Echolink Controller with DTMF Decoder
Deutsche Version


Circuit  (Target)
Circuit page 1 (png)
Circuit page 2 (png)
Layout (png)
Sourcecode for PIC16F84 (zip)
Sourcecode for PIC16F627 (zip)
Option: AGC amplifer (Target)
Option: AGC amplifier circuit (png)
Option: AGC amplifier layout (png)

Option for the receiver:
Squelch circuit (COR) (Target)
Circuit (png)
Layout (png)

Manual (pdf)
The radio ground is complete isolated from the computer ground. 
The  DTMF signals are decoded from the hardware.

Some features:

  • Transceiver is complete isolated from the PC

  • Real  RS232 signals

  • VOX  or COR (positiv or negativ logic selectable)

  • Transmitter PTT via optocoupler

  • Hardware DTMF decoding

  • Muting (automatic) of receiver audio

  • Variable audio tone control with an active op-amp circuit

  • Adjustable receiver and transmitter audio level

  • Power status, DTMF decoding and COR are monitored by LED's

  • No relays for switching, all switching is done by optocouplers

  • Usable for other digital modes like PSK31

  • With extra circuit board: AGC amplifier for the receiver audio

  • Free Sourcecode (assembler and hex code) for PIC16F84 or PIC16F627 (built with MPLAB 6.41 from Microchip)

  • Layouts and circuits are made with the pcb and layout CAD software Target 3001 (you can get a free demo version from Target here)