Simple Lie Detector - Page 5 - Electronic Circuits Projects Diagrams Free

Roff · 9th October 2006, 10:25 PM

Quote:

Originally Posted by LeeMorgan

Thanks for the reply, Ron - I like your schematic alot. My class will be building these and your version will allow us to have smaller groups working on this since we will now have more power supplies to work with. I see how your particular circuit can be re-drawn to essentially be a wheatstone bridge circuit. However, I am still a bit stuck on how the original circuit can be represented this way with those two power supplies. Why did the designer feel that two power supplies were needed in this circuit?

They are equivalent as shown below. The designer may have used two batteries because he didn't feel any need to reduce the number of batteries, or didn't know how.

PS as Audioguru says, you can use 9V batteries.

sippi3000 · 27th October 2006, 01:31 AM

can some tell me why onc i power up my lie detector my meter is at full power so i cant measure resistance

Roff · 27th October 2006, 01:58 AM

Quote:

Originally Posted by sippi3000

can some tell me why onc i power up my lie detector my meter is at full power so i cant measure resistance

Post your schematic and we'll take a look at it. What is your meter's full scale current?

ismlamour · 4th November 2006, 02:30 PM

thans>>>>>>>>>>>>>>>>>>>>>>>>>

Science Mac · 11th November 2006, 06:37 PM

hello fellow people i wanted to see how to build the circuit because of the connection between the second resistor and the analog meter

Roff · 13th November 2006, 02:11 AM

Quote:

Originally Posted by Science Mac

hello fellow people i wanted to see how to build the circuit because of the connection between the second resistor and the analog meter

What does this mean? If you can't read a schematic, describe what you need to know in detail.

cheystar · 2nd January 2007, 04:21 PM

a noob question here. this circuit is placed on a board right? the ones with holes? Also wires used to connect each component is stranded 18 gauge insulated wire ok?

audioguru · 2nd January 2007, 04:42 PM

18 gauge wire is too big for the small holes in a circuit board.
Use 22 gauge solid tinned copper insulated hookup wires.

CuentaChocula · 28th January 2007, 08:00 AM

http://www.fairradio.com/catalog.php...item&item=4804

http://www.allelectronics.com/cgi-bi...EL_METER_.html

Please let me know if anyone found one cheaper.

nightcatz · 18th March 2007, 08:15 AM

hi ...electro master can I use s9014 in lieu of 2n 3565 ..pls help

Roff · 18th March 2007, 02:22 PM

Quote:

Originally Posted by nightcatz

hi ...electro master can I use s9014 in lieu of 2n 3565 ..pls help

S9014 will work just fine.

Peter_wadley · 25th March 2007, 05:23 AM

Great project!

nightcatz · 26th March 2007, 08:23 AM

hi guys can anyone tell me If I can use digital ammeter of the Digital Multimeter in lieu of the analog meter .......I dont have a analog meter in my place and allelectronics.com says it cannot ship the product to my place

audioguru · 26th March 2007, 08:48 PM

The lie detector project sometimes lies.
It measures the resistance of skin and the resistance of its connection to skin. It is supposed to use a 1mA moving coil meter so you can see the meter's needle move. A digital meter will just be a blur of changing numbers if anything changes.

nightcatz · 27th March 2007, 09:02 AM

thanks the info audioguru ......can u tell me if using the digital ammmeter can spoil the multimeter

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27th October 2006, 01:31 AM	(permalink)
sippi3000	can some tell me why onc i power up my lie detector my meter is at full power so i cant measure resistance

4th November 2006, 02:30 PM	(permalink)
ismlamour	thans>>>>>>>>>>>>>>>>>>>>>>>>>

11th November 2006, 06:37 PM	(permalink)
Science Mac	hello fellow people i wanted to see how to build the circuit because of the connection between the second resistor and the analog meter

2nd January 2007, 04:21 PM	(permalink)
cheystar	a noob question here. this circuit is placed on a board right? the ones with holes? Also wires used to connect each component is stranded 18 gauge insulated wire ok?

2nd January 2007, 04:42 PM	(permalink)
audioguru	18 gauge wire is too big for the small holes in a circuit board. Use 22 gauge solid tinned copper insulated hookup wires. __________________ Uncle $crooge

28th January 2007, 08:00 AM	(permalink)
CuentaChocula	Sources for the meter http://www.fairradio.com/catalog.php...item&item=4804 http://www.allelectronics.com/cgi-bi...EL_METER_.html Please let me know if anyone found one cheaper. __________________ Cuenta Chocula (Cuenta is my title)

18th March 2007, 08:15 AM	(permalink)
nightcatz	can I use any npn replacing the 2n 3565 hi ...electro master can I use s9014 in lieu of 2n 3565 ..pls help

25th March 2007, 05:23 AM	(permalink)
Peter_wadley	Great project! __________________ "Stick around" - Arnold Schwarzenegger in The Predator after impaling a soldier to a wood post 9vDC Guitar Pedal PSU PIC16F84a Game Module

26th March 2007, 08:23 AM	(permalink)
nightcatz	hi guys can anyone tell me If I can use digital ammeter of the Digital Multimeter in lieu of the analog meter .......I dont have a analog meter in my place and allelectronics.com says it cannot ship the product to my place

26th March 2007, 08:48 PM	(permalink)
audioguru	The lie detector project sometimes lies. It measures the resistance of skin and the resistance of its connection to skin. It is supposed to use a 1mA moving coil meter so you can see the meter's needle move. A digital meter will just be a blur of changing numbers if anything changes. __________________ Uncle $crooge

27th March 2007, 09:02 AM	(permalink)
nightcatz	thanks the info audioguru ......can u tell me if using the digital ammmeter can spoil the multimeter