Archive for the tag 'EEPC 900'
I wanted to build a small APRS station, based on UIView and AGWPE for software, a small netbook latest el'ausilio a small handheld VHF.
The first problem is presented for interfacing with the RTX Handheld Netbook (an ASUS Eee PC 900), this fact was not equipped with serial interface but only the latest USB ports.
As a first step I bought a small cable conversion USB/RS232, so I researched on the Internet schemino one that allowed me to interface my handheld RTX (a Yaesu VX150) with sound card and netbooks to drive the PTT to send the radio transmission.
Wiring wheel
The Yaesu VX150 also had another small problem, unlike other parts that are separate from the microphone output sound, it has only one connector, namely a 3.5 mm jack with four contacts.
The mass comes together, the sound has a separate contact, but the microphone and the PTT contact have in common.
Small problem quickly solved by consulting the manual providing apparatus for attaching a small pattern of the same packet to a modem and can be profitably used again.
Only two components, a resistance of 2 kOhm and an electrolytic capacitor uF/16Volt 10, are sufficient, so if you want to adapt the scheme to other RTX, these two components will be derived from the user manual in your possession. 
For the rest there is really little to say, two resistors and two diodes usually 2N2222A transistor to drive the PTT can also be used in place of a photocoupler transistor I used to keep separate the masses (PC and RTX) but at this point should also use two transformers type phone to do the same on the audio, otherwise frustrate all.
The interface can be used on all systems with input four-pole like Yaesu, but is easily adaptable to other RXTX, I personally have tried it with the VX series and FT60. 
Notice in the photo above that I housed the two LEDs (red and green) that we report respectively the transmission and reception in the RS232 connector.
Given the absolute lack of insulation between the mass of the radio and the PC, not recommended for use in base station, another recommendation is the adoption on the cables carrying the signal of a ferrite falls to inhibit RT, unless use low transmission power.
schematic
