My mobile rig, a Kenwood TM-D710E, needed a GPS receiver for APRS use. The GPS-710 wasn`t readily available and, besides, is quite expensive. I therefore decided to build my own. I found a Royaltek RGM-3600 GPS receiver on eBay for less than £20. This is a very good SiRF III based receiver. The magnetic case made a nice fridge magnet as only the
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bare module was needed. Although the listing didn`t mention it, this turned out to be the RS-232 version of the module. If it had been the TTL version, I would have needed an additional MAX232 level converter. The module pinout is available here. Bob WB4APR (yes, that Bob) has very helpfully provided the pinout of the RJ45 (okay, 8P8C) connector on the TM-D710 display head. It shows that pin 6 is ground and pin 7 is +10V. This is a handy place to leech a few tens of milliwatts for the GPS receiver. I decided that the easiest way to get access to the +10V pin is by repurposing a RJ45 Y adaptor. Apparently these splitters are sometimes used in ISDN installations. I bought mine from Maplin for £5. 99. The male end of the adaptor isn`t ideal for soldering but a little bit of work with a craft knife exposes the contacts enough to solder wires into them. Because the result is a bit fragile, I decided to cover the solder joints with epoxy. There are better adaptors that would be easier to tap into. The GPS requires a 5V power supply. I wanted to make sure the system draws as little power as possible, so I used a Recom R78 series switching DC-DC converter from Rapid. The R78 is a small self-contained device that`s pin compatible with the 78xx linear regulators so it`s trivially easy to use. I decided to add an optional input capacitor and blocking diode for extra protection. The whole assembly was then secured onto the Y adaptor...
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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