Showing posts with label transistor. Show all posts
Showing posts with label transistor. Show all posts
Friday, November 15, 2013
Transistor Checker with 555 Timer 4027IC
This regular circuit has helped me prohibited on many occasions. It is able to check transistors, inside the circuit, down to 40 ohms across the radio dish-foot otherwise base-emitter junctions. It can in addition check the output power transistors on amplifier circuits. Circuit company is because follows. The 555 timer ( IC1 ) is usual up as a 12hz multi vibrator. The output on pin 3 drives the 4027 flip-dud ( IC2). 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 LEDs are arranged so to facilitate what time the polarity across the circuit is lone way single one LED force light and what time the polarity reverses the other LED will light, therefore while rebuff transistor is connected to the tester the LEDs will alternately flicker. The IC2 outputs are too connected to resistors R4 and R5 with the junction of these two resistors connected to the immoral of the transistor being tested. With a proficient transistor connected to the tester, the transistor yearn for circle on and crop a passing across the LED duo. If a good NPN transistor is connected next LED1 will burst by itself and if a good PNP transistor is connected then LED2 will flash by itself. If the transistor is initiate both LEDs force flash and if the transistor is shorted at that moment neither LED will flash.
Monday, November 11, 2013
Transistor Water Sensor Alarm
This water sensor alarm circuit diagram is designed using common electronic components. Thewater sensor alarm circuit may operate an active buzzer, to make a sound when is reached a certain level of water.
Transistor Water Sensor Alarm Circuit Diagram
Because water sensor and control circuit for buzzer are located on the same printed circuit board, indicator, together with 9 V battery and buzzer can be mounted in a compact case.
When water reaches the sensor, the base of T1 is connected to the positive supply terminal. Therefore, T1 and T2 are open, so that buzzer BZ1, will be activated. Sensitivity reduction of the circuit can be done by increasing the value of R2.
Transistor Water Sensor Alarm Circuit Diagram
When water reaches the sensor, the base of T1 is connected to the positive supply terminal. Therefore, T1 and T2 are open, so that buzzer BZ1, will be activated. Sensitivity reduction of the circuit can be done by increasing the value of R2.
Thursday, November 7, 2013
Michas AVR Transistor tester
Everyone knows the problem: you have a transistor, but you can not read the signature. Or you can not find the datasheet. You have a diode or you have a capacitor, but you can not read ... Here is the solution smarty.
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| Michas_AVR-Transistortester |
Features:
* Automatic detection of NPN and PNP transistors, N-and P-channel MOSFET, the diode (including the double diode), thyristor, triac and resistor.
* Automatic pin detection and reporting of test components
* Detect and display protection diode and the MOSFET transistor
* Determination of the amplification factor and the forward base-emitter voltage of transistor
* Measurement of threshold voltage and gate capacitance of MOSFET
* Show the value of the text-LCD (2 × 16)
* One-button operation, automatic shut-off
* Power consumption in off mode: <20 nA
This tester also supports measuring the diode, R / C testing, and many other components identified.
Saturday, November 2, 2013
Single Transistor Relay Toggle
The circuit below requires a double pole, double throw relay in conjunction with a single transistor to allow toggling the relay with a momentary push button. One set of relay contacts is used to control the load, while the other is used to provide feedback to keep the relay activated or deactivated. Several push buttons can be wired in parallel to allow toggling the relay from different locations.
In the deactivated state, the relay contacts are arranged so the 1000 uF capacitor will charge to about 2.7 volts. When the switch is closed, the capacitor voltage is applied to the transistor base through a 560 resistor causing the transistor to turn on and activate the relay. In the activated state, the relay contacts are arranged so the 3.3K resistor and 560 ohm resistor provide a continous current to the transistor base maintaining the activated state. While in the activated state, the capacitor is allowed to discharge to zero through the 1K resistor. When the switch is again closed, the capacitor will cause the transistor base to move toward ground deactivating the relay.
Single Transistor Relay Toggle Circuit Diagram
The circuit has three distinct advantages, it requires only a few parts, always comes up with the relay deactivated, and doesnt need any switch debouncing. However since the capacitor will begin charging as soon as the button is depressed, the button cannot remain depressed too long to avoid re-engaging the relay. This problem can be minimized with an additional resistor connected from the transistor base to ground so that the base voltage is close to 0.7 volts with the button depressed and the transistor is biased in the linear region. With the button held down, the relay coil voltage should be somewhere between the pull in and drop out voltages so that the relay will maintain the last toggled state.
This worked out to about 820 ohms for the circuit I built using a 12 volt, 120 ohm relay coil and 2N3053 transistor. Temperature changes will effect the situation but the operation is still greatly improved. I heated the transistor with a hair dryer and found that the relay will re-engage with the button held down for approximately 1 second, but this is not much of a problem under normal operation.
In the deactivated state, the relay contacts are arranged so the 1000 uF capacitor will charge to about 2.7 volts. When the switch is closed, the capacitor voltage is applied to the transistor base through a 560 resistor causing the transistor to turn on and activate the relay. In the activated state, the relay contacts are arranged so the 3.3K resistor and 560 ohm resistor provide a continous current to the transistor base maintaining the activated state. While in the activated state, the capacitor is allowed to discharge to zero through the 1K resistor. When the switch is again closed, the capacitor will cause the transistor base to move toward ground deactivating the relay.
Single Transistor Relay Toggle Circuit Diagram
The circuit has three distinct advantages, it requires only a few parts, always comes up with the relay deactivated, and doesnt need any switch debouncing. However since the capacitor will begin charging as soon as the button is depressed, the button cannot remain depressed too long to avoid re-engaging the relay. This problem can be minimized with an additional resistor connected from the transistor base to ground so that the base voltage is close to 0.7 volts with the button depressed and the transistor is biased in the linear region. With the button held down, the relay coil voltage should be somewhere between the pull in and drop out voltages so that the relay will maintain the last toggled state.
This worked out to about 820 ohms for the circuit I built using a 12 volt, 120 ohm relay coil and 2N3053 transistor. Temperature changes will effect the situation but the operation is still greatly improved. I heated the transistor with a hair dryer and found that the relay will re-engage with the button held down for approximately 1 second, but this is not much of a problem under normal operation.
Saturday, October 12, 2013
4 Transistor 500mW FM Transmitter Circuit Diagram
4 Transistor 500mW FM Transmitter Circuit DiagramAs shown, the audio ascribe is a microphone, which uses 2 x 2N3904 as the microphone audio preamplifier. The audio/mic ascribe akin is adjustable by agency of a 5k preset / potentiometer.
The ambit uses a Colpitts oscillator for abundance generation, which is chargeless active and operates at the axiological abundance i.e. no circuitous abundance multiplication or control. The abundance affability basic of the ambit consists of 2 5pF (picoFarad) capacitors and a distinct 10uH (micro-Henry) inductor. These apparatus can be adapted if a change in abundance is appropriate - conceivably alike replaced with capricious capacitors (if youre up to the challenge).
An achievement RF amplifier takes the abundance produced by the Colpitts oscillator and amplifier to about about the 500mW (0.5 Watt) ambit - so this is the almost achievement ability of this FM transmitter. You are brash that back this transmitter operates at the axiological frequency, and because there is no achievement filter, there is acceptable to be some abundance alluvion and harmonics/spurious emissions.
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