The `crossed-flags` topology of a monostable multivibrator. Also, this particular board happened to be a 912 tach, so R5, which determines the discharge rate of C2,would be different for a 911. 912`s have a 50% duty cycle (four cylinders, 45 degrees of dwell or MARK time per ignition event- that`s 180 degrees total or 50% of 360 degrees of distributor rotation- another
Click here to download the full size of the above Circuit.
way to think about it is in 360 degrees of distributor rotation there are four ignition events or 90 degrees per event, of which the points are closed and distributor output is HIGH for 45 degrees or 50% of that) For a 911 you want a 63% MARK time, the points are closed 38 out of 60 degrees. With the car running +14V present on the voltage regulator circuit at the lower left. The Zener (value unknown at this point) has a breakdown voltage of a certain amount which limits the voltage on the top rail and the capacitor wired in parallel smooths out variations in voltage (ripple from the alternator that`s not damped out by the ship`s battery) Both the base of Q1 and Q2 are connected to the emitter of Q3 (I`m going to call this "ground" in the discussion below) through 2. 2K resistors but slight variances in the circuit mean one of them turns on first, it doesn`t matter. Suppose Q1 saturates first, its base is connected to ground through R5. Its collector gets pulled up above ground to positive voltage. This positive voltage is connected to the base of Q2, holding Q2 OFF. Next, a positive pulse arrives at the /1 terminal from the points. This goes through R8 and R6/R7 wired in parallel to the base of Q1, turning it OFF (thanks Loren for the clarification). Eventually C2 is fully charged and no more current flows, so the base of Q1 drops to ground through the 2. 2K resistor and C2 acts like a battery and discharges through the...
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: