Conrad Course material 10107 14 years and over 10107 User Manual
Product codes
10107
3.3 Love Tester
The Love Tester is a little example with which two people can test if they are feeling the same thing. For this, the persons must hold two
contacts each in their hands and think of each other. If only the green LED lights up, both candidates are thinking of their partner. If one
person is currently thinking of something else and getting moist hands due to his or her bad conscience, the red or yellow LED will light
up.
R2
R2
R1
R1
V1
V1
V2
V2
V3
V2
T1
T1
T2
T2
Fig. 15: Pinboard setup Love Tester
Circuit Description
The two transistors are controlled via the skin resistance. The lower it is, e.g. due to moister hands, the more strongly will the transistor
be passed and the lower will the resistance of the collector-emitter route be. If the transistor resistance drops, more current can flow
and the light emitting diodes can light up more brightly. The maximum current through the light-emitting diodes is limited by the
dropping resistors R1 and R2. If the skin resistances are equal, the transistors will be controlled equally strongly and the voltage drop
across the collector-emitter route is the same. This will not cause a voltage drop at the light emitting diodes V1 and V2, which will
remain dark. Since the green LED is switched between the emitter and ground, it will always light once the transistors become
conductive.
be passed and the lower will the resistance of the collector-emitter route be. If the transistor resistance drops, more current can flow
and the light emitting diodes can light up more brightly. The maximum current through the light-emitting diodes is limited by the
dropping resistors R1 and R2. If the skin resistances are equal, the transistors will be controlled equally strongly and the voltage drop
across the collector-emitter route is the same. This will not cause a voltage drop at the light emitting diodes V1 and V2, which will
remain dark. Since the green LED is switched between the emitter and ground, it will always light once the transistors become
conductive.
R1
R1
R2
R2
3,3k
3.3k
rt
rt
ge
ge
V1
V1
V2
V2
V3
V3
gn
gn
T1
T1
T2
T2
E
E
Hautkontakte
Skin contacts
Fig. 16: Circuit diagram Love Tester