solid state sequencers

[VK3WE]

Hi all,

I'm currently using a DEMI sequencer which uses relays to switch. Whilst relays a generally reliable I'm always a little nervous every time the the sequencer is in operation when trying to protect expensive pre-amps. Anyone know of any "solid state" sequencer? or is this not really an issue?

maybe I should stop worrying?

thanks all,
de Rhett VK3VHF

[VK2KRR]

Hi Rhett

I have 2 sequencers I got for my 2 & 70 amps which I found I didn't require. I think I got them from SSB Electronics, im not sure. But if your interested in some more info let me know.

[VK4CDI]

Hi Rhett
I use the N6CA (ARRL?) sequencers. Easy to build and parts readily available. Uses switching transistors to operate preamps/amps/coax relays. Haven't lost a GaAsFET since I started using them.

Cheers
Phil VK4CDI

[VK4APN]

Hi all,

I'm currently using a DEMI sequencer which uses relays to switch. Whilst relays a generally reliable I'm always a little nervous every time the the sequencer is in operation when trying to protect expensive pre-amps. Anyone know of any "solid state" sequencer? or is this not really an issue?

maybe I should stop worrying?

thanks all,
de Rhett VK3VHF

I built my own version of the DEM sequencer - but changed the components a little to allow easier pcb layout. i.e. I used dual opamps and uln2003 relay driver ic. I have found mine very reliable to date - It really is a simple circuit that just works. Mine is all smd construction together with smd relays - I used omron 12v dpdt smd types that had good specs - I havent measured the timing but would guess about .5 sec to go thru complete sequence. I like to versatility of the design i.e. with up to 4 dpdt relays that are sequenced and can be NO, NC relative to either gnd or supply.
Cheap to build too!
Paul vk4apn

[VK4GHZ]

...Mine is all smd construction together with smd relays - I used omron 12v dpdt smd types that had good specs...

I wonder how good the isolation is, given the compact nature of these relays?

[VK4APN]

...Mine is all smd construction together with smd relays - I used omron 12v dpdt smd types that had good specs...

I wonder how good the isolation is, given the compact nature of these relays?

The relays are only switching relatively small dc voltages or shorting to deck or supply? - well within their specs. Not sure what you mean by "isolation" as the sequencer just supplies dc or zip - as required to my masthead mounted coaxial relays (tohtsu cx120p pcb mounted) and easily changable preamp. If I ever use to switch mains equip will use onboard relay to switch mains rated relay .

Do you think there could be a problem using these smd relays? Would be interested to know.

Thanks

paul vk4apn