SENSOR

Sensor adalah peralatan yang digunakan untuk merubah suatu besaran fisik menjadi besaran listrik sehingga dapat dianalisa dengan rangkaian listrik tertentu. Hampir seluruh peralatan elektronik yang ada mempunyai sensor didalamnya.

Pada saat ini, sensor tersebut telah dibuat dengan ukuran sangat kecil dengan orde nanometer. Ukuran yang sangat kecil ini sangat memudahkan pemakaian dan menghemat energi.

Mau tahu dasar-dasarnya,

Sirkuit elektronika yang lain

SOUND OPERATED SWITCH

Notes:
This sensitive sound operated switch can be used with a dynamic microphone insert as above, or be used with an electret (ECM) microphone. If an ECM is used then R1 (shown dotted) will need to be included. A suitable value would be between 2.2k and 10kohms.
The two BC109C transitors form an audio preamp, the gain of which is controlled by the 10k preset. The output is further amplified by a BC182B transistor. To prevent instability the preamp is decoupled with a 100u capacitor and 1k resistor. The audio voltage at the collector of the BC182B is rectified by the two 1N4148 diodes and 4.7u capacitor. This dc voltage will directly drive the BC212B transistor and operate the relay and LED.It should be noted that this circuit does not "latch". The relay and LED operate momentarily in response to audio peaks.

ELECTRONIC NIGHT LIGHT

Notes:
This circuit was submitted by Adam from Canada who is still at school. I have provided the text. The two transistors are used as a direct coupled switch, Adam used 2SC711 but any general purpose transistor will do e.g. 2N3904, BC109C.
The CDS photocell, type ORP12 is normally illuminated, therefore its resistance is low. The 50k control, the 1k resistor and the photocell form a potential divider which biases the first transistor. This transistor is on, its collector being held low, turns the last transistor and hence lamp and relay off.
In darkness, the resistance of the photocell becomes high and the first transistor switches off. The base voltage for the second transistor goes high, switching this transistor on and illuminating the lamp.Although Adam used a secondary supply of 3V , you could use any voltage and any lamphere. Make sure the relay contacts can handle the load. If using a large relay, it is preferable to wire a 1N4001 in reverse polarity across the coil. This will prevent the back EMF of the relay from damaging the transistors.

REMOTE DOORBELL WARNING SWITCH

Description:
This circuit will light a lamp at a remote location when the doorbell switch is pressed. This circuit should only be used with the solenoid type doorbells, the electronic type that play tunes will not work here.

Notes
It is quite easy to miss the sound of a doorbell if you are watching TV , this circuit gets round the problem by providing a visual indication. As an alternative, a LED could also be used. You could just parallel a lamp across the doorbell, but this would mean extra drain from the doorbell batteries or transformer.

A series resistor, R1 is wired in series with the doorbell and reduces current flow, thereby increasing battery life. The value of R1 is chosen so that about 0.6 to 0.7 volts is developed across it, when the doorbell switch is pressed. I used a combination of a 22 ohm resistor in parallel with a 50 ohm. The voltage drop across R1 is sufficient to switch on the transistor, the lamp in series with the collector will then illuminate. I also used an electromechanical counter in parallel with the lamp. This registered each time someone pressed the switch....in fact, I can remember a time when I had more "hits" on my doorbell counter then at my web site :)

LIGHT DETECTOR CIRCUIT

Notes:
Variable resistor R1 adjusts the light threshold at which the circuit triggers. R1's value is chosen to match the photocells resistance at darkness. The circuit uses a CMOS 4001 IC. Gate U1a acts as the trigger, U1b and c form a latch. S1 resets the circuit. The output device may be a low power piezo buzzer.

WATER ACTIVATED RELAY

NOTE:
Ovaj sklop je projektiran da ukljuci relej kada se na knotaktima pojavi voda.Tranzistor T1 moze biti zamijenjen s 2N2222A.Tranzistor T2 mora biti BC108. Na kolektor tranistora T1 osim releja mogu biti spojeni signal injektor, LE dioda, zarulja i ostali signalizacijski elementi.

In his circuit Marin has used two transistors wired as a high gain compound pair. Transistor T1 may be a 2N2222A and T2 a BC108. The current gain will be the product of each transistors beta, which will be a minimum of 140 x 110 or 15400. The power supply used can be any voltage from 4.5 to 15 volts, a typical 5 volt relay may require 60 mA to operate, in which case any fluid which passes a minimum current of 4 uA will activate the relay. This is easily achieved with tap or rain water.

DARK AKTIVE SWITCH OR PORCH LIGHT

This circuit will activate a relay when light falls to a preset level. Light level can be adjusted with VR1 and the relay contacts may be used to operate an external light or buzzer