Making an Adjustable Electromagnet

This article describes a simple circuit which can be used for pulsing an electromagnet. The IC 555 once again becomes the central part of the circuit. Let's learn the making procedure of this simple adjustable electromagnet circuit for varying the magnetic power of an electromagnet.


The circuit was requested by Mr.Jason, one of the followers of this blog. Though I'm not sure of the application needs, the circuit probably can be used for controlling the average magnetic power of an electromagnet or rather the circuit may be considered an adjustable electromagnet circuit.

The circuit involved is quite basic and has been already employed in many applications, explained in my earlier posts. Here the application is quite similar to the earlier ones, that is controlling the output load through a series of varying pulses or through PWM method.

Simulation and Working

The mark/space ratio can be appropriately adjusted using the shown configuration, which in turn can be used for varying the response of the output load.

Here the output load is an ordinary homemade electromagnet, connected via a power transistor TIP 122.

The power of the electromagnet is at the maximum level when the pot is set for achieving high mark levels than the space levels and vice versa for reducing the magnetic effects of the electromagnet.

The electromagnet may be procured ready made or can be hand made at home using suitable lengths of enameled cooper wire wound over a magnetic core, like an iron nail or rod etc.

The diode connected across the electromagnet protects the transistor from back emf fluxes of the electromagnet.

The circuit may be powered with voltages between 5 and 12, but the current must be appropriately rated, otherwise the circuit will fail to operate.... if a battery is used, make sure it's rated at least at around 1 AH.

Once powered, this adjustable electromagnet circuit will enable  smooth adjustments of the attached electromagnet's magnetic field from zero to maximum.

Circuit Diagram

Need Help? Please send your queries through Comments for quick replies! And please Bookmark my site :)


Hi! I was about to make something like this, since i need to test the speed sensor of my motorcycle (or modify the mileage, since i've buyed a new gauge that start from 0KM) but in a fast way (using high hz/Khz in the output of 555). So pulsed needed to simulate the wheel spining. This will work right? Thanks!
Swagatam said…
Yes, it will work in that way as it would effectively simulate the pulses acquired from a rotating wheel.
Rspene smit said…
What do you make the EM out of that would work best, wrap the red copper on an Iron Nail or sometype of Ferrite piece and if so, exactly what would i look for to purchased for it, thanks.
Swagatam said…
you can use an iron bolt and wind some 200 turns of 0.5mm magnet wire....but with an iron as the core make sure to reduce and fix the frequency of the IC 555 anywhere between 50 and 500 Hz not above this
TTGB said…
Could an LED display be added to this to visibly display the intensity of the magnetic field as it changes?
Swagatam said…
you can add an LED in series with the transistor base, this will enable the required indications...
Brett Buckley said…
Making a micro controller based project and my project is a crane that will also have an electromagnet for picking up objects, would this circuit work for that?
Swagatam said…
the 555 section might not be required for your application, just feed the MCU output to the transistor base for controlling the EM.
Aqib Ahanger said…
swagatam sir.... i have a 3 cable setop boxes... one has got a signal dropping problem which autimatically shows no signal after two or tgree minutes i have to switch on n off the supply of it then it worrks again n vice versa... another one shows on indicator but diesnt gives video out put at oll.. or like it doesnt takes the signal out put. .
Aqib Noor
Electronic n Electrical Technician...
Swagatam said…
I am sorry Aqib, i have no idea regarding signal processor units because these normally work with extremely sophisticated and complex circuits..

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