N.O. triggered sirin: what do I need to trigger on signal?

It's difficult to determine what you're trying to achieve. Can you provide a litt more detail?

I need to take a simple Normally open signal to switch on and off a low voltage supply.

When the signal circuit is grounded, the Low voltage circuit should be grounded to supply power.

Example : Infrared sensor detects heat, closes normally open contact - circuit takes signal and closes power - LED turns on, peso sounds, symbol playing monkey plays symbols.

Hi Pastor,

For safety sake you should have the low voltage supply powered from your mains using something like an AC adapter. This will isolate the high voltage from your system. Then the simplest arrangement would be to use a relay in series with your switch and low voltage power supply. The relay could then control a different circuit with a different voltage. If the voltage of your lights and cymbal monkey are the same as the low voltage circuit just eliminate the relay and put the cymbal monkey in series with the N/O switch and the power supply. Since I do not know your level of expertise it is difficult to describe in more detail. You mentioned an IR detector which would make the system more complicated as the sensor would need support circuitry to act as a proper switch. To get the best information you may want to check out these instructions for submitting a question that shabaz wrote to help with clarification of presented questions.

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John

The example of an IR sensor is the most likely scenario . I am pretty sure alarm contacts are designed to detect the resistance of the circuit using very low current most likely too low to trigger of a relay, and my main desire is to use standard alarm contacts as signal sources.

What would be needed to beef up the current to trigger a relay?

My knowledge is basic and burg and fire alarms on a technician level. I have zero engineering experience so I have no idea how to make these circuits and what parts I need to get the desired effect, yet am competent enough to understand and build from a diagram.

Hi Pastor,

Here are a couple of simple circuits. This first one will sound the alarm as long as the sensor switch is activated.

This second circuit will latch and continue to power the alarm until the Reset Switch is pushed. Both of these circuits use the same power supply for the sensor and the output device.

John

Hi Pastor,

Here is a circuit that I used to demonstrate the function of a Parallax Brand PIR (Passive Infra Red Sensor). The PIR in this circuit is powered with 5 volts and therefore a 5 volt voltage regulator 7805 is required. The sensor measures the temperature of its sensor area. Once the sensor field is stable the sensor will reset and the output will go to 0 volts. If the temperature changes due to someone or something moving in the sensor field the output of the sensor will go high to 5 volts and this in turn will turn on the MOSFET which will turn on the load. The alarm will sound until the sensor field is once again stable.

Newark listing of the PIR:

http://www.newark.com/parallax/555-28027/pir-sensor-180-degree-sensor/dp/11X5850?ost=Parallax+PIR&selectedCategoryId=&categoryName=All+Categories&categoryNameResp=All%2BCategories

Schematic of PIR Circuit:

John

Hi Pastor,

I had to hunt a little but I found a data sheet for the PIR that I used in my last circuit. I found it to be very stable and usable. There are cheaper ones from China but I found those to be flakey and not dependable.

https://www.parallax.com/sites/default/files/downloads/555-28027-PIR-Sensor-Prodcut-Doc-v2.2.pdf

John