Photovoltaic switch disables unused LEDs


Posted on Mar 20, 2013

In many applications, it`s desirable to disable LEDs used for system verification. Many options are available for the disabling function, including manual SPST (single-pole single-throw) switches, enhancement- and depletion-mode MOSFETs, bipolar-junction transistors, and JFETs. The circuit in Figure 1 automatically disables the LEDs when a mechanical housing encloses the circuit card, thereby preventing you from accidentally leaving the LEDs on to waste power.



The main switch portion of the circuit comprises an amplified photovoltaic cell (photodiode) and a small, n-channel MOSFET. The amplified photodiode signal provides drive to the MOSFET`s gate when enough light is available. Because the photodiode gen




Leave Comment

characters left:

New Circuits

.

 


Popular Circuits

TDA1524 Stereo Tone Control
Voltage regulator for projection lamp
(N + 1) Wires Connect N Hall-Effect Switches
Triac circuit
speedcontroller Dead time effects Of IGBTs
build varying brightness ac lamp circuit
square wave oscillator circuit
Two channel audio mixer circuit design electronic project
MAX641 high current step-up converter
2003 gmc savana instrument cluster illumination lights
Automatic Headlight Reminder
circuit to test servo motor (pole rotor) of parabolic antenna
Discrete components sound and light control stairs delay switch circuit 5



Top