Electronics-Lab.com Community

# Capacitor circuit design...

## Recommended Posts

I am new here, so please forgive me and just tell me if I am in the wrong place for this.

It's been too many years since I've had to design a circuit in my head using capacitors.  lol  WAY too many years.

I am working on a project to pulse a magnetic field for a demonstration on electomagnetics.  I've got a coil... I've got a Pyramid 2.0 Farad, digital capacitor.  I need some help in how to charge and discharge this thing into the coil.  The outcome needs to generate a measurable magnetic field for the purpose of this demonstration.

Can anyone assist me with this?  I've been working in the thinktank end of a lab (loosly associated with LLNL) for almost 13 years.  This project is for my Nieces 10th grade class in school, where she asked me to speak on EMF and EMP.  Speaking on it isn't a problem... designing a circuit to demonstrate it is eluding me.  I've looked in my laptop, in my books and in all sorts of databases we've got and can't find a clue regarding what I know is such a basic circuit.

Bottom line, I want to charge the capacitor... and then (at my command) via a button or whatever, discharge it into the coil.  I could also use some formulae that will give me an idea of the amount of windings I'm going to need to not damage the capacitor.  These darn things are expensive... I like purchasing components on the Lab's money more than my own, but we didn't have a small capacitor laying around.

I'll check back soon, anyone with an answer can also email me at: [email protected]

Thanks,

Todd

##### Share on other sites

Wow.............. a 2F capacitor!!!!! It must have a VERY SMALL voltage rating (must be a hold-up cap of some kind). Keeping integration out of it, it all goes back to

E=L*di/dt  and  i=C*dv/dt

If the cap voltage is indeed low, the DC resistance of the coil will also have to be very low so it can draw LOT's of current to generate the flux field you want. The pulse would have to be relatively small as to not saturate the coil, and loose the field. If the the coil took the form of a air core solenoid, you could demonstrate the field strength by "launching" a projectile from it.

##### Share on other sites

I would forget the capacitor and find a solonoid coil, like used in a washing machine water control.  Get an iron rod from the local hardware store that will fit in the coil, an iron or brass washer that will also fit the rod.  When 110VAC is applied to the coil, the washer will be propelled up the rod.  If you still want to use a capacitor, get a 200 volt, 400 microfarad cap and charge it with a bridge rectifier on the 110 volt line.

##### Share on other sites

If you still want to use a capacitor, get a 200 volt, 400 microfarad cap and charge it with a bridge rectifier on the 110 volt line.

Too dangerous!
Go to a place where they print photos and ask for a disposable camera. Remove its flash-tube. Switch the coil across its capacitor after it has charged. It has a few hundred volts but isn't as dangerous.
##### Share on other sites

:)or look at the topic in the high voltage stuff section , topic high voltage photo flash capacitor charger, theres allso an ignition coil version there to and they even charge up non photo flash caps to , as for the emp stuff look through the forums here for mini emp box schematics or circuits , i posted the circuit there  which comes from the free information society site on the net

##### Share on other sites

To generate high flux, you need high current NOT high volts!!!!! I would think that this is an experiment where you want to keep the voltage as low as possible, but still be able to generate a high flux field!!!!!

## Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

×   Pasted as rich text.   Paste as plain text instead

Only 75 emoji are allowed.

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.