Rangkaian Kristal Tester

Kristal Tester

In the world of electronics using crystal oscilator almost always in use. In the circuit below is a series to test the crystal. (Not measuring frequensy). With this circuit we could find out whether the crystal is still good or not. Test Clip to attach electrodes on crystal (foot), S1 in the press (On) then LED1 will light up if the crystal is still good. if you mendapa difficulties 2N356U transistors can be used with the type of transistor NTE123AP / PN100 / 2N3904.

Skema rangkaian kristal tester

The mechanism of this crystal tester is very simple. If a good crystal is connected to the test lead, the oscillator will work, and an AC signal will be generated at Q1 emitter. This AC signal will flow through capacitor C3 and trigger the Q2 to light the LED indicator. The diode 1N4148 provide the back path for the AC signal. If the crystal is bad, the oscillator won’t work, and there is only DC voltage level at Q1 emitter. This DC voltage level won’t trigger the Q2 transistor since the capacitor C3 block any DC signal. You can use any high gain high frequency transistor for this crystal tester circuit, in case you can’t find exact transistor series as shown in the schematic diagram.

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Rangkaian Kabel (lan) Tester.

Kabel Tester

Circuit of cable tester with a separate LED Will show open circuits, short circuits, reversals, earth faults, continuity and all with four IC's. The circuit comprises transmitter and receiver, the cable under test linking the two. The transmitter is nothing more than a "LED chaser" the 4011 IC is wired as astable and clocks a 4017 decade counter divider. The 4017 is arranged so that on the 9th pulse,the count is reset. Each LED will light sequentially from LED 1 to LED 8 then back to LED 1 etc. As the 4017 has limited driving capabilities, then each output is buffered by a 4050. This provides sufficient current boost for long cables and the transmitter and receiver LED's. The receiver is simply 8 LED's with a common wire.

Skema rangkaian kabel (lan) tester

Pinning IC 4017

With a good cable and all wires connected then LED 1 will light at both cable ends, followed in sequence by LED 2 ,3, 4 etc to LED 8, the sequence then repeating. If a 4 wire cable is used, it must be connected to use the common. The sequence would be LED 1,2,3,4 repeating with a delay as the 4 unused outputs are stepped through. To check for earth contact faults, the probe labeled "to earth connection" would be physically connected to a local earth. A wire that is earthing will dim or extinguish the LED's at both ends of the cable. An LED not lighting at the receiver, indicates a broken or open circuit.

The LED sequence of course is stepped through, as you know the transmitter "pattern" it is easy to tell the state of the cable by viewing the receiver pattern. The earth condition will only show up if the contact to earth is less than 1000 ohms, a better but more time consuming method for earth faults is to use a meter on the Megaohms range.

Source

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Fuse|Sekring Elektronika.

Rangkaian Fuse Elektronika

Circuit of fuse (sekring) electronic designed to operate on 230V AC with an adjustable trip current. When the current through the load exceeds a level determined by the position of the wiper on the 1k wire-wound pot, this circuit cuts off the load immediately. If S1 is open, the range is approximately 300-650 mA, and 0.8-2A when it is closed.

Skema rangkaian fuse|sekring elektronika

Note:

• This circuit connects directly to 220-230V AC which can be lethal! Please do not attempt to build any of the circuits/projects unless you have the expertise, skill and concentration that will help you avoid an injury.
• D1: 1N4001
• T1: TIC225M
• T2: BTA12-600CW

The key variable in the operation of the fuse is the voltage drop across the power resistor(s) which are connected in series with the load. This voltage drop is directly proportional to the current the load draws. When this current is low, the voltage across the resistors is also small and cannot trigger T1. At the same time the gate of T2 is fed from a little power supply built around a negative voltage regulator. T2 is conducting and the load is on.

If the current through the load then gets too high, so that the voltage created across the resistor(s) can trigger the gate of T1 through the 330R resistor and the pot: T1 starts to conduct, swiftly taking away all the current from the gate of T2. The voltage drop across T1 (MT1-MT2) will then be only 0.7 V and T2 will be firmly off. T1 stays this way all until the momentary (normally closed, "push-to-break") Reset push-button is pressed: this causes the current through T1 to drop below the hold level and forces this triac to turn off. Releasing the Reset button re-enables the current flow to and through the gate of T2, switching it on.

Thanks to www.zen22142.zen.co.uk

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Rangkaian Op-Amp (LM741) Pre-Amp Mic

Op-Amp Pre-Amp Mic

This is the circuit of Op-Amp Microphone Preamplifier using a single power supply, this circuit suitable for dynamic or electret microphones. Nothing too special here. The Schematic is shown using a dynamic microphone, for use with an electret a pair of suitable biasing resistor is required to power the electret microphone.

Skema rangkaian op-amp pre-amp mic

Note:

• use a capacitor with voltage 25volt or more
• so that the sound produced maximal use supplay good voltage, with output of 18 volts max
• If the desired strengthening of the different, you can change the value of R1 or R2

The design is a standard non-inverting design, the input is applied to the non-inverting input of the op-amp, which is pin 3 in most cases. The input impedance is 23.5k, the overall voltage gain is determined by R2 and R1according to the following formula:

Vo = (R2 / R1) + 1

With the values of R2 and R1 on the diagram of the voltage gain (for mid band, 1kHz) is approximately 23x or 27.2dB.

Pinning IC Op-Amp LM741

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Rangkaian Indikator Suhu Air.

Indikator Suhu Air

This is a circuit that serves to indicate various levels of hot water in a tank. SW1 is a normally open press button switch which allows you to view the level of hot water in a hot water tank. When pressed the voltage difference at the junction of the thermistor and preset is compared to the fixed voltage on the op-amps non-inverting input. Depending on the heat of the water in the tank, the thermistors resistance will toggle the op-amp output to swing to almost full voltage supply and light the appropriate LED.

Skema rangkaian indikator suhu air

Note:

• Op-Amp: LM324 or any quad opamp can be used or even four single op-amps.
• R2-R5: 330ohm resistors, but Lower values give brighter LED output.
• NTC1-4: Cold resistance was around 300K, hot resistance 15k. Alternative thermistors may be used with different resistance ranges, but the presets P1 to P4 must also be changed as well.
• R7-10: only required if your thermistors resistance is several ohms at the hottest temperature.
• P1 - P4: Chosen to match the resistance of the thermistor when cold.
• R1 & R6: 100k Resistor

Masking tape was used to stick the bead thermistors to the tank. Wires were soldered and insulated at the thermistors ends. A plastic box was used to house the circuit. Battery life will probably be 4 to 5 years depending on how often you use the push switch, SW1.

Thermistors NTC1-4 should be spread evenly over the height of the tank. I placed NTC1 roughly 4 inches from the top of my tank and the others were spaced evenly across the height of the hot water tank. As hot water rises the lowest sensor indicates the fullest height of hot water and should be about 8 to 10 inches from the bottom of the tank.

With a full tank of hot water adjust P1-4 so that all LED's are lit. As hot water rises, the sensor at the bottom of the tank will be the maximum level of hot water. "Hot" can be translated as 50C to 80C the presets P1-4 allow adjustment of this range.

Source

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Rangkaian Osilator Gelombang Sinus Variabel.

Osilator Gelombang Sinus Variabel (15 to 150kHz)

This is a circuit of sine wave oscillators covering a frequency range of 15 to 150kHz in four switched steps. Two conditions exist for a sinusoidal oscillator. Regenerative or positive feedback, and a closed loop gain of unity. The losses in the wien feedback circuit, are such that the open-loop gain of the amplifier must also exceed 3.

Skema rangkaian osilator sinus variabel

The circuit gain is provided by a FET type op-amp (LF351), but LF351 may be difficult to obtain, for a replacement you can use TL071CN or TL081CN. The Maplin order codes are RA67X and RA70M respectively. The wien network is a parallel combination of resistors and capacitors, in series with a series RC network. Regenerative feedback is applied from the op-amp output, to the serail RC input and continues. Stabilization is required to prevent the otherwise Uncontrolled oscillation from building up and becoming unstable.

There are two common methods of stabilizing a wien oscillator type. A thermistor with a NTC in the series leg of the feedback loop or an incandescent lamp (with a positive temperature coefficient) in the shunt leg of the feedback loop. The bulb used here is a 6V 60mA type Maplin code BT99H. A 12 Volt bulb rated 60mA or 40mA will also work. The feedback arrangement works as follows. As a bulb filament heats up its resistance increases. This will decrease the overall gain of the amplifier, as the output signal is fed back to the input.Similarly, if the output of the signal amplitude decreased Appearing at the bulb would be less, its filament resistance would drop and the gain would be increased. Therefore a stable output amplitude is produced. The 1k preset is adjusted for minimum distortion. Note that split supplies are used and a ganged 10k Potentiometer controls with a 10:1 frequency range.

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