This is a deeper look into the Port-O-Rotary phone. We stuck the GM862 cellular module into an old rotary phone enclosure, and voila, it was an instant, ridiculous, hit. Really simple - the GM862 requires 3. 8V and a Lithium Polymer outputs 3. 7-4V. No regulator needed, but we will need a charger. We currently use an external charger from a third pa
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rty company. Aubrey noted the GM862 has a built in Lithium-Ion charger that may work, we haven`t tested it yet. Ideally we would stick a barrel jack in the back of the enclosure where the RJ11 telephone jack used to reside. Anyone have any recommendations I have used the charging circuit in the GSM862 on the exact LIPO batteries you use and it works good, it takes forever to charge. NOTE: You must connect a low esr cap to the battery if you are using the internal charger. We use a 100uF 6. 3v cap in our design, Digikey part# 493-2309-1-ND. We use a PIC 16LF88 (remember we are at 3. 7V! We need a low-voltage PIC!) to read the hook and rotary. Pretty simple switch decoding routine. We just read the opening/closing of the paddles behind the rotary. There are two - one set of paddles opens and closes for each number that passes by, the other set of paddles is normally open when the rotary is in the home position and closed while the rotary dial is moving. Reading this second set of paddles will tell us when the dialing of a single number is complete. Finally, because we don`t know how long of a number the user is dialing, the PIC waits for a 4 second timeout before sending the given phone number to the GM862. This way the user can dial any type number of any length: 911, 3035551234, and 011212465748. The ringer circuit must use the 3. 7VDC nominal from the battery and output ~80VAC to get the coil to kick the hammer between 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.....
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