Piezo sensor circuit

[BrianRD]

Schematics for two of the many alternate circuits to do this task. The upper one is a standard monostable followed by a logic-level N-channel power MOSFET, and everything runs on the lamp batteries. R3 can be changed to a pot for variable lamp on-time. The lower one is based on an oscillator/counter chip, with separate power for the timer and the lamp. These circuits assume the piezo makes at least 2 V or 6 V. If not, there are simple mods for lower input signals. Questions?

ak
View attachment 28284

Ak, thanks very much for these circuits. I would like to try and adapt the first one for a very specific project. I want to be able to detect, with high sensitivity, when a solid object (a croquet ball) hits a wooden upright peg. I have tried using a 555 timer chip with a sensitive switch but it works it lacks the sensitivity I need and it takes up too much room because of the relay etc.
Would it be possible to adapt your first circuit to do the following -
1) run with a 9 volt battery
2) light a 6 volt LED strip for a controlled length of time.
I have limited electronics experience so would welcome details of any component changes you would suggest.
3) I planned to use the Minisence 100 transducer
http://www.digikey.com/product-search/en?site=us&lang=en&Keywords=MSP6915-ND
Happy to provide more details and also use your second circuit if you think it would be better.
BRD

 

[AnalogKid]

Not the easiest sensor in the world to interface to. A typical interface circuit would be a nice starting point, but the data sheet doesn't have one. Other than that, not at all difficult. What is the current through the LED string, and lit up for how long?

ak

 

[BrianRD]

Not the easiest sensor in the world to interface to. A typical interface circuit would be a nice starting point, but the data sheet doesn't have one. Other than that, not at all difficult. What is the current through the LED string, and lit up for how long?

ak

I am happy to change the transducer in line with those described above in this thread. Not sure about the Led current but it must be small, the work off a standard 9 volt battery. I would have thought in the order of 50mA.
I would like the Led strip to light for 5-10 seconds.
BRD

 

[BrianRD]

Not the easiest sensor in the world to interface to. A typical interface circuit would be a nice starting point, but the data sheet doesn't have one. Other than that, not at all difficult. What is the current through the LED string, and lit up for how long?

ak

Hi AK
I have managed to work out that the LED strip draws 83 mA when using a 9 volt battery.
Could you advise if I need to alter any of the components in circuit 1. Many thanks for your help.
BRD