For my 70 cm setup (TS930 – MMT432/28 – LPM432/100) I had the need for a sequencer that generates the proper timing to switch all on/off in the correct order.

Top view sequencer
Top view sequencer

Since I could not find anything satisfactory, I decided to built something myself. The timing is straight forward:

Sequence Timing

When PTT becomes active, OUT0 will be activated, appr 50 mS, OUT1 will be activated and after another 50 mS OUT2 will become active. After releasing PTT, all outputs will be de-activated in reverse order with an delay of ~40 mS.

All outputs are open-drain (FET), the PTT input expects an open collector output from the transceiver, in my case this is a TS930.

The schematic is very straight forward, an ATMEL ATTINY45 programmed in BASCOM (available from is used to control the in- and outputs. Three BS170 (FET) are used as open drain output to control the transverter and PA, a third output was added but not needed for my setup.


Code is simple and can be obtained here:  seq004

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Internal view (top)
2013-11-03 15.41.48
Internal view (bottom)