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Friday, February 14, 2020



Here is a simple non-contact AC power monitor for home appliances and laboratory equipment that
should remain continuously switched-on. A fuse failure or power breakdown in the equipment going unnoticed may cause irreparable loss. The monitor sounds an alarm on detecting power failure to the
equipment. The circuit is built around CMOS IC CD4011 utilising only a few components. NAND gates N1 and N2 of the IC are wired as an oscillator that drives a piezobuzzer directly. Resistors R2 and R3 and capacitor C2 are the oscillator components. The amplifier comprising transistors T1 and T2 disables the oscillator when mains power is available. In the standby mode, the base of T1 picks up 50Hz mains hum during the positive half cycles of AC and T1 conducts. This provides base current to T2 and it also conducts, pulling the collector to ground potential  As the collectors of T1 and T2 are connected to pin 2 of NAND gate N1 of the oscillator, the oscillator gets disabled when
the transistors conduct. 

Capacitor C1 prevents rise of the collector voltage of T2 again during the negative half cycles. When the power fails, the electrical field around the equipment’s wiring ceases
and T1 and T2 turn off. Capacitor C1 starts charging via R1 and preset VR and when it gets sufficiently charged, the oscillator is
e n a b l e d and the piezobuzzer produces a shrill tone. Resistor R1 protects T2 from short circuit if VR is adjusted to zero resistance. The circuit can be easily assembled on a perforated/breadboard. Use a small plastic case to enclose the circuit and a telescopic antenna as aerial. A 9V battery can be used to power the circuit. Since the circuit draws only a
few microamperes current in the standby mode, the battery will last several months. After assembling the circuit, take the aerial near the mains cable and adjust VR until the alarm stops to indicate the standby mode. The circuit can be placed on the equipment to be monitored close to the mains cable.

Monday, November 18, 2019

Dual Audio Analog Switches

  • “Clickless” Bilateral Audio Switching
  • Guaranteed “Break-Before-Make” Switching
  • Low Distortion: 0.003% typ
  • Low Noise: 1 nV/Hz
  • Superb OFF-Isolation: 120 dB typ
  • Low ON-Resistance: 60 V typ
  • Wide Signal Range: VS = 618 V; 10 V rms
  • Wide Power Supply Range: 620 V max
  • Available in Dice Form

The SSM2402/SSM2412 are dual analog switches designed specifically for high performance audio applications. Distortion and noise are negligible over the full audio operating range of 20 Hz to 20 kHz at signal levels of up to 10 V rms. The SSM2402/ SSM2412 offer a monolithic integrated alternative to expensive and noisy relays or complex discrete JFET circuits. Unlike conventional general-purpose CMOS switches, the SSM2402/SSM2412 provide superb fidelity without audio “clicks” during switching. Conventional TTL or CMOS logic can be used to control the switch state. No external pull-up resistors are needed. A “T” configuration provides superb OFF-isolation and true bilateral operation. The analog inputs and outputs are protected against overload and overvoltage. An important feature is the guaranteed “break-before-make” for all units, even IC-to-IC. In large systems with multiple switching channels, all separate switching units must open before any switch goes into the ON-state. With the SSM2402/ SSM2412, you can be certain that multiple circuits will all break-before-make. The SSM2402/SSM2412 represent a significant step forward in audio switching technology. Distortion and switching noise are significantly reduced in the new SSM2402/SSM2412 bipolar JFET switches relative to CMOS switching technology. Based on a new circuit topology that optimizes audio performance, the SSM2402/SSM2412 make use of a proprietary bipolar JFET process with thin-film resistor network capability. Nitride capacitors, which are very area efficient, are used for the proprietary ramp generator that controls the switch resistance transition. Very wide bandwidth amplifiers control the gate-to-source voltage over the full audio operating range for each switch. The ON-resistance remains constant with changes in signal amplitude and frequency, thus distortion is very low, less than 0.01% max. The SSM2402 is the first analog switch truly optimized for high-performance audio applications. For broadcasting and other switching applications which require a faster switching time, we recommend the SSM2412—a dual analog switch with one-third of the switching time of the SSM2402.

Sunday, November 17, 2019

How to Made Double Voltage

A voltage multiplier in its most basic sense works on the principle that "A CAPACITOR IS A CAPABLE OF STORING CHARGE AND THAT IT HAS THE SAME POTENTIAL AS THE SOURCE WHICH CHARGED IT". Now, the whole idea is that in an AC system you use capacitors in such a way that the net output voltage should be, say double of what you would otherwise get. This circuit will be called a voltage doubler. Now lets have a look at the action that actually happens to double the voltage.


The image you see is a schematic of a voltage doubler, few things to notice about it. The transformer gives output between points A and B. The load is connected between points A * and B *, but also there are two capacitors between those two points and point C is common to both.

Now to begin analyzing imagine a sine wave coming in. The first diode is forward biased and so conducts and in an attempt to do that it charges the first capacitor, now in the second half cycle of the wave the second diode is forward biased and so the second capacitor is charged. Now since the load is between the two capacitors, it is more like two batteries connected in series with each other.

