simple touch sensor

schematic: http://www.inbarhovav.com/2011/01/simple-touch-sensor.html
base on LM555
make by Inbar Hovav -

Category:

Howto & Style

Tags:

• simple
• touch
• sensor
• LM555
• 555
• inbar
• hovav
• inbarhovav

[jtcressy1]

i bet that you are touching ground with another finger while you touch that pin.

[inbarhovav]

@jtcressy1

pin 2 is very sensitive, you don't need to touch at the ground to activate it.

[jtcressy1]

@inbarhovav

It just doesn't work for me, unless I ground myself, like to the metal of my computer first, and then it sometimes doesn't trigger it. the only way to get it working right is to touch ground and the pin at the same time. I've even hooked up a logic probe to pin 3, in case the signal is too weak. still nothing from there. actually, does it matter how long the wire is? mine might be too long, but i'm just wondering.

[inbarhovav]

@jtcressy1

Could be that your finger is too dry, To increase the sensitivity try to remove the resistor R1 (10M ohm), or change it to a bigger resistor if it is to much.

The working principal of this circuit is that touching pin 2 will introduce noise into the input of the LM555 and the LM555 will be in a state of saturation and will remain so for the length of time defined by C1 (0.01 uf)

[matstermind]

schematic?

[inbarhovav]

@matstermind

You can find schematic at the description of this video.

[inbarhovav]

@cassianorabelo

all the capacitors in the movie is 0.01 uF

but you can make a delay if you put bigger capacitors between legs 6,7 to the GND

and leave the 0.01 uF between legs 5 to the GND

Inbar

[cassianorabelo]

Nice! Do you mind telling the values of the capacitors?

[luisfable]

@SAMEDOKAWA cof cof datasheet cof cof

[luisfable]

@inbarhovav lol i make it that circuit for accident when im tryng to make a counter xD

nice job :p