Every DIYer should have these three inexpensive electrical testing devices. They're handy even when you aren't doing ...

Figure 3 Two LED drivers operating in series or parallel let you boost zener voltage or current. Figure 4 shows an assembled zener-diode-tester circuit. The zener diode under test is On ...

The oscillator uses an inverted Wien-bridge topology with amplitude stabilization through an LED-driven CdS (cadmium-sulfide) photocell isolator. Using SPICE simulations before building the circuit ..