The project started with a request from a fellow member of the Long Eaton Club, Tony Bowler. He was interested in converting one of the `Golden Oldies` to electric free-flight. He choose Vic Smeed`s `Debutante` to power with seven AE size cells and a Speed-400 motor, but realized he required some sort of timer to give a predetermined motor run, an
Click here to download the full size of the above Circuit.
d asked if I could help. The design I came up with seems to fit the bill. It will switch up to 12 amps, has an optional soft-start for gear box applications, is simple to construct and all the bits are readily available from Maplins for under $10. The `ON` time is adjustable from 20 to 80 seconds, but other variations of the running time can be achieved. The heart of the circuit is the popular CMOS Timer IC, 7555. When power is applied from the battery, the IC`s output pin 3 is switched `OFF` (0V) and a short circuit applied to C5, thus ensuring it is completely discharged. When a momentary start signal is applied to pin 2, the output immediately switches `ON` (+V), thus switching on the MOSFETs and the motor via the soft start circuit R4, D1 and C6 (if fitted). This latter circuit slows down the switching on of the MOSFETs, giving a more gradual increase in current to the motor. If soft start is not required, omit these components and wire pin 3 directly to the MOSFET gate terminals G. When the voltage across C5 reaches 2/3V, the IC detects this and its output switches `OFF`, thus immediately switching the MOSFETs and the motor off via D1. The 7555 timer IC also re-applies the short across C5 and the circuit returns to its initial condition ready for the next motor run. Zener diode D2 provides protection to the MOSFETs from the high frequency transients that all DC motors generate, but do not omit the normal spark...
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: