A small pulse

alnajjar1

Hello,

I am making an exhibit for our Museum using a standard sink with an IR faucet. The faucet works. When the hand passes in front of it, the solenoid controlling the water is activated for about 10 second. Measuring the voltage to the solenoid, it is a very short pulse (much less than a second) of about 1V. I went to the length of using a BS2, amplify the signal with a transistor etc, but that is way too complicated. All I want to do is: when the sensor is triggered, a contact relay is triggered for about 1 second to turn on a digital audio player.

Any idea how to do this without the stamp? When I use the stamp, the voltage is low and the BS2 misses the reading even if the signal is amplified.

thanks for any help,

Al

Phil Pilgrim (PhiPi)

A 555 configured as a one-shot should be able to do what you want.

-Phil

ElectricAye

I'm going to take a wild guess that the power going to the solenoid valve is lined up something like this:

(6 volt to 24 volt power supply)

---

(solenoid)

---

(current limiting resistor)

---

(transistor or relay switch of some sort)

---

(Ground).

or maybe:

(6 volt to 24 volt power supply)

---

(transistor or relay switch of some sort)

---

(solenoid)

---

(current limiting resistor)

---

(Ground)..... etc.


If my guess is correct, then you're measuring only 1 volt across your solenoid, yet you might still be able to tap into that circuit someplace else where the voltage is higher, for example across the current limiting resistor. Or get a better signal between someplace in the circuit and ground. Might this be the case?