This circuit demonstrates a simple universal voltage doubler using the popular timer IC NE555 timer IC. The timer is configured in astable mode to generate a switching signal of about 3kHz. This signal drives a complementary transistor pair consisting of BD139 NPN transistor and BD140 PNP transistor, which alternately switch the charge-pump stage. The voltage … Continue reading LIVE DIY: 6V, 9V and 12V Universal Voltage Doubler