# How to get inductor on 12v DC to output back EMF of 100v ?

#### russwr

Joined Aug 29, 2017
66
Need the hook up means to get 1.5 Millihenry coil to output 100 volts from 12v car battery? Back EMF. E = L X dI / Dt The shut off speed has to be fast. Charging inductor current .5-1 Amp DC. This is very fast, so I have small neon bub for 92v.

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#### MisterBill2

Joined Jan 23, 2018
19,040
You are attempting a BOOST type of switcher supply and that level of boost is difficult, at best. Then, we are given no hint as to the current required or the application.
And the reality is that the design of a switch-mode booster power supply is by no means simple, because every component and every conductor are critical circuit elements.

#### Papabravo

Joined Feb 24, 2006
21,264
Need the hook up means to get 1.5 Millihenry coil to output 100 volts from 12v car battery? Back EMF. E = L X dI / Dt The shut off speed has to be fast. Charging inductor current .5-1 Amp DC. This is very fast, so I have small neon bub for 92v.
Are you familiar with the immutable rule of DC-DC power conversion schemes? It seems that this precept may have escaped your notice.

#### crutschow

Joined Mar 14, 2008
34,697
Need the hook up means to get 1.5 Millihenry coil to output 100 volts from 12v car battery? Back EMF. E = L X dI / Dt The shut off speed has to be fast. Charging inductor current .5-1 Amp DC. This is very fast, so I have small neon bub for 92v.
Look at how a Kettering ignition system works.
Such a system can generate a several hundred volt pulse at the primary, when the primary circuit is suddenly opened.

Just substitute your inductor for the ignition coil primary.

A transistor switch is substituted for the points in modern versions of the system.

#### BobTPH

Joined Jun 5, 2013
9,174
I would actually be very surprised if you could not flash a neon bulb by putting 1 amp through a 1.5mH inductor, then turning it off. Show us the circuit you are using.

#### MisterBill2

Joined Jan 23, 2018
19,040
It IS possible to flash an NE-2 bulb across an inductor just by momentarily connecting a battery across the inductor and then disconnecting it. That inductor was much larger, a small power supply filter choke. probably closer to one Henry inductance.
But outside of a "boost" switcher supply the power delivered is not very useful.