Wiring Diagram

Circuit operation is as follows. The 555 timer is set up as a multi-vibrator 12hz. The output on pin 3 drives the 4027 flip-flop. This flip-flop divides the input frequency by two and delivers complementary voltage outputs to pin 15 and 14. The outputs are connected to LED1 and LED2 through the current limiting resistor R3. The LED's are Arranged so Pls That the polarity across the circuit is one way only one LED will from light and Pls the polarity reverses the other LED light earnest, therefore Pls no transistor is connected to the tester the LED's will from alternately flash. Also The 4027 outputs are connected to resistors R4 and R5 with the junction of these two resistors connected to the base of the transistor being tested. With a good transistor connected to the tester, the transistor will of turn on and Produce a short across the LED pair. If a good NPN transistor is connected then LED1 will from flash by Itself and if a good PNP transistor is connected then LED2 will from flash by Itself. If the transistor is open both LED's will from flash and if the transistor is shorted then neither LED will from flash.

The circuit on the left is a common collector or emitter follower and has the advantage of one less part since a resistor is not needed in series with the transistor base. However the voltage across the relay coil will be two diode drops less than the supply voltage, or about 11 volts for a 12.5 volt input.

The common emitter configuration on the right offers the advantage of the full supply voltage across the load for most of the delay time, which makes the relay pull-in and drop-out voltages less of a concern but requires an extra resistor in series with transistor base. The common emitter (circuit on the right) is the better circuit since the series base resistor can be selected to obtain the desired delay time whereas the capacitor must be selected for the common collector (or an additional resistor used in parallel with the capacitor).

The time delay for the common emitter will be approximately 3 time constants or 3*R*C. The capacitor/resistor values can be worked out from the relay coil current and transistor gain. For example a 120 ohm relay coil will draw 100 mA at 12 volts and assumming a transistor gain of 30, the base current will be 100/30 = 3 mA. The voltage across the resistor will be the supply voltage minus two diode drops or 12-1.4 = 10.6. The resistor value will be the voltage/current = 10.6/0.003 = 3533 or about 3.6K. The capacitor value for a 15 second delay will be 15/3R = 1327 uF. We can use a standard 1000 uF capacitor and increase the resistor proportionally to get 15 seconds.

Here is a series of Touch Switch using only 3 transistors, this touch-based transistor switches can activate a load simply by the user touching a metal plate. It is designed to directly switch a relay to allow it to be used with large loads. As it uses only a few commonly available transistors and a 12V supply, it is ideal for hostile environments where mechanical switches would be damaged. Using a latching relay and two of these circuits, a simple two pad "touch on / touch off" arrangement can be made.

The touch pad can be most easily made by cutting a small square of PCB material and then soldering on a single wire. Alternatively, something like a penny glued to a plastic backing will do the job.

AUDIO TONE CONTROL 2 TRANSISTOR CIRCUIT SCHEMATIC DIAGRAM

Audio tone control circuit based transistors on these provides a maximum cut and boost of around 10dB at 10K and 50Hz.
audio tone control 2 transistorSkema rangkaian audio tone control 2 transistor


The first BC109C transistor is acting as a buffer. It provides the circuit with a high input impedance, around 250k has a voltage gain of slightly less than unity. As the Baxendall tone control circuit is a passive design, all audio frequencies are attenuated. The position of the controls and reactance of the capacitors alters the audio response. The last transistor provides a slight boost of about 3x. The output is designed to feed an amplifier with input impedance of 10k to 250k. Both tone controls should be linear type Potentiometers.


quick Data Transistor BC109C

Low current max. 100 mA
Low voltage max. 45 V
Collector-base voltage open emitter 30 V
Collector-emitter voltage open base - 20 V
Peak collector current - 200 mA
total power dissipation Tamb £ 25 °C - 300 mW
DC current gain (hFE ) IC = 2 mA; VCE = 5 V 200 - 800
transition frequency IC = 10 mA; VCE = 5 V; f = 100 MHz 100 - MHz

SKEMA RANGKAIAN PENENTU B-C-E TRANSISTOR

Basis-Collector-Emitter Transistor

Testing procedure:

    * Connect randomly the pins of the transistor under test to J1, J2 and J3 sockets or clips.
    * Close SW1, SW2 and SW3.
    * Push on P1; if the transistor is in good health the response of the Identifier will be:
    * Two terminals will show both LEDs illuminated, the remaining one will show a single LED illuminated.
    * If the LED illuminated is Red, the pin connected to the related connector will be the Base of a NPN transistor.
    * If the LED illuminated is Green, the pin connected to the related connector will be the Base of a PNP transistor.
    * Open the switch related to the single illuminated LED: the two terminals showing both LEDs illuminated will change their state and a single LED per terminal will be illuminated. The LED which previously indicated the Base pin will turn-off.
    * If the transistor was previously identified as NPN, the pin connected to the now illuminated Green LED will be the Emitter, whereas the pin connected to the Red LED will be the Collector.
    * If the transistor was previously identified as PNP, the pin connected to the now illuminated Red LED will be the Emitter, whereas the pin connected to the Green LED will be the Collector.