A N2PK VNA that it would be useful for antenna measurements and wanted to run it with a laptop PC. As most newer laptops do not have a parallel port on them I decided to explore running it off the USB port. USB has its attractions when it works properly and the idea of making the VNA plug and play appealed to me. My initial thoughts were to try using a standard
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USB to parallel port cable. The problem I found with one of these devices was that WinXP insisted on identifying it as a printer and set it up as a USB printer. No doubt there is a way round this if you know more about the operation of the USB port than I do. Having found that this approach was not going to work easily I bought one of the Elrasoft Cypress EZUSB modules described on Dave Robert`s, G8KBB, website. I followed the instructions to program the chip with the correct PID and VID for the VNA application having downloaded the EZUSB control panel from Cypress`s website. All that remained to do was to let the PC detect the USB board and wait for it to ask for the drivers etc for the VNA which I had already downloaded from Dave`s website. Once the installer program was pointed at the folders with the *. inf files all went smoothly. Having made the VNA communicate over the USB bus my thoughts turned to powering it from the bus. A USB port can provide 5 V at around 500 mA. A quick check with a multi-meter showed that the VNA only took about 200mA from its 5 V supply. The VNA also requires a nominal +12 V supply which is used to power a 7661 voltage inverter chip. This is used to generate a low powered -5 V supply on the VNA PCB. The 12 V is clearly not very critical and anywhere above about 7-8 volts seemed adequate. The problem was to find a way of producing 9-10 volts from the 5 V USB supply. The solution was to use...
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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