# How does this work?

#### NoviceChris

Joined Aug 11, 2018
22
Hello all.

Can anyone tell me how this works please?

Obviously the red and black is power to the sensor but when the sensor is activated, how does it become an active circuit or switch?

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#### AnalogKid

Joined Aug 1, 2013
8,251
How tall is the large black rectangle in the center of the receiver board? It might be a reed relay, in which case the white and yellow (or green) wires go to a single "Form A" contact set, which is SPST, normally open. The contacts close upon receipt of a valid signal.

ak

#### NoviceChris

Joined Aug 11, 2018
22
I have put a voltage tester on all cables when active.
Sensor activated:
Positive to green = no output
Positive to white = no output
Negative to green = no output
Negative to white = no output
Green to white = no output

Sensor in standby:
Positive to green = no output
Positive to white = no output
Negative to green = no output
Negative to white = no output
Green to white = no output

Simple talk please as I don’t know jargon or acronyms

What I want to achieve is a simple switching function. (Break the sensor = switch on)

#### ericgibbs

Joined Jan 29, 2010
9,343
hi Chris,
There will be no voltage output.
A pair of contacts are closed when active.
Do you have a resistance Ohms range on your test meter.??
E

#### ericgibbs

Joined Jan 29, 2010
9,343
hi Chris,
Try these two circuits.
One for resistance and one for a voltage output.
Do the Ohms test first.
E

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#### NoviceChris

Joined Aug 11, 2018
22

#### ericgibbs

Joined Jan 29, 2010
9,343
hi,
So when you measure the Ohms and then activate the receiver by pointing the transmitter at it, the contacts should close and the resistance meter reads almost zero Ohms when activated and greater than say 100K Ohms when not activated.
Can you check that out.?
E

#### Dodgydave

Joined Jun 22, 2012
8,677
I have put a voltage tester on all cables when active.
Sensor activated:
Positive to green = no output
Positive to white = no output
Negative to green = no output
Negative to white = no output
Green to white = no output

Sensor in standby:
Positive to green = no output
Positive to white = no output
Negative to green = no output
Negative to white = no output
Green to white = no output

Simple talk please as I don’t know jargon or acronyms

What I want to achieve is a simple switching function. (Break the sensor = switch on)
Ensure Jumpers J1, J2, are set the same on both transmitter and receiver,.

Put jumper onJ3, put power on, measure between Green/White it should read short circuit, when the unit receives a valid code signal, the relay operates and Green/White becomes open circuit .

Remove J3, and the Green/White are reversed, ( open circuit until a valid code received ).

#### NoviceChris

Joined Aug 11, 2018
22
hi Chris,
Try these two circuits.
One for resistance and one for a voltage output.
Do the Ohms test first.
E
Ohms read 1 when connected to white and green when transmitter is off (bream is broken) and drops to 0 when transmitter is on (bream is active and connected)
I’m guessing that means it’s an open circuit when beam is not broken?

#### NoviceChris

Joined Aug 11, 2018
22
Ensure Jumpers J1, J2, are set the same on both transmitter and receiver,.

Put jumper onJ3, put power on, measure between Green/White it should read short circuit, when the unit receives a valid code signal, the relay operates and Green/White becomes open circuit .

Remove J3, and the Green/White are reversed, ( open circuit until a valid code received ).
I’m sorry I don’t understand the jumper, j1,2,3 stuff? Can you explain so a 5 year old would understand. What is it for?

#### LesJones

Joined Jan 8, 2017
2,439
The jumpers select the frequency that modulates the transmitted infra red signal in the transmitter. In the receiver the jumpers select the centre frequency of the bandpass filter. If the transmitter is set to a different frequency to the receivers filter then it will not be recognised. The option to select different frequencies is so that units working close together do not interfere with each other. Think of it a bit like radio stations transmitting on different frequencies. You only receive the one that your radio receiver is tuned to.

Les.

#### NoviceChris

Joined Aug 11, 2018
22
The jumpers select the frequency that modulates the transmitted infra red signal in the transmitter. In the receiver the jumpers select the centre frequency of the bandpass filter. If the transmitter is set to a different frequency to the receivers filter then it will not be recognised. The option to select different frequencies is so that units working close together do not interfere with each other. Think of it a bit like radio stations transmitting on different frequencies. You only receive the one that your radio receiver is tuned to.

Les.
The same as using a radio transmitter for an alarm or similar when you select the codes by turning on/off the numbered switches.
What does nc/no mean?

#### sghioto

Joined Dec 31, 2017
1,038
What does nc/no mean?
NC means normally closed contact
NO means normally open contact
SG

#### NoviceChris

Joined Aug 11, 2018
22
NC means normally closed contact
NO means normally open contact
SG
Great. So I can reverse the circuit if I need to change it to constantly open or constantly closed. Thanks

#### sghioto

Joined Dec 31, 2017
1,038
Ohms read 1 when connected to white and green when transmitter is off (bream is broken) and drops to 0 when transmitter is on (bream is active and connected)
I’m guessing that means it’s an open circuit when beam is not broken
No. When the beam is not broken it's a closed circuit.
SG

#### sghioto

Joined Dec 31, 2017
1,038
Is this the detector you are planning on using for your other thread?
SG

#### NoviceChris

Joined Aug 11, 2018
22
Is this the detector you are planning on using for your other thread?
SG
No. This will activate something I built last year.

#### NoviceChris

Joined Aug 11, 2018
22
Thanks all. You have been a great help and very welcoming.