Mast Lamp Keyer

For the Mast lamp keyer you will need:

1 x 24V 35W switched mode PSU
1 x Atmel ATTINY13A micro-controller
1 x 8 pin IC socket
1 x 78L05 5V 100mA regulator
2 x 100nF caps (decoupling)
1 x 330R resistor
1 x low current LED
1 x IRF520 MOSFET
Veroboard
Hook-up wire

I use 24V DC for lamps and relays in the station as its twice the
voltage half the current and 1/4 the volts drop in the wiring. 24V lams
and 24V relays are cheap as most hams want only 12V powered gear!

Circuit is very simple!  Port PB0 is configured as an output and drives
the LED directly and an N-channel MOSFET which switches the negative
side of the lamp.

mastlamp keyer

The code is very simple! No interrupts or fancy timing, just use the
run-time’s blocking wait/delay _delay_ms() from a wrapper function.
Morse is spelled out long-hand with dit() and dah() functions performing
key_down() and key_up() with the necessary delays.

Mast Lamp Keyer.c

The MOSFET needs a heatsink.

You’ll need a second bit of Veroboard with an 8-ping IC socket, 5V
regulator and 6-pin ISP header (3×2 0.1″ header) to pop the chip in to
and program it from AVR Studio.

Mike G8TIC



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