I've had to design and build an oscillator (which can have its frequency and amplitude altered) capable of driving an electromagnetic vibrating unit. I've created a square wave oscillator using a 741 IC, with an operating frequency from around 20 Hz through too 400 Hz. When hooked up to an oscilloscope the output is a nice and clear 5V ac (10V p-p) square wave. The problem arises when I feed this input to try and drive load, which is the electromagnetic vibrator. The data sheet specifies the vibrators resistance is 8 ohm. What I noticed is that the previously uniform 5V ac square wave collapses to nearly negligible values (500mV) and in turn isn't able to even begin to drive the unit.
I've tried using the signal to drive a npn transistor in saturation, so it is acting as a switch, however I don't think the 741 is outputting enough current (max 20mA) to drive the transistor into saturation. My plan was to use the output of the 741 to switch the transistor on and off, which will be directly shorting a 9v battery to the input terminals of the vibrator, as from tests completed a 9v battery provides enough power to drive the unit.
I've tried feeding the signal into a LM317 operating as a current regulator to try and increase the current, however the same problem still occurs when the output is used to drive the load, being the voltage collapses and distorts and I believe the frequency range shoots up into the kHz region.
Any idea's, thoughts our helpful hints would be very much appreciated.
I've tried using the signal to drive a npn transistor in saturation, so it is acting as a switch, however I don't think the 741 is outputting enough current (max 20mA) to drive the transistor into saturation. My plan was to use the output of the 741 to switch the transistor on and off, which will be directly shorting a 9v battery to the input terminals of the vibrator, as from tests completed a 9v battery provides enough power to drive the unit.
I've tried feeding the signal into a LM317 operating as a current regulator to try and increase the current, however the same problem still occurs when the output is used to drive the load, being the voltage collapses and distorts and I believe the frequency range shoots up into the kHz region.
Any idea's, thoughts our helpful hints would be very much appreciated.
