The circuit represents a general-purpose astable multivibrator that alternatively energizes two heavy loads via a relay (in this case, the loads are 12-V incandescent lamps). In contrast to an ‘analogue’ flip-flop, here it is not necessary to use power transistors with heatsinks. This alternating blinker can thus be built at a lower cost, more easily[…]
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Simple Remote Control Tester Schematic Circuit Diagram
Nearly always when a remote control doesn’t work, the underlying problem is elementary: the unit does not emit light. The cause may be dry solder joints, defective LEDs etc., but also a flat battery (perhaps due to the stuck key). The human eye is unable to perceive infra-red light. By contrast, an ordinary phototransistor[…]
Read moreRotary Encoder for Digital Volume Control Schematic Circuit Diagram
The digital volume control published in Elektor Electronics October 1997 can be used either with an RC5 remote control or with two pushbuttons (louder/softer). If for whatever reason you cannot do without the feeling of turning a real potentiometer, then with a little effort it is possible to add a shaft encoder to provide rotational[…]
Read morePump Protector Schematic Circuit Diagram
This circuit has been developed to limit the running time of a sump pump since the pump can be damaged if it runs too long when the sump is dry. The circuit detects how long the pump has been switched on, and if this time exceeds a previously set limit (30 minutes in this case),[…]
Read moreFuse Failure Indicator Schematic Circuit Diagram
This circuit indicates when a device is functioning or when its fuse has blown. It is a development of the Mains/Fuse Failure Indicator published in Elektor Electronics July/August 1995. It is smaller and cheaper than the previous design, even though it works on any mains supply voltage. A single bi-color LED (D2) with separate anode[…]
Read moreSimple IR Receiver Schematic Circuit Diagram
This circuit has been designed to complement the ‘Simple IR Transmitter’ and to decode its transmitted signals. The similarity to the transmitter can be clearly seen: the received data is decoded by a shift register (74HC4094), which again is clocked by a counter/oscillator (74HC4060). The receiver is started by the first edge from the IR-receiver[…]
Read moreBALANCING LI-ION LI-POLYMER BATTERIES BATTERY BALANCING CIRCUIT Schematic Circuit Diagram
In addition to the ” Li-ion Battery Charge Integrators MCP73831 TP4056 “, ” Battery Protection Circuits “, “About Li-ion Li-Po LifePO4 Piller ” shared with Li-ion and Li-po batteries for charging, protection , balancing, balancing I will give you some information about … In general, many projects are carried out with a single battery. Serial battery connection is required for higher voltages. In this case, if[…]
Read moreSimple IR Transmitter Schematic Circuit Diagram
This circuit uses just two standard logic ICs which, with the accompanying receiver, forms a four-channel remote control and has been designed for use with the ‘Audio/Video Switch’ and the ‘Switchbox for Loudspeakers’ (shown elsewhere in this issue, as is the IR Receiver). Each pushbutton is connected to an input of a shift register[…]
Read moreZero-Crossing Detector for Microcontrollers Schematic Circuit Diagram
In lighting controllers and clock circuits that need the mains frequency as a parameter for evaluations carried out within a microcontroller, you will often find a transistor stage to convert the mains voltage (reduced by the transformer) into a 50-Hz square wave signal that is suitable for input to the microcontroller. Generally speaking, this[…]
Read moreTransistor Tester Schematic Circuit Diagram
This tester is intended to quickly check whether a transistor is functional or not and possibly also select two or more transistors with (approximately) equal gains. This is about the simplest conceivable test circuit, so don’t expect super accuracy. The circuit has been designed only to quickly carry out a brief check when there is[…]
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