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tof
Guest
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 Posted:
Wed Feb 16, 2005 4:42 pm Post subject:
Negative voltage tolerent relay ? |
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Hello
Does it exist some relay which accepts (is tolerant) a negative input
voltage without modifying the contact. In fact I want to make a
alternative signal go through a relay. Is is possible ? How can I do
it ?
Thanks
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Guest
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| Posted:
Wed Feb 16, 2005 7:32 pm Post subject:
Re: Negative voltage tolerent relay ? |
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chris-tof@ifrance.com (tof) wrote:
| Quote: | Does it exist some relay which accepts (is tolerant) a negative input
voltage without modifying the contact. In fact I want to make a
alternative signal go through a relay. Is is possible ? How can I do
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Relay contacts are not polarity sensitive. They may have different
ratings for AC versus DC, but they don't care aout polarity... |
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Jorgen Lund-Nielsen
Guest
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| Posted:
Thu Feb 17, 2005 12:33 am Post subject:
Re: Negative voltage tolerent relay ? |
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William, P.N., Smith schrieb:
| Quote: |
chris-tof@ifrance.com (tof) wrote:
Does it exist some relay which accepts (is tolerant) a negative input
voltage without modifying the contact. In fact I want to make a
alternative signal go through a relay. Is is possible ? How can I do
Relay contacts are not polarity sensitive. They may have different
ratings for AC versus DC, but they don't care aout polarity...
|
So it is if it's a mechanical relay.
But today there are also optoelectronical working "relays"
which are also called only relays, sometimes without the hint that they
are electronically/optically working (optocouplers in all kind of
function,
outputstages ("contact") varies from transistors to fets
(junction- and MOS-Fets) to triacs and so on.
In that case they are polarity sensitive.
(there are also AC-Versions at input ("coil") and output)
Maybe chris-tof means such a semiconductor-relay.
Jorgen
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Watson A.Name - \"Watt Su
Guest
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| Posted:
Thu Feb 17, 2005 6:10 am Post subject:
Re: Negative voltage tolerent relay ? |
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"Jorgen Lund-Nielsen" <jorgen.lund-nielsen@xxxxxxxxxxxdesy.de> wrote in
message news:421391E4.BA3ADE1C@xxxxxxxxxxxdesy.de...
| Quote: | William, P.N., Smith schrieb:
chris-tof@ifrance.com (tof) wrote:
Does it exist some relay which accepts (is tolerant) a negative
input
voltage without modifying the contact. In fact I want to make a
alternative signal go through a relay. Is is possible ? How can I
do
Relay contacts are not polarity sensitive. They may have different
ratings for AC versus DC, but they don't care aout polarity...
So it is if it's a mechanical relay.
But today there are also optoelectronical working "relays"
which are also called only relays, sometimes without the hint that
they
are electronically/optically working (optocouplers in all kind of
function,
outputstages ("contact") varies from transistors to fets
(junction- and MOS-Fets) to triacs and so on.
In that case they are polarity sensitive.
(there are also AC-Versions at input ("coil") and output)
Maybe chris-tof means such a semiconductor-relay.
|
The term relay is reserved for magnetic, mechanical contact type relays.
The SSR (solid state relay) is called that in order to tell it apart
from the mechanical relay. Other such things are _not_ called relays,
but optoisolators, etc.
> Jorgen |
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Guest
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| Posted:
Thu Feb 17, 2005 10:33 pm Post subject:
Re: Negative voltage tolerent relay ? |
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tof wrote:
| Quote: | Hello
Does it exist some relay which accepts (is tolerant) a negative input
voltage without modifying the contact. In fact I want to make a
alternative signal go through a relay. Is is possible ? How can I do
it ?
Thanks
For the coil, you can use a bridge rectifier to |
"steer" the voltage, assuming you can tolerate
the voltage drop. That "steering" would be
needed on electro-mechanical relays that have a
built-in protection diode.
The contact(s) don't care about polarity.
If you are not talking about an electro-mechanical
relay please let us know.
Ed |
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