In the circuit of Figure 1, assume that a brush-type dc motor must drive a load back and forth between two endpoints on a lead screw. Optical sensors determine end of travel, and an SPDT switch selects to which end to send the load. The sensors ...
Over the years, various power-off circuits have been published. However, the circuit proposed here is very simple and has excellent characteristics. It features a fast power-off transition, with only 8 mV voltage drop at power on and sub-µA ...
Many applications that use 110 V/230 V-ac mains require a ZCD (zero-crossing-detection) circuit for the ac-line voltage, for example, to synchronize the switching of loads. One method of ZCD uses a high-value current-limiting resistor or a ...
A popular category of aiming/pointing aids is the reflex, or “red-dot,” sight. This system finds use in such diverse applications as astronomy, archery, and shooting. In the reflex sight, light from an internal source typically a ...
You sometimes need to drive a white LED from one 1.5 V battery. Unfortunately, the forward voltage of a white LED is 3 to 4 V. So, you would need a dc/dc converter to drive the LED from one battery. Using the simple circuit in Figure 1, you can ...
This Design Idea describes a single white-LED torch, which can be housed in an empty glue-stick tube and has a long rechargeable-battery life. The circuit is constructed with just a few commonly available parts. This torch has proven to be highly ...
TA Babu EDN LED technology is opening the door to a variety of high-power-illumination applications. The circuit in Figure 1 can let you know when ac power is available. To drive a power LED from the ac line requires a converter or a similar ...
Robert Most EDN Circuits that latch one-of-N switches usually use a digital approach. Such circuits are often useful in human-interface situations, such as audio-mixing consoles, video-feed selection, or current-loop-control redundancy systems. In ...
The circuit in Figure 1 is a good choice if you need a power supply with high efficiency and you don't want to use expensive dc/dc-converter ICs. The heart of the circuit is IC 1 , the common, inexpensive LM7805 linear regulator. The external ...
A microcontroller requires dc operating power in the 2 to 5.5 V range, an amount that a battery or a secondary power source can easily supply. However, in certain situations, a microcontroller-based product must operate directly from a 120 or 220 ...