Relay
Stu Lyon
w6cux at EARTHLINK.NET
Tue Oct 18 20:36:29 EDT 2005
To further pursue this subject, look at the data sheet for the P&B K10
relay:
110VDC coil 11,000 ohms 10 mA
120VAC coil 3,900 ohms 11 mA
ref: http://relays.tycoelectronics.com/datasheets/K10_DS.pdf
Since it's amp-turns that operate a relay, the 120VAC relay should draw
the correct current at about 42VDC. (3.9K *11mA)
Back where we started from, a suitable relay for Martin might be found
from Mouser:
http://www.mouser.com/catalog/623/1238.pdf
Stu W6CUX
Allen Jones wrote:
>No expert on this stuff but found the following in the
>Collins Collectors Archive from 2002:
>
>"When an AC relay is used on AC the coil resistance
>and inductance set
>the coil current. When the same relay is used on DC
>the current will be
>higher as the reactance will not have any current
>limiting effect. If
>this relay is operated for long periods, the coil will
>get really hot.
> In amateur service where the on - off ratio is
>generally low the coil
>will not be on long enough to matter. If you are long
>winded or running
>RTTY, put some additional resistance is series with
>the coil to get the
>current back to the original value. You will need to
>determine the AC
>current either from data sheets for the relay or by
>measurement."
>
>I know from experience that a 12V AC relay run off of
>DC will get HOT if energized for several minutes at a
>time.
>
>My observation, your mileage may vary.
>
>73,
>
>Allen, W9DZ
>
>
>
>
>
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