Hi I am experimenting with various design coils using different cross section conductors (not normal round wire) I need a driver. I have a signal generator that delivers up to 2 volts and a scope but I need to construct a device that I can drive using my sig gen that will deliver amps into the coils my coil resistance is as low as .3 ohms. I need some ideas of circuits etc.
Ian
Quote from: peth on October 03, 2009, 05:20:15 PM
Hi I am experimenting with various design coils using different cross section conductors (not normal round wire) I need a driver. I have a signal generator that delivers up to 2 volts and a scope but I need to construct a device that I can drive using my sig gen that will deliver amps into the coils my coil resistance is as low as .3 ohms. I need some ideas of circuits etc.
Ian
Hi Ian, I'm experimenting with similar circuits, all you need is a power mosfet attached to a heat sink. I don't know what power source you have? or what voltages you are using! A variable power supply is ideal. First you need to identify the connections of your mosfet. I use IRF740 only because I salvaged them from a scrap inverter. The device is known as a TO220 package with a mounting hole through it's heat transfer tab. This package is quite common. You have three connections... GATE, DRAIN and SOURCE. connect the SOURCE to ground / common negative of your supply. Connect the DRAIN to one end of your coil to be driven, the other end of your coil will connect to supply positive through a choke coil* Next you need a preset pott arround 1K ohm and a resistor of say 200 ohm. Connect the resistor to one end of the pott and the other end to the GATE of the mosfet. The wiper connection can connect to the output of you signal generator. This arrangement will give you the oppatunity to experiment with various gate bias settings. Connect your scope to the DRAIN and monitor your wave forms. If you use multiple windings connect your scope indirectly to the DRAIN as the pulse voltage developed will overload the Y amps in your scope if not attenuated. I suggested Mosfet's as they are easy to work with for this application. The IRF740 has an internal supression diode to compensate for back EMF's when switching inductive loads, there are many other similar devices you can use. Down load a PDF of your chosen device. Another good tip... loads of scrapped PC's arround, retrieve the power supplies for useful bits! Lastly a choke is just a single coil wound on a ferrite former a value of arround 100uH should be ok this goes between your coil and positive of your supply. Have fun Regards Merv.
Thanks, have other things to attend to just now but will go over and soak up what you have outlined ;D
Ian