An awful thing happened a few weeks ago. I ran out of telephones to restore. All my payphone projects were finished. They were lined up on shelves doing what antique telephones do best - collect dust. I also wanted to write about a special project for the New Year. Something that would be out of the ordinary, creative, useful, and unique - and cou
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ld actually be used and enjoyed. 2- The input of the controller would plug into a standard subscriber line. The output would mimic the operation of a payphone line circa 1950`s, including the timing of all the functions. 4- It had to operate every prepay model made by Western, Northern or Automatic Electric. Regardless if it was two piece, handset, single coil relay, double coil relay, rotary or Touch Tone. 5- It would collect or return the initial deposit on hang-up, controlled by a timing circuit. Called party supervision no longer existed and getting involved with SIT and voice cadence recognition for a hobby project was out of the question. After six months of circuit design I ended up with a device that was expensive and complex to build. Fortunately at that time I had the facility around me to do the job. Unfortunately that facility and most of my vendors from that time no longer exist. 8- To meet the first three criteria a coin must be deposited in order to answer an incoming call. The coin will be treated like an initial deposit for an outgoing call when the phone is hung up. 12-The main purpose of this controller is to animate the payphone`s coin mechanism. Really making the phone into - A PAY PHONE! Due to the characteristics of the double coil coin relay used in early model payphones, it`s not possible to power them from the phone line. You can however replace the old style hopper and double coil relay with a...
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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