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AC powered OR gate??

J

Jim Thompson

Jan 1, 1970
0
Hi,

I have a load, which is a lamp of 240V and 50W, I need 2 sensor to drive it.
Both sensors are 240V powered and output is 240V.
How do I create an OR gate for this AC driven device so that if any one of
the sensor is triggered, the lamp will light up? I can't join both output
together as it will blown by the back fire if one output is high (240V) and
the other is OFF.

Appreciate if you could send your suggestion to [email protected] as I
seldom have access to newsgroup..thanks

Use a relay on each "sensor" output... parallel the poles to get the
"OR" function.

...Jim Thompson
 
A

Alex C

Jan 1, 1970
0
Hi,

I have a load, which is a lamp of 240V and 50W, I need 2 sensor to drive it.
Both sensors are 240V powered and output is 240V.
How do I create an OR gate for this AC driven device so that if any one of
the sensor is triggered, the lamp will light up? I can't join both output
together as it will blown by the back fire if one output is high (240V) and
the other is OFF.

Appreciate if you could send your suggestion to [email protected] as I
seldom have access to newsgroup..thanks
 
J

Jim Thompson

Jan 1, 1970
0
another question, do I need to put a rectifier across the terminal as in DC
operated relays to absorb the high current dischage when the relay is switch
off?
[snip]

You need to tell us more about your "sensor".

...Jim Thompson
 
A

Alex C

Jan 1, 1970
0
pardon me for my ignorant... there is 240V powered solenoid relay in
electronics shop? oh... all along I've using only up to 24V solenoid
relays...

ok, will try the suggested method

thanks Jim!
 
A

Alex C

Jan 1, 1970
0
another question, do I need to put a rectifier across the terminal as in DC
operated relays to absorb the high current dischage when the relay is switch
off?
 
T

Tim Wescott

Jan 1, 1970
0
Alex said:
pardon me for my ignorant... there is 240V powered solenoid relay in
electronics shop? oh... all along I've using only up to 24V solenoid
relays...

ok, will try the suggested method

thanks Jim!
-snip-

That depends on what shop you frequent. There are 240V AC relays
available from industrial suppliers. In the US I'd look at Granger or
possibly McMaster-Carr.
 
T

Tam/WB2TT

Jan 1, 1970
0
Alex C said:
Hi,

I have a load, which is a lamp of 240V and 50W, I need 2 sensor to drive
it.
Both sensors are 240V powered and output is 240V.
How do I create an OR gate for this AC driven device so that if any one of
the sensor is triggered, the lamp will light up? I can't join both output
together as it will blown by the back fire if one output is high (240V)
and
the other is OFF.

What does OFF mean? Is it an open circuit, or is it switched to the other
side of the line?

Tam
 
J

Joerg

Jan 1, 1970
0
Hi Alex,
another question, do I need to put a rectifier across the terminal as in DC
operated relays to absorb the high current dischage when the relay is switch
off?
If everything you use including the relays is made for 240V AC then you
don't need any rectifiers. 240V AC relays should be easily found at a
larger electrician's supply house. At Digikey you can mail order 240V AC
relays.

Regards, Joerg
 
A

Alex C

Jan 1, 1970
0
I'm not sure what if the state of the output from the sensor when it's
"OFF"...it could be floating.
 
N

N. Thornton

Jan 1, 1970
0
Jim Thompson said:
Use a relay on each "sensor" output... parallel the poles to get the
"OR" function.

...Jim Thompson

Or you can just connect them both together, having _ensured_ you got
the polarity right.

NT
 
T

Tam/WB2TT

Jan 1, 1970
0
Alex C said:
I'm not sure what if the state of the output from the sensor when it's
"OFF"...it could be floating.

If the OFF sensor is floating, you should be able connect the two sensor
outputs in parallel, provided they are on the same phase.NT mentioned that
also. There is also the chicken's way. Connect a diode from each of the
sensors to a common power resistor connected to a 48V DC relay. You might
need a small (~1 ufd) capacitor to keep the relay from chattering. A third
diode goes across the field of the relay.

Tam
 
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