Thus and the voltage in the series adds up, the net voltage across the load is twice the voltage that the transformer can deliver. Voltage multipliers are most commonly used at places where you wish to have high AC voltage when the transformer of the required rating is not available

Monday, December 3, 2018

Electronics TL-Lamp 12 volt DC

By David Bradbury
The circuit shown in Figure below has been designed to drive an 8Wfluorescent lamp from a 12V source, using an inexpensive inverter based on the ZTX652 transistor. The inverter will operate from supplies in the range of 10V to 16.5V, attaining efficiencies up to 78% thus making it suitable for use in on-charge systems such as caravans / mobile homes/ RVs as well as periodically charged systems such as roadside lamps, camping lights or outhouse lights etc. Other features of the inverter are that it oscillates at an inaudible 20kHz and that it includes reverse polarity protection. Circuit Operation The 270W and 22W resistors bias a ZTX652 transistor into conduction, where the positive feedback given to the transistor byW1 drives it into saturation, thus applying the supply voltage across W2. This causes a magnetizing current to build up in W2 until the transformer’s ferrite core saturates. When this happens, the base drive given to the transistor by W1 decays, causing the transistor to rapidly turn off.

Transformer winding using ferite transformer here:

Sunday, November 16, 2014

How to Repair Fan Motor

If you have broken fan motor because of broken winding stator you can fixed it with easily just buy ones the winding stator motor like this. In my country it is about Rp 78.000 ($78).

But you must check the same size and type. And then wiring of the stator motor connect to cables like this:
Wiring normalnya adalah sbb:
White Cable:  is main (center)
Capasitor: 1. Red <==> BLUE cables [of stator cables]
                2.Black  <==>  Oranye cables [of stator cables]
3 other cables for speed control

In this case I fixed fan merk of Miyako with feature: Remote control:
1. On-Off
2. Speed control of 3 condition
3. Timer: 1/2, 1, 2, 4 minutes combination sleep timer
4. Speed model : sepoi and others

complete remote control circit at here

Sunday, August 10, 2014

USB to Serial Converter Home Made without Microcontroller IC - No need programming

USB to Serial converter home made without IC microcontroller or no need programming can realization using special IC for that. It is TF 232 BM. For more explanation will shown in this circuit:

At the PC side you need driver software (winxp and lower) but for win7 up no need driver.

Complete Circuit/Driver/Schematic can download at HERE

Most of today's PCs and notebooks began to leave the serial port and switch to USB. The use of USB is more practical because in addition to its speed higher, this port has a 5 volt voltage source that can be used to provide resources on an electronic system that is connected to it. While today most electronic devices are still using the port RS232 communication with PC media. To bridge these problems  so many products launched USB to RS232 which makes electronic devices is still detected as COM (RS232 port) on the PC or notebook. Old software that was previously still using COM does not need to be changed  again because the device is still considered to communicate with COM (Port RS232) But most of USB products on the market toRS232 still using 12 Volt +/- level on the microcontroller whereas RS232 can only use TTL level 0 / + 5Volt just so needed IC MAX232 again to communicate with this module. 

RS232 Converter production has TTL level 0 / + 5 volts on the RS232nya so it can be connected directly to the microcontroller system without using a MAX232.
Installation HOME MADE USB - Serial Converter:
- Connect the USB cable to a PC's USB port and USB port Home Made this circuit
- Power LED indicator will indicate the presence of active voltage source Module enters the This circuit
- Windows will ask for the driver of the module to be installed

Driver installation step by step:

To testing connection use Hyperterminal

Step Down Power Supply Up to 30A Output

This circuit is so simple for step down power supply with the one IC controller like this

Key Features

    • Fully-encapsulated dual step-down switching power supply
    • Up to 100W output from a 17mm square PCB footprint
    • Dual 15A or single 30A output
    • Up to 95% conversion efficiency
    • 4.5V to 20V input voltage range
    • 0.6V to 6V output voltage range
    • 1.5% output voltage accuracy with differential remote sensing
    • Up to six modules may be paralleled to support 180A output current
    • Output over-voltage, over-current and over-temperature protection
    • Full power operation without heat sinks or fans
    • QFN package with exposed leads permits easy probing and visual solder inspection


The ISL8225M is a fully-encapsulated step-down switching power supply that can deliver up to 100W output power from a small 17mm square PCB footprint. The two 15A outputs may be used independently or combined to deliver a single 30A output. Designing a high-performance board-mounted power supply has never been simpler -- only a few external components are needed to create a very dense and reliable power solution.

Automatic current sharing and phase interleaving allow up to six modules to be paralleled for 180A output capability. 1.5% output voltage accuracy, differential remote voltage sensing and fast transient response create a very high-performance power system. Built-in output over-voltage, over-current and over-temperature protection enhance system reliability.

The ISL8225M is available in a thermally-enhanced QFN package. Excellent efficiency and low thermal resistance permit full power operation without heat sinks or fans. In addition, the QFN package with external leads permits easy probing and visual solder inspection.


    • Computing, networking and telecom infrastructure equipment
    • Industrial and medical equipment
    • General purpose point-of-load (POL) power


If you need high voltage or more headroom, you can move to the ISL8240M dual 20A/single 40A step-down power module, which is pin-to-pin compatible with the ISL8225M, and is well suited for power hungry ASIC, FPGA and microprocessor loads in infrastructure systems. Current sharing and phase interleaving allow up to 6 modules to be paralleled for up to 240A of current. 

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