This design was created at the request of my father. It is designed to operate a 240V a. c. heater, in his Orchid box, to maintain a higher temperature during daylight hours than darkness. Regulator - This is a very simple regulator used here to obtain a stabilised 12V supply. The 78M12 regulator used is rated for 0. 5A, but any 78 12 regulator coul
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d be used if it provides sufficient current for your circuit. I had problems with the circuit due to ripple on the output, from the mains supply, and I fitted C4 to remove it. An option is to fit LED3 to indicate power with R9 acting as a current limiter. Light Level Sensor - An ORP12 (LDR1) light dependant resistor is connected to a very simple circuit to swap between day an night settings. The unit will trigger once the light level drops below a certain level set by VR1. When dark enough, TR1 will cause the relay (RLA1) to operate. Optionally LED1 can be fitted to indicator daylight mode with R6 acting as a current limiter. D2 is fitted to prevent the back EMF generated when RLA1 is switched off from destroying TR1. When the unit triggers, TR2 is energised and provides an additional voltage to TR1. This introduces hysteresis in to the unit and stops it switching back and fore if the light level fluctuates around the trip point. Thermostat - The basic principle of this unit is the same as my original thermostat designs. The main difference is that during darkness RLA1 will not be energised and therefore VR3 will be short circuited by the relay contacts. The resistance in the circuit during darkness will be R7 and VR2 and therefore between 91k and 113k, giving switching temperatures between 0 °C and 27 °C. When the light level rises causing RLA1 to operate the value of VR3 will be in series with R7 and VR2, giving an...
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.....
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