K2: how can it work with the latched relays?

[Karsten Eppert (DK4AS)]

No doubt: ist works, but I have a question in mind. As far as I
understand, the latching relays are switched back and forth by short
pulses from the I/O-controller. But: how does the controller know the
initial stage of the relay in order to switch to the desired position?
How does the controller know the position of the relay after power
failure with complete controller-reset?

Please help a curious man!

73
Karsten
DK4AS
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[Vic K2VCO]

Karsten Eppert(DK4AS) wrote:
> No doubt: ist works, but I have a question in mind. As far as I
> understand, the latching relays are switched back and forth by short
> pulses from the I/O-controller. But: how does the controller know the
> initial stage of the relay in order to switch to the desired position?
> How does the controller know the position of the relay after power
> failure with complete controller-reset?

It looks to me as if the relays are set or reset by reversing the
polarity.  One side of all the relays are connected together and the
other sides go to IO controller ports.  By making all the ports high
except for one, the result is to apply a negative voltage to the one
connected to the low port, resetting it.  To set the same relay, all the
other ports are made low and its port is high.  In either case, the
current flowing through the other relays is insufficient to affect them.
  Ingenious, isn't it?
--
73,
Vic, K2VCO
Fresno CA
http://www.qsl.net/k2vco

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[Jack Brindle]

It's Elecraft magic!

Actually, it's not that difficult. We reset all the relays when a  
tune session begins, then adjust them as the magic algorithm  
proceeds. When the desired tune level is achieved, we save the relay  
state information in non-volatile memory for later use (next time we  
return to the band).

On Dec 10, 2006, at 9:05 AM, Karsten Eppert(DK4AS) wrote:

> No doubt: ist works, but I have a question in mind. As far as I  
> understand, the latching relays are switched back and forth by  
> short pulses from the I/O-controller. But: how does the controller  
> know the initial stage of the relay in order to switch to the  
> desired position? How does the controller know the position of the  
> relay after power failure with complete controller-reset?
>
> Please help a curious man!
>
> 73
> Karsten
> DK4AS

- Jack Brindle, W6FB
------------------------------------------------------------------------
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