This circuit shows how a 4017 CMOS decade counter can be used to build a timer circuit. Push-button S1 will discharge capacitor C1 through resistor R2. When S1 is released, C1 will charge up through R1 causing a rising edge at the clock input of IC1. This causes the output Q1 to go high (to the supply voltage). Current will‚ow through R4 and LE
Click here to download the full size of the above Circuit.
D D2 will light. At the same time C2 will begin charging through preset P1 and R6. When the voltage on C2 reaches approximately half the supply voltage it will reset IC1. Q1 will go low, the LED will go off and C2 will discharge through D1 and R3. The circuit will now remain stable in this reset condition until S1 is pressed again. Preset P1 allows the ON time of the circuit to be adjusted between 5 seconds and 7 minutes. The current consumption of this circuit in its reset state is only a few micro-amps, rising to approximately 8mA mainly due to the LED current, when S1 is pressed. When power is applied to the circuit IC1, can be in an indeterminate state and the LED may be on. Pressing S1 until the LED goes off clears this condition. Alternatively C2 may be connected to the supply rail (as shown dotted in the diagram) this will ensure that IC1 will always power up in a reset state. A disadvantage of this conguration is that any noise on the supply rail will be coupled through to the reset pin of IC1 and may affect the timing period.
This project fits more for custom made battery casing that can have more space to hide things inside. This switch with few alterations can be used for any other project as well but is designed based on e-bike needs! This project use a clever functionality of....
The circuit described here uses ultrasonic oscillations and operates based on the propagation velocity of these oscillations in the air. Thus, we can easily determine the distance of two points if the time within which the wave travels this distance is....
Sometimes the precious metals are hidden too deep and are not detected except with complicated devices. In many cases, however, small pieces of precious metal buried near the surface can be detected by relatively simple means. Everyone is very attractive to....
Many times for various reasons we forget or can not water the plants that we have in our homes. And many humidity sensors units just notify us with a beeping sound or with a flashing light, that the pot needs watering. But what if we are away from home? This....
The principle behind a metal detector is really very simple. Proof of this is the circuit that follows, in which it proves that the construction of a metal detector can be done in the minute, with few components that we find very easily everywhere. With the....
The sub-harmonic bass generator is a sound producing unit for guitars. The sound it produces looks very much like that of the bass guitar. The octave generator is sometimes quite unusual since it does not produce any of the usual ways of coloring the sound,....
In the past the sounding (sea bottom measurement) was done with the "bullet", that is, with a heavy lead object that the seamen plucked into the sea hung from a calibrated rope. As soon as the "bullet" reached the bottom, the depth appeared directly from the....
This Amplifier was designed to have the following specifications: Distortion less than 0.1% at full power of 100W even at 20KHz. Power has to be attributed to an extended bandwidth. The output transistors must be protected against short circuits. The power....
A series of LEDs serve to alert the gardener when plants need water. Using two conventional digital integrated LEDs and a series of LEDs, we make a very useful device for gardening. The device detects the amount of water in the pot and alerts the grower.....
characters left: