Modified from: https://github.com/dhakajack/jackyack
Arduno ATTint85 chip gives you 4 x 100char memories, iambic a, b and ultic also provides a training program. All this on a chip costing < £2!
ATtiny85
+-------- --------+
PB5 -|1(RST) |_| 8|- VCC
DIT <-- PB3 -|2 (SCK)7|- PB2 --> CMD BTN -------- GND
DAH <-- PB4 -|3 (MISO)6|- PB1 --> PIEZO --------- GND
GND -|4 (MOSI)5|- PB0 --> TX OUT
+-----------------+
I have put this is a small case and added 10pF capacitors to all the socket pins to ground ( and button) to stop stray RF. Initially, this just used a MODFET 2N7000 to switch low the keying line however I do have a old Hybrid transceiver (TS530SP) which needs to key the -75V screen grid. I added that by using a high-voltage PNP transistor and used diodes to block the two keying outputs from each other. This has been tested and works a treat and saves on the expense of a solid-state relay.
I also run it off the 13.5V radio supplies through an LM7805 voltage regulator.
