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Re: [TowerTalk] Gigavac Relays

To: <>
Subject: Re: [TowerTalk] Gigavac Relays
From: "Tod - ID" <>
Date: Fri, 31 Dec 2010 11:21:19 -0700
List-post: <">>
 Rick & Jim - so much old text it is hard to find the new stuff.

>From Jim's comments:

> &&  I did  notice that on any of these  26.5 vdc latching type
> the coil resistance on em is very low..and blows my 5A current limited lab

> supply into the red.  A quick pulse  of 12 vdc  is more than ample 
> to operate a 26.5 vdc  latching type  vac relay.
> later....... VE7RF
K0TO response => For me the simple solution was to put a series resistance
followed by a shunt cap across the supply leads to the relay. The cap
provides a quick burst of current and the series resistor limits the final
current. I allow just enough final current to 'warm' the remote relay coils
located at the base of the tower. [temp this morning in Idaho was 3 deg F]. 

Since the circuit can be built with current directing diodes, only one pair
of wires is required [actually n+1 for n co-located relays being
controlled]. The control line for each relay is switched between + and - to
change the latched state.

Tod, K0TO


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