12 Volt human body to human body touch circuit help

Thread Starter

Anubhav Sharma

Joined Mar 21, 2016
68
Hi everyone,
You guys are really great, with you perfect guidance I have always achieved my goal.
This time I need your help again, I have to design a circuit for an educational project which shows the resistance and energy capability of the human body. Something like "Human Electricity Energy Stick Circuit" in which two humans touch two ends or two touch plates and while holding touch plates when they both touch each other, the circuit starts to flow current.
Need to design this for 12v relay with 12v 2amps supply.

Please help with this circuit, this is for Rural development and human body awareness.
Thanks in advance, looking forward to your help.
 

Thread Starter

Anubhav Sharma

Joined Mar 21, 2016
68
Hi everyone,
I need your help regarding the touch circuit I made with some available schematics on the web.
Please see the circuit schematics as an attachment.

When I tried same schematics on a breadboard it was working fine without using a 12v relay, only with led and buzzer.
Now when I etched a PCB of the same design, it's behaving abnormally, this time am using a 12v relay in place of the buzzer.

the purpose is to create two touch points on different sides, so when two people together touch each point and then touch each other the relay should trigger. BUT, instead of touching both points the relay triggers by only touching VCC side of a touch point.
in actual, the negative and positive sides ( the two touch points) must be touched in order to trigger the relay...

I am using NE555, 10uf 450v electrolytic cap.

Please help with this, ill be really thankful
 

Attachments

Thread Starter

Anubhav Sharma

Joined Mar 21, 2016
68
Hi everyone,
I need your help regarding the touch circuit I made with some available schematics on the web.
Please see the circuit schematics as an attachment.

When I tried same schematics on a breadboard it was working fine without using a 12v relay, only with led and buzzer.
Now when I etched a PCB of the same design, it's behaving abnormally, this time am using a 12v relay in place of the buzzer.

the purpose is to create two touch points on different sides, so when two people together touch each point and then touch each other the relay should trigger. BUT, instead of touching both points the relay triggers by only touching VCC side of a touch point.
in actual, the negative and positive sides ( the two touch points) must be touched in order to trigger the relay...

I am using NE555, 10uf 450v electrolytic cap.

Please help with this, ill be really thankful
 

Attachments

AlbertHall

Joined Jun 4, 2014
10,541
Your body will pick up the 50/60Hz signal from the mains. when you touch the pas connected to the '555 trigger input it will trigger the '555 as the '555 input is high impedance and the only other component is a 10MΩ resistor.
You could try a capacitor across the touch pads to bypass the mains signal - perhaps 100nF or 1uF.

[EDIT] The problem is likely to be better if the circuit is powered by battery and worse if it is powered by a switch-mode wall wart.
 

ArakelTheDragon

Joined Nov 18, 2016
1,350
Your body will pick up the 50/60Hz signal from the mains. when you touch the pas connected to the '555 trigger input it will trigger the '555 as the '555 input is high impedance and the only other component is a 10MΩ resistor.
You could try a capacitor across the touch pads to bypass the mains signal - perhaps 100nF or 1uF.

[EDIT] The problem is likely to be better if the circuit is powered by battery and worse if it is powered by a switch-mode wall wart.
And if one of the contestants has a bypass?
 

Thread Starter

Anubhav Sharma

Joined Mar 21, 2016
68
Your body will pick up the 50/60Hz signal from the mains. when you touch the pas connected to the '555 trigger input it will trigger the '555 as the '555 input is high impedance and the only other component is a 10MΩ resistor.
You could try a capacitor across the touch pads to bypass the mains signal - perhaps 100nF or 1uF.

[EDIT] The problem is likely to be better if the circuit is powered by battery and worse if it is powered by a switch-mode wall wart.
Thanks am now going to connect the cap.
The circuit is powered by 12v 2amp smps, i have already tried 12v battery the results are same.
 

Thread Starter

Anubhav Sharma

Joined Mar 21, 2016
68
Your body will pick up the 50/60Hz signal from the mains. when you touch the pas connected to the '555 trigger input it will trigger the '555 as the '555 input is high impedance and the only other component is a 10MΩ resistor.
You could try a capacitor across the touch pads to bypass the mains signal - perhaps 100nF or 1uF.

[EDIT] The problem is likely to be better if the circuit is powered by battery and worse if it is powered by a switch-mode wall wart.
As per your suggestion, I have added the 1uf cap across the two plates, I THINK THIS WORKED.
but there is a problem again, it is now taking 3 to 5 seconds to trigger, I guess its a long time.
can you help me rectifying this delay, I mean as per project requirement the circuit should trigger within 1 second or max 2 seconds.

again, thanks for your help.
 
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