In a computer having switch-mode power converter, a pulse transformer circuit drives the converter's transistor switch in response to pulses from a switch control pulse source. A primary capacitor is connected in series with the switch control pulse source and the transformer's primary winding. At the leading edge of a switch control pulse, the primary capacitor causes a positive voltage spike to appear across the primary winding and hence a positive voltage spike to be induced across the transformer's secondary winding. At the trailing edge of the switch control pulse, the primary capacitor causes a negative voltage spike to appear across the primary winding and hence a negative voltage spike to be induced across the transformer's secondary winding. The induced positive voltage spike causes a driver to activate the transistor switch and maintain the activation of the transistor switch until an induced negative voltage spike, and the induced negative voltage spike causes the driver to discharge the transistor switch.
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