Com port keyer circuits
Simple Interface for Handheld Radios
![Picture](/uploads/8/8/6/7/8867854/9008115.jpg)
A handheld’s mic and PTT are normally combined, hence circuit 3 was designed.
Audio levels can only be adjusted by the computer’s level control.Stereo 3.5 mm plugs connect the line in and out on the computer soundcard. Use the tip and earth only as, in this application, the sleeve is not used.
Components
Audio levels can only be adjusted by the computer’s level control.Stereo 3.5 mm plugs connect the line in and out on the computer soundcard. Use the tip and earth only as, in this application, the sleeve is not used.
Components
- 3 x 2.2k ¼ watt resistors .
- 1 x 10k ¼ watt resistor .
- 3 x 0.01uF capacitors.
- 1 x Red LED.
- 1 x Diode 1N4148 2 x 3.5mm Stereo plugs.
- 1 x BC108 Transistor.
- 1 x 9 Pin D plug ( Com port 1 or 2) & cover
- Screened Cable.
- Project Box.
Simple Interface
![Picture](/uploads/8/8/6/7/8867854/9801936.jpg)
Components
- 1 x 1k ¼ watt resistors.
- 2 x 2.2k ¼ watt resistors.
- 1 x 1k Potentiometer Lin.
- 1 x 2.2uF 50v capacitor.
- 4 x 0.01uF capacitors.
- 1 x Red LED (High sensitivity type).
- 2 x Diode 1N4148.
- 2 x 3.5mm Stereo plugs.
- 1 x BC108 Transistor.
- 1 x 9 Pin D plug ( Com port 1 or 2) & cover
- Screened cable.
- Project Box.
Isolated Interface
![Picture](/uploads/8/8/6/7/8867854/7118749.jpg)
Components
- 3 x 1k ¼ watt resistors.1 x 1.2k ¼ watt resistors.
- 1 x 1k Potentiometer lin. 1 x 2.2uF 50v capacitor. 3 x 0.01uF capacitors
- 2 x (T1 & T2) 600 ohm transformers type 9000 RS Number 208-822
- 1 x IC1 optocoupler 4N25 RS Number 597-289
- 1 x Red LED (High sensitivity type).
- 1 x Diode 1N4148.
- 2 x 3.5mm Stereo plugs
- 1 x 9 Pin D plug ( Com port 1 or 2) & cover
- Screened cable.
- Project Box.
Click to see PDF
![Picture](/uploads/8/8/6/7/8867854/1718467.gif)
Com port keyer circuits PDF