The transistors do not necessarily have to be BC547B, you may use BC238 or similar small-signal transistors. It is recommended to always use the equivalent transistors. If one of the transistors is ...

This is a very simple LED dimmer circuit which has 2 transistors, 1 resistor and 2 potentiometers. Typical segment displays LEDs consume around 25 mA for each segment and should be limited to this ...

Seen in the accompanying schematic, the 555 square wave generator drives an MPF102 FET, which in turn drives a D718 power transistor that provides a “pulsed” 12V variable duty cycle driving the LED ...

What I came up with, is the circuit above. The idea is that the constant current source – a traditional two transistor source – feeds a few mA into the capacitor all the time – so no front lamp ...

But with our simple transistor circuit, 20 mA will always flow. Well. Sort of. ... There’s no point in precisely modeling the forward voltage of an LED or the current gain of a transistor.

This voltage-booster circuit for driving one or more white LEDs uses a 555 timer as its main element (see the figure). The timer, IC1, functions as a resettable astable multivibrator ...

The Fig. 1 example includes LED loads D1 + D2, D3 + D4, D5 + D6 and a power-supply output voltage, with a constant output current, providing the circuit input voltage (V IN).

A transistor and a few passives allow a SPST switch to act as an on/off switch: ... 21 thoughts on “ LED Driver Circuit For Safety Hat Sucks Single AAA Cell Dry ” Dan says: ...