a Client. The power supply is 12V and we are Quadrupling it before dumping it into a 12V solenoid for about 6mS.

Click to expand...

Can you confirm that it was using the pullin power of the solenoid and not just the weak spring return? I nearly mentioned dumping a cap into it but thought it a little complex for a beginner. As (s)he's using an Arduino then timing shouldn't be a problem.

BTW, to the OP, are you driving the MOSFET direct from the Leonardo or via a MOSFET driver chip? You don't state which MOSFET you use. The Leonardo should drive a logic level MOSFET (IRL540 etc.) ok. Actually, a 2N7000 driving the solenoid on a 12V supply will probably do it.

Mike.

Hello both,

Apologies for a delayed reply - I've been working on a few other things.

First I will try pulling with the solenoid and see how strong it is.
Will then try increasing the voltage. As I mentioned, currently I am using a little 12V battery pack. What would you suggest is the type of power supply that would be a good next step up? As I said, learning as I go and so of course want to make sure I am progressing with safety in mind.

I am driving the IRF520 MOSFET directly from the Leonardo.

Really appreciate the assistance!

Pommie said:

Can you confirm that it was using the pullin power of the solenoid and not just the weak spring return? I nearly mentioned dumping a cap into it but thought it a little complex for a beginner. As (s)he's using an Arduino then timing shouldn't be a problem.

Click to expand...

Yes, it was the pull in power from the solenoid ... and yes, this may be too complex for a beginner. One thing to watch out for with an Arduino, it can "hicup" every now and then if you have other tasks in the background. We are actually using an Arduino with a BT Phone App to control the "Rate" and the "Strength" of the pulse.

echovoid said:

As I mentioned, currently I am using a little 12V battery pack. What would you suggest is the type of power supply that would be a good next step up?

Click to expand...

We are using a 12V pack as well, however we are also using a (4X) voltage multiplier, so the Solenoid sees close to 48 Volts for about 6mS every 1/2 second to every 2 seconds.

The type of multiplier we are using is called a "Dickson Charge Pump" with 3 stages ... using two half bridge MOSFET driver stages for the two 180 Deg clock inputs.

Reference:
https://en.wikipedia.org/wiki/Voltage_multiplier (See Dickson Charge Pump)

echovoid said:

I am driving the IRF520 MOSFET directly from the Leonardo.

Click to expand...

The IRF520 is not a so-called 'logic-level FET', so may not switch on fully when driven directly by the Arduino. That could be restricting the solenoid current. According to its datasheet a 'typical' IRF520 needs at least 4.5V on the gate to give a drain current of 1A. The threshold gate voltage can be as high as 4V just to get 250uA of drain current.